JPH06211123A - Auxiliary brake device of vehicle - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent brake lock by the auxiliary brake device of the vehicle. [Structure] Auxiliary braking means (exhaust braking section 16, electromagnetic retarder section 17 and power retarding section 18) for reducing the driving force of the rear wheel R, and estimating means for estimating the magnitude of frictional resistance between the road surface and the rear wheel R. 13 and a controller 14 for reducing the braking force of the auxiliary braking device when it is determined that the braking force of the auxiliary braking device is excessive based on the signal from the estimating device 13 The device 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auxiliary braking device for vehicles.

[0002]

2. Description of the Related Art An auxiliary brake device mounted on a large vehicle such as a truck is composed of, for example, an exhaust brake part, an electromagnetic retarder part, a power retard part, etc., and reduces the driving force transmitted to driving wheels to reduce the braking force. Is generated. That is, when the driver turns on the auxiliary brake switch, the exhaust brake part and the power tard part generate resistance to reciprocating motion of the engine piston, and
The electromagnetic retarder unit generates a resistance force of the rotational movement of the driving force transmission shaft, absorbs a part of the driving force transmitted to the driving wheels, and brakes the driving wheels.

The braking force by the auxiliary braking device is set weaker than the braking force by the service braking device, but by using it together with the service braking device, the size and durability of the service braking device can be reduced. be able to.

[0004]

However, the above-mentioned conventional auxiliary braking device operates when the driver operates a switch, and a similar braking force is exerted regardless of the magnitude of the frictional resistance between the road surface and the wheels. generate. The frictional resistance between the road surface and the wheels changes depending on various conditions such as the road surface and the vehicle speed.
Therefore, for example, if the auxiliary brake device is operated while a so-called empty truck is traveling on a road having a small friction coefficient in relation to the wheels, that is, a low μ road, a weak brake of only the auxiliary brake device is generated. Even with the force, this braking force may become larger than the friction resistance, and in such a case, there is a problem that the driving wheels are brake-locked and traveling stability deteriorates.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an auxiliary brake device for a vehicle capable of preventing the brake lock of the drive wheels.

[0006]

In order to achieve the above object, according to the present invention, auxiliary braking means for reducing the driving force of driving wheels, and the magnitude of frictional resistance between a road surface and driving wheels are estimated. An auxiliary braking device for a vehicle is configured to include an estimating unit and a controller that reduces the braking force of the auxiliary braking unit when it is determined that the braking force of the auxiliary braking unit is excessive based on the signal from the estimating unit. It is also.

[0007]

When the braking force is large with respect to the frictional resistance between the drive wheel and the road surface, the drive wheel is locked. The controller estimates the magnitude of the frictional resistance between the traveling road surface and the drive wheels via the estimation means, and compares the magnitude of this frictional resistance with the magnitude of the braking force of the drive wheels by the auxiliary braking means.
When it is determined that the braking force of the auxiliary braking device is excessive, the braking force of the auxiliary braking device is reduced to avoid the brake lock of the driving wheels.

[0008]

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows an embodiment of an auxiliary braking device to which the present invention is applied. An auxiliary braking device 10 for reducing the driving force transmitted from the engine 1 to a rear wheel R, which is a driving wheel, is an auxiliary braking device, a road surface. This auxiliary brake means is composed of a μ sensor 13, a controller 14, etc., and is provided with an exhaust brake unit 16, an electromagnetic retarder unit 17, and a power retard unit 18.

The exhaust brake portion 16 is provided with an opening / closing valve in the exhaust pipe of the engine 1 to reduce the passage area in the exhaust pipe to increase the engine exhaust pressure and obtain a braking force. The exhaust brake unit 16 generates a braking force F1. The electromagnetic retarder unit 17 includes, for example, a rotor that rotates integrally with a propeller shaft and a coil that is fixed to the vehicle body and applies a magnetic field to the rotor. The electromagnetic retarder unit 17 converts the rotational energy of the rotor into heat energy and releases it. It is to gain strength. The electromagnetic retarder unit 17 generates a braking force F2.

The power tard part 18 cuts the fuel of the engine 1 and adjusts the valve timing and the like to generate a positive pressure in the combustion chamber when the piston rises, and a negative pressure in the cylinder when the piston descends to generate a braking force. Is what you get. The power tard part 18 has a braking force F.
3 is generated. The controller 14 is composed of a microcomputer, and has a storage device such as ROM / RAM, an input / output device, and the like. A road surface μ sensor 13, an auxiliary brake switch 20, a brake pedal switch 22, a cancel switch 23, etc. are electrically connected to the input side of the controller 14.

