JPH07267105A - Lock detection device for electric power steering system - Google Patents

Abstract

(57) [Abstract] [Object] An object of the present invention is to perform a lock determination during normal control of an electric power steering apparatus, without requiring a special actuator operation for the lock determination, and to detect an abnormality. A quick warning can be given, the lock judgment can be loosened, the structure can be simplified both hardware and software, the configuration can be simplified, and the cost can be reduced. . Therefore, according to the present invention, the lock detection of the electric power steering device that assists the operation force of the steering wheel by transmitting the driving force of the electric motor to the output shaft via the clutch mechanism based on the detection signal of the steering sensor. In the device, the torque value applied between the input shaft and the output shaft is calculated from the displacement amount due to the relative rotation between the input shaft and the output shaft detected by the steering sensor, and this torque value releases the clutch mechanism and drives the electric motor. A control means is provided to process the lock determination of the drive system of the electric motor when the torque is within the predetermined lock determination torque range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lock detecting device for an electric power steering device, and more particularly, it can perform a lock judgment during normal control of the electric power steering device.
No special actuator operation is required to determine the lock of the electric motor drive system, a warning can be promptly issued when an abnormality is detected, and manual steering is possible even when the electric motor drive system is locked. By providing the 3-way type clutch mechanism, the lock determination can be loosened, the structure can be simplified in terms of hardware and software, the configuration can be simplified, and the cost can be reduced. The present invention relates to a lock detection device for an electric power steering device.

[0002]

2. Description of the Related Art Some vehicles are provided with a power steering device for assisting the operating force of the steering wheel in order to assist the operating force to reduce the burden on the driver. The power steering device utilizes hydraulic power, compressed air, electricity, etc. as a power source, and is provided with appropriate control means corresponding to those power sources.

An example of the power steering device is an electric power steering device using an electric motor. The electric power steering device can freely adjust the assist for the operating force required by the driver.

A lock detecting device for such an electric power steering device is disclosed in Japanese Patent Laid-Open No. 63-215461. What is disclosed in this publication is that the assist by the electric motor is interrupted by an electromagnetic clutch, and the characteristic value is measured by driving the electric motor before connecting the electromagnetic clutch, and the measured value and the set value are compared. Then, the lock determination of the drive system is performed, and the electromagnetic clutch is engaged or fail-safe operation is performed depending on the result.

[0005]

By the way, in the conventional electric power steering apparatus, an input shaft connected to a steering wheel of a vehicle and an output shaft connected to a steering gear are relatively rotatable via an elastic body. If the displacement amount due to the relative rotation between the input shaft and the output shaft is less than the set value, the shaft is disengaged from the output shaft, and the displacement amount due to the relative rotation between the input shaft and the output shaft reaches the set value. A clutch mechanism that engages with the output shaft when exceeded is provided, and an electric motor that interrupts the transmission of driving force to the output shaft by this clutch mechanism is provided. By providing a steering sensor for detecting, and transmitting the driving force of the electric motor to the output shaft via the clutch mechanism based on the detection signal of the steering sensor, the steering wheel There are things to assist the operation of the force.

In this electric power steering system, the driving force of the electric motor is applied to assist the steering wheel operating force after the displacement of the input shaft and the output shaft becomes large with respect to the engagement of the clutch mechanism. . Conventionally, FIG.
As shown in FIG. 4, the amount of displacement of the clutch mechanism engaged / disengaged is detected by the steering sensor, and the torque value T applied between the input shaft and the output shaft is calculated from this displacement amount.

In the electric power steering apparatus, the assist start torque value T _SA (T ', which is larger than the clutch engagement / disengagement torque value T ₁ (T' ₁ ) calculated from the displacement amount when the clutch mechanism is engaged / disengaged. _SA ) is set and the torque value T calculated from the amount of displacement detected by the steering sensor exceeds the assist start torque value T _SA (T ′ _SA ), the drive of the electric motor is started to start the assist.

Further, the electric power steering apparatus has an assist stop torque value T _SP (T ′) which is larger than the clutch engagement / disengagement torque value T ₁ (T ′ ₁ ) and the assist start torque value T _SA (T ′ _SA ). _SP ) is set, and when the torque value T calculated from the displacement amount detected by the steering sensor becomes equal to or less than the assist stop torque value T _SP (T ′ _SP ), the driving of the electric motor is stopped and the assist is stopped.

This is to prevent the inconvenience that when the clutch mechanism is engaged after the driving of the electric motor is started, the steering wheel is abruptly assisted to generate an abnormal noise and an uncomfortable feeling in operation. This is because. Therefore, conventionally, the driving force of the electric motor is applied after the displacement amount (torque value) between the input shaft and the output shaft becomes sufficiently large after the clutch mechanism is engaged.

However, when the displacement amount due to the relative rotation between the input shaft and the output shaft is less than a set value, the displacement amount due to the relative rotation between the input shaft and the output shaft is released with respect to the output shaft. The clutch mechanism that is engaged with the output shaft when the torque exceeds the limit is a so-called three-way type clutch mechanism, and manual steering is possible even when the drive system of the electric motor is in a locked state.

