JPH04201770A - Brake force holding device - Google Patents

Abstract

PURPOSE:To detect actual torque accurately further cheaply so as to release brake force of a vehicle by energizing a check valve to generate the brake force under a predetermined condition, and also, when even one of the predetermined conditions is not satisfied, deenergizing the check valve when an output of a torque sensor exceeds a maximum value. CONSTITUTION:Torsional torque of an input shaft 1 of a transmission 10 as a clutch shaft is detected by a torque sensor 2. Based on detection signals from the torque sensor 2 and the other, an electromagnetic check valve 15 is controlled by a control unit 14. That is, when the electromagnetic check valve 15 is deenergized, brake oil, fed to a wheel brake 17 through a hydraulic route 16a by already stepping a brake pedal 9, is reversed to flow through a route 16b to release brake force. On the other hand, when the electromagnetic check valve 15 is energized, a reverse flow of the brake oil is impeded with the hydraulic route 16a to hold the brake force.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a braking force holding device, and more particularly to a device for smoothly and safely releasing the braking force of a vehicle.

[Conventional technology]

When starting a vehicle stopped on a road, in conventional vehicles, the driver uses the parking brake (hat brake) with one hand to apply braking force to the vehicle and keep it at a stop, while gradually engaging the clutch. Depress the accelerator pedal. During this time, it was necessary to gradually loosen the parking brake.

However, in this case, complicated operations are required in which the brake, clutch, and accelerator are coordinated, so skill is required to perform a smooth start, which often causes the engine to stall or the vehicle to back up. .

Therefore, in Japanese Patent Application Laid-Open No. 63-1.66643, the present applicant provided a check valve and an electromagnetic on-off valve which closes the valve and maintains the braking force by energizing it in the braking fluid path, and furthermore, an engine rotation speed detecting means. The present invention proposes a device comprising: an accelerator pedal depression amount detection means; and a control means.

In this device, the control means controls the engine speed according to the preset relationship between the accelerator pedal depression amount and the engine rotation speed when the engine is under no load, and the change in the increase in the accelerator pedal depression amount detected at the time of starting up the hill. The re-engine load is detected by comparing the change in the number of changes, and if it is determined that this load is greater than a predetermined value, the value is set to 1 and the on-off valve is deenergized (
(opening the valve) and releasing the braking force that had been maintained.

Furthermore, the present applicant has proposed in Japanese Patent Application No. 1-260533 a device equipped with an electromagnetic check valve, a clutch stroke sensor, an input shaft rotation speed sensor, a gear position sensor, and a control means. In this device, the control means releases the braking force at a stroke point where the input shaft starts rotating due to clutch engagement during the clutch stroke when the gear position is neutral, and a correction amount corresponding to the clutch engagement speed is added. Learn as a point,
Under predetermined conditions, the check valve is energized to generate braking force, and when the clutch stroke reaches the braking force release point, the check valve is deenergized to release the held braking force. ing.

[Problem to be solved by the invention]

However, in the first conventional example, the relationship between the accelerator pedal depression amount and the engine rotation speed when the engine is not loaded is determined in advance to detect the engine load.
The driving force transmitted from the engine to the transmission, that is, the torque, is indirectly detected by comparing it with the change in engine speed corresponding to the change in the actual accelerator pedal depression amount. For this reason, an error occurs in the comparison calculation between the actual load and no-load conditions, resulting in low control accuracy.Furthermore, reference values are set for each accelerator sensor, engine speed sensor, engine, and transmission. There was a problem in that the cost was high because it required additional memory and the like.

In addition, in the second conventional example above, the clutch engagement speed is determined at the clutch stroke when the impact shaft begins to rotate (in other words, when the clutch engagement amount reaches a level that can transmit enough torque to the transmission to prevent the vehicle from slipping). It is necessary to learn the point at which a correction amount according to Even if the learning data is lost in the memory, there are problems in that there is a tremor caused by slipping and falling when starting up the hill, and that a clutch stroke sensor, an impact shaft sensor, a vehicle speed sensor, etc. are required, resulting in high cost.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a braking force holding device that can accurately and inexpensively detect the actual torque transmitted from the engine to the transmission and release the braking force of the vehicle.

[Means to solve the problem]

As a means for solving the above problems, the braking force holding device according to the present invention includes an electromagnetic check valve, a torque sensor that detects the torsional torque of the clutch shaft, a gear position sensor, and control means that energizes the valve to generate braking force and deenergizes the check valve when it is determined that the output of the torque sensor exceeds a maximum value when even one of the predetermined conditions is not satisfied; It is equipped with

[For production]

In the braking force holding device according to the present invention, a conventionally used torque sensor is provided on the clutch shaft, and the control means biases the check valve to generate braking force under normal predetermined conditions. After that, the value of torsional torque generated on the clutch shaft is monitored based on the output of this torque sensor.

