JPH1111291A - Operation control device for auxiliary brake - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent drive wheels from being locked when an auxiliary brake is applied. SOLUTION: An auxiliary brake (exhaust brake 30 and eddy current retarder 40) is installed in a power transmission route ranging from an engine 1 to drive wheels 6a and 6b of an vehicle. Also the amount of slippage of the drive wheels is detected by detectors 7a to 7d and 11a to 11d so as to limit a drive force braking by the auxiliary brake when the amount of slippage exceeds a first threshold level while the drive force braking is performed by the auxiliary brake. Then, when the amount of slippage lowers to a second threshold level or below (smaller than the first threshold level), a control to restart the drive force braking with the auxiliary brake is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a vehicle having an auxiliary brake such as an exhaust brake, a retarder, etc.
The present invention relates to a device for controlling the operation of the auxiliary brake.

[0002]

2. Description of the Related Art As a means for braking a vehicle, there are a drum brake and a disc brake for braking the rotation of wheels. In addition to such a brake, an auxiliary brake such as an exhaust brake and an eddy current retarder is provided. There are many vehicles. In particular, many large trucks and the like have an auxiliary brake device. Such an auxiliary brake is such that when the vehicle travels a long downhill, the driver manually operates the brake to reduce the load on the drum or the disc brake.

It is known that an auxiliary brake is incorporated in an auto cruise device and automatically operated, as disclosed in Japanese Patent Publication No. 2514461. Further, as disclosed in Japanese Patent Application Laid-Open No. 8-298703, it is also known to perform control for automatically operating an auxiliary brake according to a running state of a vehicle.

[0004]

By the way, the braking force of the auxiliary brake is generally smaller than that of a normal brake that is operated by operating the brake pedal. Wheel slip is unlikely to occur when a sudden brake is applied. However, when driving on an auxiliary brake while driving on a road surface with a low coefficient of friction such as a snow-covered road surface or an ice-burn road surface, there is a possibility that driving wheels are locked and traveling stability of the vehicle is impaired. There's a problem.

The present invention has been made in view of such a problem.
Provided is an auxiliary brake operation control device having a configuration capable of reliably preventing a drive wheel from being locked even when the auxiliary brake is operated, for example, when traveling on a road surface with a low friction coefficient. The purpose is to:

[0006]

In order to achieve the above object, according to the present invention, an auxiliary brake device is provided in a power transmission path from an engine to a drive wheel in a vehicle, and a slip amount of the drive wheel is reduced. Slip detecting means for detecting is provided, and the driving by the auxiliary braking means is performed when the slip amount detected by the slip detecting means exceeds the first threshold value while the driving force braking by the auxiliary braking means is performed. A control for restricting the force braking and thereafter resuming the driving force braking by the auxiliary braking means when the slip amount detected by the slip detecting means becomes equal to or less than a second threshold value (<first threshold value). And an auxiliary brake operation control means for performing the operation.

Accordingly, when the auxiliary brake is operated while traveling on a road surface having a low coefficient of friction, when the slip amount of the drive wheel increases, the operation of the auxiliary brake is limited, and the slip of the drive wheel becomes larger. This prevents the driving wheels from locking and the running stability from being reduced. When the slip of the driving wheel becomes small, the auxiliary brake operation is restarted, and the auxiliary brake operation is performed as efficiently as possible.

A second aspect of the present invention has an auxiliary brake means and a slip detection means, and has an auxiliary brake operation control means, and the auxiliary brake operation control means performs driving force braking by the auxiliary brake means. When the slip amount detected by the slip detection means exceeds the threshold value, the driving force braking amount by the auxiliary brake means is gradually reduced, and thereafter, when the slip amount becomes equal to or less than the threshold value. Control is performed to gradually increase the amount of driving force braking by the auxiliary braking means.