Therefore, in the lock detecting device of the electric power steering device provided with a so-called three-way type clutch mechanism, the drive system of the electric motor is actuated by an actuator in a control different from the normal control to perform the lock determination. Therefore, there is a disadvantage that a special actuator operation is required for the lock determination of the drive system of the electric motor, and a lock determination cannot be performed during the control of the electric power steering device.

On the other hand, in the conventional lock detecting device for a general electric power steering device, the drive system of the electric motor is locked because the electric motor is provided with an electromagnetic clutch or the like to interrupt the transmission of the driving force to the output shaft. In this state, manual steering becomes impossible, and therefore it is necessary to always perform lock determination during normal control. For this reason, conventionally, it has been necessary to strictly perform the lock determination, and as a result, the structure becomes complicated both in terms of hardware and software, resulting in an increase in cost.

[0013]

SUMMARY OF THE INVENTION In order to eliminate such inconvenience, the present invention relates to relative rotation between an input shaft connected to a steering wheel of a vehicle and an output shaft connected to a steering gear via an elastic body. If possible, the input shaft and the output shaft are disengaged from the output shaft and the relative rotation between the input shaft and the output shaft when the displacement amount due to the relative rotation between the input shaft and the output shaft is less than a set value. Is provided with a clutch mechanism that is engaged with the output shaft when the displacement amount exceeds a set value, and an electric motor that interrupts the transmission of the driving force to the output shaft by the clutch mechanism is provided with the input shaft and the output shaft. A steering sensor that detects the amount of displacement and the direction of displacement due to relative rotation with respect to the In a lock detecting device for an electric power steering device that assists the operating force of the steering wheel by transmitting to the input shaft and the output shaft, the lock amount detecting device detects the steering shaft from the relative displacement between the input shaft and the output shaft. A torque value applied to the output shaft is calculated, and when the torque value is within a predetermined lock determination torque range in which the clutch mechanism is disengaged and the electric motor is being driven, the drive system of the electric motor is locked. It is characterized in that a control means for processing to make the judgment is provided.

[0014]

According to the structure of the present invention, in the lock detecting device of the electric power steering system, the control means controls the input shaft and the output shaft from the displacement amount due to the relative rotation between the input shaft and the output shaft detected by the steering sensor. The torque value applied during the period is calculated, and if this torque value is within the predetermined torque range for lock determination in which the clutch mechanism is disengaged and the electric motor is being driven, processing is performed to perform lock determination of the drive system of the electric motor. is doing. With this, when the steering wheel is operated, the lock detection device causes the torque value calculated from the displacement amount detected by the steering sensor to fall within a predetermined lock determination torque range in which the clutch mechanism is disengaged and the electric motor is driven. Thus, the lock determination is performed every time the steering wheel is operated.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 13 show an embodiment of the present invention. In FIG. 5, 2 is a vehicle, 4 is a front wheel, and 6 is a rear wheel. The vehicle 2 travels by driving the front wheels 4 and / or the rear wheels 6 by an internal combustion engine or an electric motor, which is a drive system installed therein. The front wheels 4, which are steered wheels, are steered by a steering wheel 8.

The steering wheel 8 is provided so as to communicate with the steering gear 12 by the steering column 10. The steering column 10 includes a steering shaft 14 connected to the steering wheel 8 and a joint shaft 16 connected to the steering gear 12. The steering gear 12 converts the rotational movement of the joint shaft 16 into a linear movement to reciprocate the tie rod 18, and steers the front wheel 4 which is a steered wheel via a knuckle arm (not shown).

The vehicle 2 is equipped with an electric power steering device 20. Electric power steering device 2
0 is an input shaft 22 connected to the steering wheel 8 via a steering shaft 14 as shown in FIGS. 9 to 13.
And an output shaft 24 connected to the steering gear 12 via a joint shaft 16.

The input shaft 22 and the output shaft 24 are surrounded by an upper housing 26 and a lower housing 28, as shown in FIG. The output shaft 24 is supported by a lower housing 28 by a bearing 30. The input shaft 22 is
The small diameter portion 32 formed on the front end side is relatively rotatably fitted into a fitting hole 36 formed on the large diameter portion 34 on the rear end side of the output shaft 24. The input shaft 22 and the output shaft 24 have an elastic body 40 such as a torsion bar installed in the input side insertion hole 36 and the output side insertion hole 38 formed in the axial direction, and each side end of the elastic body 40 is fixed to the input side. The pins 42 and the output side fixing pin 44 are fixed to each other, and are rotatably supported relative to each other.

The small diameter portion 32 of the input shaft 22 is shown in FIG.
As shown in FIG. 3, one end side of the connecting pin 46 is fixedly installed.
The other end of the connecting pin 46 is inserted into a connecting hole 47 formed in the large-diameter portion 34 of the output shaft 24, and is projected outward from the fitting hole 36 side. The connecting hole 47 is formed larger than the diameter of the connecting pin 46 so as to allow a predetermined rotational displacement of the connecting pin 46 due to relative rotation of the input shaft 22 and the output shaft 24.

A clutch mechanism 48 is provided on the output shaft 24. The clutch mechanism 48 of this embodiment has three
This is a way type clutch mechanism, and as shown in FIGS. 12 and 13, the large diameter portion 34 provided on the output shaft 24 and the connecting pin 46 provided on the input shaft 22, the inner cage 50, and the outer cage 52. And a worm wheel 54, rolling elements 56, and springs 58. The clutch mechanism 48 has an inner cage 50 fitted to the large diameter portion 34 of the output shaft 24, an outer cage 52 fitted to the inner cage 50, and an outer cage 52.
A worm wheel 54 is fitted on the.