Here, the torsional torque generated on this clutch shaft (in this case, the impact shaft) is caused by the engine's rotational torque transmitted through the clutch when the clutch starts to engage, trying to rotate the stationary input shaft. As shown in Fig. 3, it begins to increase from the clutch connection starting point A, reaches its maximum just before the input shaft starts rotating, and after the rotation starts, it increases as the rotational speed increases. At the clutch complete engagement point B, the engine torque and the input shaft rotational speed are balanced, and the torque stops decreasing, after which it becomes a constant value.

Also, at the maximum point of the above torsional torque, the engine torque transmitted to the input shaft via the clutch is
This also shows that it has become large enough to overcome the forces that try to keep the vehicle stopped (the forces that keep it from sliding when it is on the pitch).

Therefore, when the control means detects the maximum point of the above-mentioned torsional torque, the control means deenergizes the 1f magnetic check valve and opens the valve, thereby releasing the braking force smoothly and safely to prevent the vehicle from slipping. ing.

The reason why we do not adopt the method of releasing the braking force by detecting the start of rotation of the input shaft instead of detecting the maximum point of torsional torque as described above is because it is necessary to detect the rotation speed of the input shaft when the output It is also necessary to detect and constantly compare the rotation speed of the input shaft, which requires two sensors, and the start-up rotation of the input shaft correlates with the start-up rotation of the output shaft only during normal driving when the clutch does not slip. This is because.

〔Example〕

FIG. 1 is a diagram showing the hardware configuration of an embodiment of the braking force holding device according to the present invention, where l is the impact shaft of the transmission [1 (T/M) 10 as the flanch shaft, 2 is the input shaft] 1 is a torque sensor as a torsional torque detection means.

Here, this torque sensor can be one that has been used conventionally, and its configuration will be explained based on FIG. 23a and 23b are two pairs of magnetostrictive films made of amorphous alloy or the like having It is a differential amplifier that outputs the difference voltage between the conversion circuits 24a and 24b, and the two pairs of magnetostrictive films 22a, 2 due to the torsional stress generated by the torque load on the input shaft 1.
The change in the magnetic permeability of the coil 2b is detected as a change in the inductance of the coils 23a and 23b, and the magnitude and direction of the torque load are simultaneously detected by the differential output from the amplifier 25 of both coils 23a and 23b.

3 is the clutch, 4 is on when the accelerator pedal 5 is released (
6 is the parking brake switch that is turned on when the parking (hand) brake 7 is pulled and the brake is operated, and 8 is the parking brake switch that is turned on when the brake pedal 9 is pressed. 11 is a gear position sensor that detects the gear position of the transmission (T/M) 10.
The neutral switch that turns on when neutral is detected, 13 is the output shaft of the gear shift l110 (
A vehicle speed sensor that detects the speed of the vehicle from the rotation of the output shaft) 12, 14 is a sensor 2.13 and switches 4, 6, 8.1
A control unit 15 serving as a control means for inputting the detection signal of 1 sends the signal to the wheel brake 17 through a hydraulic route 16a because the brake pedal 9 has already been depressed when the output signal from the control unit 14 is deenergized. A 1-ite magnetic non-return check for braking that causes the brake oil to flow back through the route 16b to release the braking force, and when energized, prevents the backflow of the brake oil together with the hydraulic route 16a to maintain the braking force. It is a valve.

Further, 18 is a door switch that is turned on when the vehicle door (not shown) is opened, and 19 is a door switch that sounds when the door switch 18 is turned on while braking force is maintained or when the parking brake switch 6 is turned on. This is a buzzer installed in the control unit 14 that emits the sound.

It should be noted that the output signals of each sensor are A/D converted once they are input to the control unit 14, as in normal analog signal processing, and then used for control.

FIG. 2 is a diagram showing a flowchart of a program stored in advance in the control unit 14, and the operation of the embodiment of the present invention will be described below with reference to this flowchart. The braking force holding operation described below is the same control as in the conventional technology.

■Power supply and ■Operation In FIG. 2, the control unit 14 first checks whether the accelerator pedal 5 is not depressed but is released and the accelerator switch (SW) 4 is in the ON state. When it is determined that the neutral switch 11 is on (step S1), it is checked whether the neutral switch 11 is on (step S2).

When it is determined in step S2 that the neutral switch 11 is on and the vehicle is not driven, it is checked whether the brake pedal 9 is depressed and the foot brake switch 8 is on. S3).