The road surface μ sensor 13 is used as an estimating means for estimating the magnitude of frictional resistance between the traveling road surface and the wheels. The road surface μ sensor 13 is, for example, fixed to the front of the vehicle body facing the road surface and detects the light reflection state of the road surface to estimate the friction coefficient between the road surface and the wheel, that is, the so-called road surface μ. . The auxiliary brake switch 20 is provided on the operation panel of the driver's seat, and is turned on by the driver when operating the auxiliary brake device 10. The auxiliary brake switch 20 that has been turned on supplies an on signal to the controller 20. The brake pedal switch 22 is arranged in a brake pedal mechanism (not shown) of the service brake device, and supplies an ON signal to the controller 20 when the brake pedal is depressed. Further, the cancel switch 23 is provided on the operation panel of the driver's seat and is turned on when the driver does not wish to execute the auxiliary brake control program described later.
Then, the cancel switch 23 that has been turned on supplies an on signal to the controller 20. The vehicle speed sensor 24 is a sensor that detects the vehicle speed V.

On the other hand, an exhaust brake unit 16, an electromagnetic retarder unit 17, and a power retard unit 18 are electrically connected to the output side of the controller 14. Therefore, the controller 14 can individually operate and release the exhaust brake unit 16, the electromagnetic retarder unit 17, and the power retard unit 18, and can reduce the braking force as an auxiliary braking unit.

The magnitudes of the braking forces F1, F2 and F3 of the exhaust brake unit 16, the electromagnetic retarder unit 17 and the power retard unit 18 are stored in advance in the storage device of the controller 14. An auxiliary brake control program is stored in the storage device of the controller 14. The controller 14 executes this control program when the auxiliary brake switch 20 is turned on to operate the auxiliary brake means, and prevents the brake lock of the rear wheel R.

The auxiliary brake control program will be described below with reference to FIG. First, in step S32, the controller 14 determines whether or not the cancel switch 23 is turned on. When the driver does not turn on the cancel switch 23,
The determination result is negative, and the controller 14 performs step S
Proceed to 34.

In step S34, the controller 14
Calculates the braking force of the auxiliary braking device 10 as a whole based on the operating state of the auxiliary braking device. For example, when all of the exhaust brake unit 16, the electromagnetic retarder unit 17, and the power retard unit 18 are operating, the braking force of the auxiliary brake device 10 as a whole is a value (F1 + F).
2 + F3), and when the exhaust brake unit 16 and the power retard unit 18 are activated and the electromagnetic retarder unit 17 is deactivated, the braking force of the auxiliary brake device 10 as a whole is calculated as a value (F1 + F3). It

Next, the controller 14 executes step S3.
In step 6, the release level n is determined according to the value of the estimated road surface μ from the road surface μ sensor 13. For example, the value of the road surface μ is
When it is larger than the predetermined value A (μ> A), the release level n is set to the value 0. Further, the value of the road surface μ is a predetermined value A
The release level n is set to the value 1 when the value is equal to or less than the predetermined value B (A ≧ μ> B). Furthermore, the road surface μ
Is larger than the predetermined value B and larger than the predetermined value C (B ≧ μ> C), the release level n is set to the value 2. Furthermore, when the value of the road surface μ is less than or equal to a predetermined value C (C ≧
μ), the release level n is set to the value 3. Thereby, the release level n can be set according to the size of the road surface μ.

After this, the controller 14 proceeds to step S3.
8, the operation of the auxiliary braking means is operated according to the release level n. For example, when the release level n is set to the value 0, the operations of the exhaust brake unit 16, the electromagnetic retarder unit 17, and the power retard unit 18 are maintained. Therefore, the braking force in this case is the value (F1 + F2 + F3)
Is set to. Further, when the release level n is set to the value 1, only the operation of the electromagnetic retarder unit 17 is released and the operations of the exhaust brake unit 16 and the power retard unit 18 are maintained. Therefore, the braking force in this case is the value (F
1 + F3). Further, when the release level n is set to the value 2, the operation of the power retard unit 18 in addition to the electromagnetic retarder unit 17 is released, and the exhaust brake unit 1
The operation of 6 is maintained. Therefore, the braking force in this case is reduced to the value F1. Then, when the release level n is set to the value 3, the operation of the exhaust brake unit 16 in addition to the electromagnetic retarder unit 17 and the power retard unit 18 is also released, so that the operation of all the auxiliary braking means is performed. To release. As a result, the magnitude of the braking force of the entire auxiliary braking device can be reduced according to the release level n.

Table 1 shows the relationship among the road surface μ, the release level n, and the auxiliary braking means.