The inner cage 50 has the output side fixing pin 4
It is fixed by 4. An insertion hole 60 is formed in the inner cage 50. The connecting pin 46 is rotatably inserted through the insertion hole 60. The other end of the connecting pin 46, which is inserted through the insertion hole 60 of the inner holder 50, is fixed to the outer holder 52. Outer cage 5
2 and the worm wheel 54 are supported by the inner cage 50 by a support tool 62.

In the inner cage 50 and the outer cage 52, the rolling elements 56 are arranged in the inner retaining holes 64 and the outer retaining holes 66, and the rolling elements 56 are elastically biased by the springs 58. The rolling element 56 is formed in a substantially gourd shape, and its length in the longitudinal direction is slightly shorter than the length between the large diameter portion 34 and the worm wheel 54.

In the clutch mechanism 48, when the displacement amount due to the relative rotation of the input shaft 22 and the output shaft 24 is less than or equal to a set value,
As shown in FIG. 12, the large diameter portion 34 and the worm wheel 5
The rolling elements 56 are disposed between the four rollers in a state of being substantially parallel to the diametrical direction. As a result, in the clutch mechanism 48, the rolling elements 56 are not engaged with the large diameter portion 34 and the worm wheel 54 and are in the disengaged state.

In the clutch mechanism 48, when the amount of displacement due to the relative rotation of the input shaft 22 and the output shaft 24 exceeds a set value, the rolling elements 56 are pushed by the springs 58 and the large diameter portion 34 and the worm, as shown in FIG. The wheels 54 are arranged so as to be inclined with respect to the diametrical direction. As a result, in the clutch mechanism 48, the rolling elements 56 are engaged with the large diameter portion 34 and the worm wheel 54, and the clutch mechanism 48 is brought into an engaged state.

As described above, the clutch mechanism 48 is disengaged from the output shaft 24 when the displacement amount due to the relative rotation between the input shaft 22 and the output shaft 24 is less than the set value, and the input shaft 22 and the output shaft 24 are disengaged. When the amount of displacement due to relative rotation with respect to 24 exceeds a set value, the output shaft 24 is engaged.

The clutch mechanism 48 connects and disconnects the transmission of the driving force of the electric motor 68 to the output shaft 24. The electric motor 68 is
As shown in FIG. 10, a motor shaft 70 is supported by a bearing 72 on the upper housing 26. The motor shaft 72 has
Worm gear 74 meshing with the worm wheel 54
Is provided. The driving force of the electric motor 68 is decelerated by the worm wheel 54 and the worm gear 74 that form a reduction mechanism, and is transmitted to the output shaft 24 via the clutch mechanism 48 to assist the operating force of the steering wheel 8.

The electric power steering device 20 is
A steering sensor 76 is provided. As shown in FIG. 11, the steering sensor 76 includes a sensor main body 78, a sensor shaft portion 80 protruding from the sensor main body 78, a plate member 82 fixed at one end side to the sensor shaft portion 80, and the plate member. A sensing portion 84 held on the other end side of 82,
Is provided.

As shown in FIG. 9, the steering sensor 76 is provided with a first slider 86 which is fitted onto the input shaft 22 so as to be axially movable, and a circumferential groove 88 formed in the circumferential direction of the first slider 86. The sensing portion 84 is slidably engaged with the. The second slider 90 is fixed to the first slider 86 by a first C ring 92.

The second slider 90 has an axial guide groove 94.
And a guide shaft 96 is slidably engaged with the guide groove 94. The guide shaft 96 is fixed to a projecting edge portion 98 provided on the large diameter portion 34 of the output shaft 24. The second slider 90 has a ball hole 100 and accommodates a ball 102. The ball 102 is movably engaged with a sensing groove 104 provided on the input shaft 22. The sensing groove 104 is formed in a substantially spiral shape inclined with respect to the axial direction of the input shaft 22.

A cover 106 is attached to the second slider 90 so as to cover the guide shaft 96 and the ball 100. The cover 106 is fixed to the second slider 90 together with the retainer 110 by the second C ring 108. A sensing spring 112 is provided between the retainer 110 and the worm wheel 54.

As shown in FIG. 6, in the steering sensor 76, when the steering wheel 8 is not operated, the input shaft 22 and the output shaft 24 are not twisted and no displacement occurs. Therefore, the steering sensor 76 detects that the ball 10
Since 2 does not move from the neutral position along the sensing groove 104, the first and second sliders 86 and 90 also do not move in the axial direction of the input shaft 22. Therefore, the sensor body 7
8 detects the displacement amount of the input shaft 22 and the output shaft 24 as zero.

As shown in FIGS. 7 and 8, in the steering sensor 76, when the input shaft 22 and the output shaft 24 are twisted and displaced by the operation of the steering wheel 8, the ball 102 moves from the neutral position along the sensing groove 104. By moving the ball 102, the second
The slider 90 is moved in the axial direction of the input shaft 22, and the first slider 86 is also moved in the axial direction of the input shaft 22. The movement of the first slider 86 in the axial direction moves the sensing portion 84 engaged with the circumferential groove 88 in the axial direction, and rotates the sensor shaft portion 80 via the plate member 82. The sensor body 78 detects the rotation amount and the rotation direction of the sensor shaft portion 80 as the displacement amount and the displacement direction between the input shaft 22 and the output shaft 24.