When the brake pedal 9 is depressed, it is preferable to return the parking brake 7 and check whether the parking brake switch 6 is turned off (step S4). This means that the parking brake is a completely different system. When the driver pulls the parking brake halfway, if the wheel brake is applied by the foot brake, the holding pressure will drop due to pulp leak in the check valve 15, etc. This is because there are times when the braking condition collapses. Therefore, when the parking brake 7 is not applied and the parking brake switch 6 is off, the braking is permitted and the process proceeds to step S5.

In step S5, it is checked whether the vehicle speed signal (pulse signal) from the vehicle speed sensor 11 indicates a predetermined speed V or less. In this case, the predetermined speed is the vehicle speed sensor 11
cannot detect the speed ``0'', so a speed as close to 0'' as possible is used.

When the vehicle speed approaches 10", that is, when the vehicle is almost at a standstill, it is preferable to check whether the vehicle speed is further below a predetermined deceleration (step S6). This is because if the vehicle is braked when driving in rain or snow, the tires will slip and become locked, making it dangerous to maintain this braked state.

After this, it is diagnosed whether or not there is any abnormality in the vehicle speed sensor 11 (step S7).
When a pulse other than the intermediate level (for example, 2V) is generated, it is determined that the sensor is abnormal.

When all of the braking permissible states in steps 5l-57 are satisfied, it is preferable to check whether this state continues for a certain period of time (step S8 in the same step).
), this certain period of time means a common-sense delay time (grace) in which it can be assumed that the driver intends to maintain the braking force. Moreover, this duration can be determined more accurately in step S5 by using another delay time during which the vehicle is considered to have stopped.

After a certain period of time has elapsed in this way, the control unit 14 generates a signal to energize the braking electromagnetic check valve 15 (step S9).

Through the processing up to this point, the braking force is applied and the vehicle comes to a stop.

Tomo lαul111 Next, when starting the vehicle, the accelerator pedal 5 must be depressed and the engine must be able to drive the vehicle, so basically the accelerator switch 4 must be off or the neutral switch 11 must be turned off. If the vehicle is off, the foot brake switch 8 is off, or the vehicle speed is almost at a standstill, step S4. S6~S
8, if it is "N" in each case, it means that even one of the braking force operating conditions is not satisfied, and in this case, proceed to step SIO and read the torsional torque T of the input shaft 1 from the output of the torque sensor 2. .

Next, in order to detect the maximum value of this read torque T, that is, the point indicating that the engine torque transmitted to the input shaft via the clutch has become large enough to overcome the force that stops the vehicle. , Compare the torsional torque Ts-rich read and stored two times before each process in the routine of FIG. 2 with the torsional torque T□ read and stored one time before the same step. 51
1) When T-z≧Tfi-1, this control is immediately terminated.

On the other hand, in step Sll T1. −Z〈T
*When it is -1, the torsional torque T is increasing as shown in Figure 3, so next, the torsional torque T7- that was read one time ago is
1 and the torque T1 read this time (step 5I2).

As a result, when T7-1≧T1, this control ends as it is, but if it is determined that T, -I>T-, this indicates that the torsional torque T has reached the maximum point, so it is preferable to do so here. After checking the duration to consider that there is an intention to start (releasing the braking force) (step 513)
When this duration period has elapsed, the braking electromagnetic check valve 15 is deenergized to release the braking force (step 514), and preparations are made for starting.

Finally, if the parking brake 7 is pulled in step S4 and the parking brake switch 6 is turned on, proceed to step S13 as in the case of the accelerator switch 4, and it is assumed that the parking brake 7 has been applied. It is preferable to check the duration for

〔Effect of the invention〕

As described above, the braking force holding device of the present invention is configured to release the held braking force when the torque sensor provided on the clutch shaft detects the maximum torsional torque of the clutch shaft. It is possible to directly and reliably detect when the engine torque transmitted to the input shaft through the input shaft has become large enough to overcome the force that stops the vehicle, thereby preventing the vehicle from sliding and ensuring smooth and safe operation. Braking force can be released.

[Brief explanation of the drawing]

FIG. 1 is a hardware configuration diagram showing an embodiment of the braking force holding device according to the present invention, FIG. 2 is a flowchart of a program stored and executed in the control unit of the present invention, and FIG. FIG. 4 is a graph diagram for explaining the principle of operation of the present invention. FIG. 4 is a block diagram of the configuration of the torque sensor used in the present invention. In FIG. 1, 2 is a torque sensor, 4 is an accelerator switch, 11 is a neutral switch, 8 is a foot brake switch, 14 is a control unit, and 15 is a t-magnetic check valve for braking. In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] An electromagnetic check valve, a torque sensor that detects the torsional torque of the clutch shaft, a gear position sensor, and a device that energizes the check valve under predetermined conditions to generate braking force and at least one of the predetermined conditions is satisfied. A braking force holding device comprising: control means that deenergizes the check valve when it is determined that the output of the torque sensor has reached a maximum value when the check valve is not in use.