[0019]

[Table 1] The order of releasing the operation of the auxiliary braking device according to the release level n is not limited to this order. Also,
Depending on the release level n, only one of the exhaust brake unit 16, the electromagnetic retarder unit 17, and the power retard unit 18 may be operated. In this case, it is desirable to consider the magnitude relationship among the braking forces F1, F2, F3 of the exhaust brake unit 16, the electromagnetic retarder unit 17, and the power retard unit 18.

After this, the controller 14 proceeds to step S4.
It proceeds to 0 and determines whether or not to end this control program. The controller 14 ends this control program when the service brake device is operated, when the vehicle is stopped, and when the operation of the auxiliary brake device 10 is released. Here, the controller 14 recognizes the operation of the service brake device when the ON signal is supplied from the brake pedal switch 22. Further, the controller 14 detects the vehicle speed V based on the signal from the vehicle speed sensor 24, and recognizes the stop of the vehicle when the vehicle speed V becomes 0 (or a low speed sufficiently close to 0). Further, the controller 14 recognizes the release of the operation of the auxiliary brake device 10 when the auxiliary brake switch 20 is turned off.

If the determination result in step S40 is negative, the controller 14 returns to step S32 and repeats the above-mentioned control. On the other hand, in step S40, if any of the ending conditions is satisfied and the determination result is affirmative, the controller 14 ends the execution of this control program.

In step S32, when the cancel switch 23 is detected to be turned on and the determination result is affirmative, the controller 14 ends the execution of this control program. In this case, it is possible to prevent the controller 14 from automatically reducing the braking force of the auxiliary braking means regardless of the driver's will. In the present embodiment, the road surface μ sensor 13 is used as an estimation means for estimating the magnitude of the frictional resistance between the traveling road surface and the wheels.
The value of the road surface μ was estimated by detecting the light reflection state of the road surface, and the magnitude of the frictional resistance between the traveling road surface and the wheels was estimated.As a method of estimating the magnitude of this frictional resistance, It is not limited to. For example, road surface μ sensor 1
Instead of 3, the sensor for detecting the deceleration during braking is provided, while the deceleration when the driving wheels are brake locked is experimentally obtained, and the experimental value is stored in advance in the storage device of the controller 14. The road surface μ may be estimated by comparing the deceleration detected by the sensor with the stored deceleration. Further, a special sensor for estimating the road surface μ may be omitted and the road surface μ may be obtained by a known calculation method. Known calculation methods include, for example, the following calculation formula.

Μ = B / W-I / W * V 'where B is the braking force, W is the wheel weight, I is the moment of inertia of the wheel, and V'is the wheel deceleration. It is desirable that the values of the braking force B, the wheel weight W, and the wheel inertia moment I be experimentally obtained and stored in advance in the storage device of the controller 14.

Further, in the present embodiment, the cancel switch 23 is provided in the driver's seat to prevent the automatic release of the auxiliary braking means irrelevant to the driver's intention.
The cancel switch 23 is not always necessary. Further, the auxiliary brake device 10 may be configured by providing a pilot lamp on the operation panel of the driver's seat. In this case,
It is desirable that the controller 14 turn on the pilot lamp after executing step S38, and turn off the pilot lamp after the determination result of steps S32 and S40 is affirmative.

[0025]

As described above, according to the present invention, the auxiliary braking means for reducing the driving force of the driving wheels, the estimating means for estimating the magnitude of the frictional resistance between the traveling road surface and the driving wheels, and the estimating means. When the vehicle determines that the braking force of the auxiliary braking means is excessive based on the signal from the vehicle, the auxiliary braking device of the vehicle is configured with a controller that reduces the braking force of the auxiliary braking means. Even when the vehicle is running on a low μ road in an empty state, there is an excellent effect that the brake lock of the drive wheels by the auxiliary brake device can be prevented.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of an auxiliary brake device for a vehicle according to the present invention.

2 is a flowchart of an auxiliary brake control program executed by the controller of FIG.

[Explanation of symbols]

 10 Auxiliary brake device 13 Road surface μ sensor 14 Controller 16 Exhaust brake part 17 Electromagnetic retarder part 18 Power retard part F Front wheel R Rear wheel

Claims (1)

[Claims] 1. An auxiliary braking means for reducing a driving force of a driving wheel, an estimating means for estimating a magnitude of frictional resistance between a traveling road surface and a driving wheel, and a brake for the auxiliary braking means based on a signal from the estimating means. An auxiliary braking device for a vehicle, comprising: a controller that reduces the braking force of the auxiliary braking means when it is determined that the force is excessive.