The detection signal of the steering sensor 76 is input to the control unit 114. As shown in FIG. 4, the electric motor 68 and the steering sensor 76 are connected to the control unit 114. The control unit 114 includes an ignition coil 116 for detecting an engine speed of an internal combustion engine (not shown) which is a drive system mounted on the vehicle 2.
And a vehicle speed sensor 118 including a rotor 118a and a reed switch 118b provided in a speedometer section for detecting a vehicle speed, and a generator 120 for detecting a generated voltage.
And the battery 12 via the ignition switch 122.
4 and are connected. Reference numeral 126 is a fuse.

The control unit 114 controls the steering wheel 8
Is operated, the assist amount and the assist direction are determined based on the displacement amount and the displacement direction of the input shaft 22 and the output shaft 24 detected by the steering sensor 76, and the input shaft 22
The driving force of the electric motor 68 is transmitted to the output shaft 24 via the clutch mechanism 48 engaged when the displacement amount between the output shaft 24 and the output shaft 24 exceeds a set value, and the electric motor 68 is assisted to assist the operating force of the steering wheel 8. Control the driving force of.

The electric power steering device 20
May occur in a drive system of the electric motor 68 or the like, and the worm wheel 54 may not operate, for example, a so-called locked state. In this case, the input pin 22 directly rotates the output shaft 24 by bringing the connecting pin 46 into contact with the inner wall of the connection hole 47 formed in the large diameter portion 34 of the output shaft 24. The direct rotation of the output shaft 24 by the input shaft 22 causes the rolling element 54 of the clutch mechanism 48 to rotate.
Is released from the large diameter portion 34 of the output shaft 24 and the worm wheel 54. As a result, the electric power steering device 20 can be manually operated even when the drive system is locked.

This electric power steering device 20 is
A lock detector 128 is provided. Lock detection device 1
28, the control unit 114 calculates a torque value T applied between the input shaft 22 and the output shaft 24 from the displacement amount due to the relative rotation between the input shaft 22 and the output shaft 24 detected by the steering sensor 76. The torque value T (T ′) is a predetermined lock determination torque range T in which the clutch mechanism 48 is disengaged and the electric motor 68 is driven.
If it is within _W (T ' _W ), it is processed to perform the lock determination of the drive system of the electric motor 68.

In the first embodiment, the assist characteristic of the electric motor 68 is set as shown in FIG. The assist characteristic of the electric motor 68 is the assist start torque value T _SA (T ′ _SA ).
Is smaller than the clutch engagement / disengagement torque value T ₁ (T ′ ₁ ) when the clutch mechanism 48 is engaged / disengaged, and the assist stop torque value T _SP (T ′ _SP ) is the clutch engagement / disengagement torque value. The characteristic is set to have a hysteresis larger than T ₁ (T ′ ₁ ).

The control unit 114 controls the assist start torque value T
_SA (T ' _SA ) to clutch disengagement torque value T ₁ (T' ₁ )
To the lock determination torque range T
It is set to _W (T ' _W ). The control unit 114
The torque value T (T ') calculated from the amount of displacement input from the steering sensor 76 is the torque range for lock determination _TW.
If it is within (T ' _W ), the process is performed so as to perform the lock determination of the drive system of the electric motor 68.

Next, the operation of this embodiment will be described.

The electric power steering device 20 includes an input shaft 22 detected by a steering sensor 76 when the steering wheel 8 is operated by the control unit 114.
The assist amount and the assist direction are determined based on the displacement amount and the displacement direction between the input shaft 22 and the output shaft 24.
When the amount of displacement from the output shaft 2 exceeds the set value, the driving force of the electric motor 68 is applied via the clutch mechanism 48 engaged with the output shaft 2
4 to control the driving force of the electric motor 68 to assist the operating force of the steering wheel 8.

The assist amount and the assist direction are not limited to the detection signal of the steering sensor 76, the detection signal of the vehicle speed sensor 118, and the ignition coil 1.
It is determined in consideration of the engine speed based on the ignition signal from 16.

The lock detecting device 128 of the electric power steering device 20 is processed by the control unit 114 so as to perform the lock determination of the drive system of the electric motor 68 as shown in FIG. The control unit 114 controls the driving force of the electric motor 68 to assist the operating force of the steering wheel 8 in a normal control main routine (step 200).
When the start is started, from the displacement amount by the relative rotation of the input shaft 22 and the output shaft 24 detected by the steering sensor 76,
Torque value T applied between the input shaft 22 and the output shaft 24
Calculate (T ').

This torque value T (T ') is judged whether or not it is within a predetermined lock judgment torque range T _W (T' _W ) in which the clutch mechanism 48 is disengaged and the electric motor 68 is driven ( Step 202) is performed. The lock determination torque range T _W (T ′ _W ) is set between the assist start torque value T _SA (T ′ _SA ) and the clutch engagement / disengagement torque value T ₁ (T ′ ₁ ) as shown in FIG. I am doing it.

In the electric power steering device 20, the clutch mechanism 48 is disengaged and the electric motor 68 is operated when the torque value T is within the lock judgment torque range T _W (T ' _W ).
Is being driven. At this time, since the clutch mechanism 48 is disengaged and the electric motor 68 is driven, the worm wheel 54 that constitutes the drive system of the electric motor 68 and the like is
It is being rotated.

If the torque value T (T ') is within the lock determination torque range T _W (T' _W ) (step 20)
2: YES) processes the lock determination (step 204)
To do. The torque value T (T ') is the torque range T for lock determination.
When it is within _W (T ' _W ), the clutch mechanism 48 is disengaged and the electric motor 68 is driven, so that the worm wheel 54 is rotated as described above.

[0046] Therefore, the lock detector 128, the processing of the lock determination in (step 204), before the clutch mechanism 48 is engaged _{(T SA ~T 1: T '} SA ~T' 1)
The rotation detecting means (not shown) detects the rotation of the worm wheel 54, and if the worm wheel 54 is rotating, a normal lock determination is processed. If the worm wheel 54 is not rotating, the abnormal lock is detected. Process the decision. In the lock determination process (step 204), it is determined whether the lock is normal (step 206).

Lock determination is normal (step 206: YE
In the case of S), a normal control process (step 208) for controlling the driving force of the electric motor 68 to assist the operating force of the steering wheel 8 by the electric power steering device 20 is performed, and the process returns to the main routine (step 200). (Step 210).

Abnormal lock determination (step 206: N
In the case of O), an abnormal lamp (not shown) of the electric power steering device 20 is turned on to give a warning to the driver, and the process returns to the main routine (step 200) (step 210).

Further, when it is judged whether or not the torque value T (T ') is within a predetermined lock judgment torque range T _W (T' _W ) (step 202), the torque value T
When (T ′) is outside the lock determination torque range T _W (T ′ _W ) (step 202: NO), the driving force of the electric motor 68 is used by the electric power steering device 20 to assist the operating force of the steering wheel 8. A normal control process (step 208) for controlling the control is performed, and the process returns to the main routine (step 200) (step 210).

As described above, the lock detecting device 128 of the electric power steering device 20 is controlled by the control unit 114 so that the input shaft 22 is detected based on the displacement amount of the relative rotation between the input shaft 22 and the output shaft 24 detected by the steering sensor 76. A torque value T (T ') applied to the output shaft 24 is calculated, and this torque value T (T') is a predetermined lock determination torque range T in which the clutch mechanism 48 is disengaged and the electric motor 68 is driven. Electric motor 68 if in _W (T ' _W )
Processing is performed to determine whether the drive system is locked.

As a result, the lock detecting device 128
When the steering wheel 8 is operated, the torque value T (T ′) calculated from the displacement amount detected by the steering sensor 76 has a predetermined lock determination torque range in which the clutch mechanism 48 is disengaged and the electric motor 68 is driven. T _W
By entering (T ′ _W ), the lock determination is performed every time the steering wheel 8 is operated, at the start of driving the electric motor 68 before the clutch mechanism 48 is engaged.

Therefore, the lock detecting device 128 is
The lock determination can be performed during normal control, and no special actuator operation is required for the lock determination of the drive system of the electric motor 68. In addition, the electric power steering device 20 can quickly give a warning when an abnormality is detected by performing the lock determination during the normal control.

Moreover, the lock detecting device 128 is a so-called three-way type clutch mechanism 48 capable of being manually steered even when the drive system of the electric motor 68 is locked.
Since the lock determination can be made gentler by providing the abnormal lamp that is turned on when the lock determination is abnormal, a short time at the start of driving the electric motor 68 (assist start torque value T _{It is possible} to perform a lock determination between _SA (T ' _SA ) and the clutch engagement / disengagement torque value T ₁ (T' ₁ )), and this determination may be repeated to make a comprehensive determination, both in terms of hardware and software. The structure can be simplified, the configuration can be simplified, and the cost can be reduced.

The above-mentioned lock determination processing (step 2
In 04), the worm wheel 5 before the clutch mechanism 48 is engaged (T _{SA to} T ₁ : T ′ _{SA to} T ′ ₁ ).
Although the rotation determination unit detects the rotation of No. 4 to process the lock determination, the current determination unit (not shown) may detect the current value of the electric motor 68 to process the lock determination.

That is, the electric power steering device 20
Indicates that the torque value T (T ′) is the torque range for lock determination T _W
When in (T ' _W ), the clutch mechanism 48 is disengaged and the electric motor 68 is being driven. At this time, since the electric motor 68 is being driven, a current is flowing.

[0056] Therefore, the in the process of lock determination (step 204), before the clutch mechanism 48 is engaged _{(T SA ~T 1: T '} SA ~T' 1) current detecting a current value of the electric motor 68 of the When the current value of the electric motor 68 is less than or equal to the set value, the normal lock determination is processed, and the electric motor 6 is detected.
If the current value of 8 exceeds the set value, the abnormal lock determination can be processed.

Further, in the lock detecting device 128, as described above, even if the drive system of the electric motor 68 is in the locked state,
By providing the so-called 3-way type clutch mechanism 48 capable of being manually steered, the lock determination can be loosened.

Therefore, in the above embodiment, the control unit 1
The control unit 14 performs processing to perform lock determination of the drive system of the electric motor 68 each time the steering wheel 8 is operated, but the lock determination of the drive system of the electric motor 68 is performed for a predetermined time t.
It can also be processed to be carried out every time. In this way, by performing the lock determination of the drive system of the electric motor 68 at every predetermined time t, the number of lock determination processes can be reduced with respect to the number of times the steering wheel 8 is operated, and the electrical / mechanical processing can be performed. Such a non-operating state can be brought out, which is advantageous in durability and cost.

Further, the lock determination of the drive system of the electric motor 68 is not performed every time the steering wheel 8 is operated, but is thinned out so that the number of times of the operation is reduced with respect to the number of times the steering wheel 8 is operated. You can also do it. As a result, similarly to the case where the lock determination of the drive system of the electric motor 68 is performed every predetermined time t, the number of times of the lock determination processing can be reduced, and the electrical / mechanical non-operation state is revealed. As a result, it can be made advantageous in terms of durability and cost.

FIG. 3 shows a second embodiment of the present invention. Electric motor 6 of lock detecting device 128 of the second embodiment
The assist characteristic of No. 8 is the assist start torque value T _SA (T ′
_SA ) is larger than the clutch engagement / disengagement torque value T ₁ (T ′ ₁ ) when the clutch mechanism 48 is engaged / disengaged, and the assist stop torque value T _SP (T ′ _SP ) is the clutch engagement / disengagement value. The characteristic is set to have a hysteresis that is smaller than the torque value T ₁ (T ′ ₁ ).

The control unit 114 controls the assist stop torque value T
_The clutch engagement / disengagement torque value T ₁ (T ′ ₁ ) from _SP (T ′ _SP ).
To the lock determination torque range T
It is set to _W (T ' _W ). The control unit 114
When the torque value T (T ′) calculated from the displacement amount input from the steering sensor 76 is within the lock determination torque range T _W (T ′ _W ), lock determination of the drive system of the electric motor 68 is performed. Process accordingly.

Next, the operation will be described. The second embodiment will be described with reference to the flow chart of FIG. 1 as in the first embodiment.

The electric power steering device 20 is operated by the control unit 114 when the steering 8 is operated.
The assist amount and the assist direction are determined based on the detection signal of the steering sensor 76, and the driving force of the electric motor 68 is transmitted to the output shaft 24 via the clutch mechanism 48 engaged when the displacement amount exceeds the set value. The driving force of the electric motor 68 is controlled to assist the operating force of the steering wheel 8.

The lock detecting device 128 of the electric power steering device 20 is a main part of a normal control for controlling the driving force of the electric motor 68 by the control unit 114 so as to assist the operating force of the steering wheel 8 as shown in FIG. When the routine (step 200) is started, the torque value T is calculated from the displacement detected by the steering sensor 76.
Calculate (T ').

This torque value T (T ') is judged whether or not it is within a predetermined lock judgment torque range T _W (T' _W ) where the clutch mechanism 48 is disengaged and the electric motor 68 is driven ( Step 202) is performed. The lock determination torque range T _W (T ′ _W ) is set between the assist stop torque value T _SP (T ′ _SP ) and the clutch engagement / disengagement torque value T ₁ (T ′ ₁ ) as shown in FIG. I am doing it.

In the electric power steering device 20, the torque value T (T ') is in the lock determination torque range T.
_{When in W} (T ' _W ), the clutch mechanism 48 is disengaged and the electric motor 68 is being driven. At this time, the worm wheel 54 forming the drive system of the electric motor 68,
The clutch mechanism 48 is disengaged and the electric motor 68 is driven, so that the clutch mechanism 48 is rotated.

When the torque value T (T ') is within the lock determination torque range _TW ( _T'W ) (step 20)
2: YES) processes the lock determination (step 204)
To do. The torque value T (T ') is the torque range T for lock determination.
When it is within _W (T ' _W ), the clutch mechanism 48 is disengaged and the electric motor 68 is driven, so that the worm wheel 54 is rotated as described above.

[0068] Therefore, the lock detector 128, the processing of the lock determination in (step 204), after the clutch mechanism 48 is disengaged _{(T SP ~T 1: T '} SP ~T' 1)
The rotation detecting means (not shown) detects the rotation of the worm wheel 54, and if the worm wheel 54 is rotating, a normal lock determination is processed. If the worm wheel 54 is not rotating, the abnormal lock is detected. Process the decision. In the lock determination process (step 204), it is determined whether the lock is normal (step 206).

Of course, the lock determination process (step 2
In 04), as described above, the electric motor 6 after the clutch mechanism 48 is disengaged (T _{SP to} T ₁ : T ′ _{SP to} T ′ ₁ ).
The current value of 8 is detected by a current detection means (not shown),
If the current value of the electric motor 68 is less than or equal to the set value, the normal lock determination can be processed, and if the current value of the electric motor 68 exceeds the set value, the abnormal lock determination can be processed.

This lock determination process (step 204)
Is judged to be normal (step 206). If the lock determination is normal (step 206: YES), a normal control process for controlling the driving force of the electric motor 68 to assist the operating force of the steering wheel 8 by the electric power steering device 20 (step 208)
Then, the process returns to the main routine (step 200) (step 210).

Abnormal lock determination (step 206: N
In the case of O), an abnormal lamp (not shown) of the electric power steering device 20 is turned on to give a warning to the driver, and the process returns to the main routine (step 200) (step 210).

Further, in the (step 202),
The torque value T (T ') is the torque range T for lock determination.
If it is outside _W (T ' _W ) (step 202: NO)
Performs a normal control process (step 208) for controlling the driving force of the electric motor 68 to assist the operating force of the steering wheel 8 by the electric power steering device 20, and returns to the main routine (step 200) (step 210). To do.

In this way, the lock detecting device 128 of the electric power steering device 20 calculates the torque value T (T ') from the displacement amount detected by the steering sensor 76 by the control unit 114, and the torque value T (T T ′) is within a predetermined torque range T _W (T ′ _W ) for lock determination in which the clutch mechanism 48 is disengaged and the electric motor 68 is being driven, processing for executing lock determination of the drive system of the electric motor 68 is performed. is doing.

As a result, this lock detecting device 128
When the steering wheel 8 is operated, the torque value T (T ′) calculated from the displacement amount detected by the steering sensor 76 has a predetermined lock determination torque range in which the clutch mechanism 48 is disengaged and the electric motor 68 is driven. T _W
By entering the (T _'W), so that the clutch mechanism 48 for each of the steering wheel 8 to practice the lock determination before the drive stop of the electric motor 68 after being disengaged.

Therefore, the lock detecting device 128 is
The lock determination can be performed during normal control, and no special actuator operation is required for the lock determination of the drive system of the electric motor 68. In addition, this lock detection device 128
By performing the lock determination during the normal control, it is possible to quickly give a warning when an abnormality is detected.

Moreover, the lock detecting device 128 is a so-called three-way type clutch mechanism 48 capable of being manually steered even when the drive system of the electric motor 68 is locked.
By providing the lock determination, the lock determination can be made gradual, and it suffices to provide an abnormal lamp that is turned on when the lock determination is abnormal, and the short time at the start of driving the electric motor 68 (assist low torque value T _{It is possible} to make a lock determination between _SP (T ' _SP ) and the clutch engagement / disengagement torque value T ₁ (T' ₁ )), and repeat this to make a comprehensive determination, both in terms of hardware and software. The structure can be simplified, the configuration can be simplified, and the cost can be reduced.

Further, in the lock detecting device 128, as described above, even if the drive system of the electric motor 68 is in the locked state,
By providing the so-called 3-way type clutch mechanism 48 capable of being manually steered, the lock determination can be loosened. Therefore, as described above, it is possible to perform the lock determination of the drive system of the electric motor 68 so as to be performed at every predetermined time t, and the number of the performed processes is smaller than the number of times the steering wheel 8 is operated. It can also be thinned out and processed. As a result, the number of lock determination processes can be reduced with respect to the number of times the steering wheel 8 is operated, and an electrically / mechanically inoperative state can be revealed, which is advantageous in terms of durability and cost. be able to.

In the first embodiment, each time the steering wheel 8 is operated, the lock determination is performed after the driving of the electric motor 68 before the clutch mechanism 48 is engaged, and in the second embodiment. The lock determination is performed every time the steering wheel 8 is operated before the drive of the electric motor 68 is disengaged after the clutch mechanism 48 is disengaged, but the first and second embodiments may be combined.

That is, each time the steering wheel 8 is operated, the lock determination is performed after the driving of the electric motor 68 before the clutch mechanism 48 is engaged, and the clutch mechanism 48 is disengaged each time the steering wheel 8 is operated. It is also possible to carry out the lock determination before the drive of the electric motor 68 is stopped after the start. In this way, by performing the lock determination at the start and end of the operation of the steering wheel 8, it is possible to make a more appropriate determination and contribute to the improvement of the accuracy of the lock determination.

[0080]

As described above, according to the present invention, in the lock detecting device of the electric power steering device, when the steering wheel is operated, the torque value calculated from the displacement amount detected by the steering sensor is detected by the clutch mechanism. By entering the predetermined lock judgment torque range in which the electric motor is driven after being disengaged, the lock mechanism is disengaged each time the steering wheel is operated and the lock judgment is performed while the electric motor is being driven. .

Therefore, the lock detecting device of the electric power steering device can perform the lock determination during the normal control, and does not require a special actuator operation for the lock determination of the drive system of the electric motor. In addition, this electric power steering device can quickly give a warning when an abnormality is detected by performing the lock determination during the normal control.

In addition, the lock detecting device of the electric power steering device is provided with the so-called 3-way type clutch mechanism that enables manual steering even when the drive system of the electric motor is in a locked state. It is only necessary to provide an abnormal lamp etc. that is turned on when the lock judgment is abnormal, and the lock judgment can be made in a short time at the start or stop of driving the motor, and this is repeated. A comprehensive judgment may be made, and the structure can be simplified in terms of hardware and software, the configuration can be simplified, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a flowchart of control by a control unit showing an embodiment of a lock detection device of an electric power steering device.

FIG. 2 is a diagram showing an assist characteristic of an electric motor based on a displacement amount (torque value) between an input shaft and an output shaft and an assist amount of the electric motor in the first embodiment.

FIG. 3 is a diagram showing assist characteristics of an electric motor according to a displacement amount (torque value) between an input shaft and an output shaft and an assist amount of the electric motor according to a second embodiment.

FIG. 4 is a circuit configuration diagram of a control unit.

FIG. 5 is a schematic configuration diagram of an electric power steering device mounted on a vehicle.

FIG. 6 is a schematic configuration diagram illustrating an operation of a steering sensor at a steering wheel neutral position.

FIG. 7 is a schematic configuration diagram illustrating an operation of a steering sensor when a steering wheel is rotated counterclockwise.

FIG. 8 is a schematic configuration diagram illustrating an operation of a steering sensor when a steering wheel is rotated clockwise.

FIG. 9 is an enlarged sectional view of a main part of the electric power steering device.

10 is a cross-sectional view taken along line XX of FIG.

11 is a sectional view taken along line XI-XI of FIG.

12 is an enlarged cross-sectional view showing a state where the clutch mechanism is disengaged at a portion indicated by an arrow A in FIG.

13 is an enlarged cross-sectional view showing a state where the clutch mechanism is engaged at a portion indicated by an arrow A in FIG.

FIG. 14 is a diagram illustrating a relationship between a displacement amount between an input shaft and an output shaft and an assist amount of an electric motor for explaining a conventional technique.

[Explanation of symbols]

 2 Vehicle 4 Front Wheel 6 Rear Wheel 8 Steering Wheel 10 Steering Column 12 Steering Gear 18 Tie Rod 20 Electric Power Steering Device 22 Input Shaft 24 Output Shaft 34 Large Diameter Portion 40 Elastic Body 46 Connecting Pin 48 Clutch Mechanism 50 Inner Cage 52 Outer Cage 54 Worm Wheel 56 Rolling Element 58 Spring 68 Electric Motor 70 Electric Motor Shaft 74 Worm Gear 76 Steering Sensor 78 Sensor Main Body 80 Sensor Shaft Part 82 Plate Member 84 Sensing Part 86 First Slider 88 Circumferential Groove 90 Second Slider 94 Guide Groove 96 Guide Shaft 98 Protrusion Edge 100 Ball hole 102 Ball 104 Sensing groove 106 Cover 110 Retainer 112 Sensing spring 114 Control unit 116 Ignition coil 118 Vehicle speed sensor 120 Generator 12 Ignition switch 124 Battery 126 Fuse 128 lock detector

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[Procedure amendment]

[Submission date] May 20, 1994

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

[Figure 4]

[Figure 5]

[Figure 6]

[Figure 7]

[Figure 8]

[Figure 9]

[Figure 10]

FIG. 11

[Fig. 12]

[Fig. 13]

FIG. 14

Claims (4)

[Claims] 1. An input shaft connected to a steering wheel of a vehicle and an output shaft connected to a steering gear are provided so as to be relatively rotatable via an elastic body, and the input shaft and the output shaft are connected to each other. When the amount of displacement due to relative rotation is less than or equal to a set value, it is disengaged from the output shaft, and when the amount of displacement due to relative rotation between the input shaft and the output shaft exceeds the set value, it is engaged with the output shaft. A clutch mechanism is provided, an electric motor is provided to interrupt the transmission of the driving force to the output shaft by the clutch mechanism, and a steering sensor is provided to detect a displacement amount and a displacement direction due to relative rotation between the input shaft and the output shaft. The steering wheel operating force is transmitted by transmitting the driving force of the electric motor to the output shaft via the clutch mechanism based on the detection signal of the steering sensor. In a lock detection device for an electric power steering device that is sist, a torque value applied between the input shaft and the output shaft is calculated from a displacement amount due to relative rotation between the input shaft and the output shaft detected by the steering sensor. If the torque value is within a predetermined lock determination torque range in which the clutch mechanism is disengaged and the electric motor is being driven, control means is provided for processing to make a lock determination of the drive system of the electric motor. A lock detection device for an electric power steering device, comprising: 2. The control means sets the assist characteristic of the electric motor such that the assist start torque value is smaller than the clutch engagement / disengagement torque value when the clutch mechanism is engaged / disengaged, and the assist stop torque value is the assist stop torque value. It is set to a characteristic that is larger than the clutch engagement / disengagement torque value, the range from the assist start torque value to the clutch engagement / disengagement torque value is set to the lock determination torque range, and a displacement amount input from the steering sensor is set. The lock detection device for an electric power steering device according to claim 1, wherein the lock detection device is a control unit that performs processing to perform lock determination of the drive system of the electric motor when the calculated torque value is within the lock determination torque range. 3. The control means has an assist characteristic of the electric motor, wherein an assist start torque value is larger than a clutch engagement / disengagement torque value when the clutch mechanism is engaged / disengaged, and the assist stop torque value is the aforesaid. It is set to a characteristic that is smaller than the clutch engagement / disengagement torque value, the range from the assist stop torque value to the clutch engagement / disengagement torque value is set to the lock determination torque range, and the displacement amount input from the steering sensor is set. The lock detection device for an electric power steering device according to claim 1, wherein the lock detection device is a control unit that performs processing to perform lock determination of the drive system of the electric motor when the calculated torque value is within the lock determination torque range. 4. The electric power steering apparatus according to claim 1, wherein the control unit is a control unit that processes lock determination of the drive system of the electric motor at predetermined time intervals. Lock detection device.