A third aspect of the present invention has an auxiliary brake means and a slip detection means, and also has an auxiliary brake operation control means, and the auxiliary brake operation control means performs driving force braking by the auxiliary brake means. While the slip amount detected by the slip detecting means exceeds the first threshold value, the driving force braking amount by the auxiliary brake means is gradually reduced, and the slip amount is smaller than the first threshold value. When this happens, the driving force braking amount at that time is held, and thereafter, the slip amount is set to the second threshold value (<1st threshold value).
Control is performed to gradually increase the amount of braking of the driving force by the auxiliary brake means from when the value becomes equal to or less than the threshold value.

In the second and third aspects of the present invention, if the slip amount of the drive wheels is increased to some extent while the auxiliary brake is being operated, the driving force control amount of the auxiliary brake is gradually reduced. Braking force changes slowly. For this reason, the change in the driving force of the auxiliary brake gradually increases and decreases, and the locking of the driving wheels hardly occurs.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a drive system in a vehicle provided with an auxiliary brake operation control device according to the present invention. In this vehicle, an engine 1 is mounted on a front portion of a vehicle body, and a transmission 2 is provided at a rear end of the engine 1. A propeller shaft 3a is connected to an output shaft of the transmission 2, and after the output of the engine 1 is shifted by the transmission 2,
The power is transmitted to the propeller shaft 3a. The propeller shaft 3a passes through the eddy current retarder 40 and passes through the propeller shaft 3a.
b. The propeller shaft 3b is connected to a differential mechanism 4, where the driving force from the engine is split into two parts and transmitted to the left and right rear wheels 6a, 6b via the left and right axle shafts 5a, 5b. As a result, the rear wheels 6a,
6b is driven and the vehicle travels. Thus, in this vehicle, the rear wheels 6a, 6b are driving wheels, and the front wheels 8a, 8b are non-driving wheels (idle wheels).

As shown, the rear wheel and the front wheel each have a pulse generator 7a which rotates integrally with each wheel.
To 7d, and pulse pickup devices 11a to 11d are attached to the vehicle body to face these. Therefore, when each wheel rotates, a pulse signal proportional to the rotation is detected by the pulse pickup devices 11a to 11d. The pulse signal detected in this way is sent to the control unit 10.

In this vehicle, an exhaust brake 30 which opens and closes an exhaust passage of an engine to obtain a braking force by an engine braking action as an auxiliary brake, a propeller shaft 3
An eddy current retarder 40 is provided in the middle of the a and 3b to obtain a braking force proportional to the rotation of the propeller shafts 3a and 3b by an eddy current action. The operations of the exhaust brake 30 and the eddy current retarder 40 are controlled by the control unit 10.

Here, the exhaust brake 30 is provided with an opening / closing valve in an exhaust passage (for example, an exhaust pipe) of the engine and closing the opening / closing valve so that the engine acts as a compressor to perform a braking operation. Is a kind of The operation of the opening / closing valve is performed by the control unit 10. The control is control for selecting either opening or closing of the opening / closing valve, that is, ON / OFF control. This exhaust brake 3
0 is already widely used in vehicles equipped with a diesel engine, etc., and is well known, so that the description of its configuration and the like is omitted.

The eddy current retarder 40 is configured, for example, as shown in FIGS. This eddy current retarder 4
0 is a fixed housing 41 fixedly held on the vehicle body 19;
A bracket 42 coupled thereto, the bracket 42
A fixed portion composed of a plurality of electromagnets 51 to 58 and the like attached to the
b, the shaft coupling 45 being rotatably held through the flange 45, and the flange coupling 4 connected to both ends of the shaft 45.
6a and 46b, and a rotating unit including a rotating drum 47 and the like coupled to the flange coupling 46a.

The bracket 42 constituting the fixing portion has a cylindrical portion, and eight electromagnets 51 to 58 are radially attached to the outer peripheral surface of the cylindrical portion at substantially equal intervals by bolts 51c to 58c. Each of the electromagnets 51 to 58 has a core member 51b to 58b made of a ferromagnetic material such as iron.
And eddy current generating coils 51a to 58a wound around the core members 51b to 58b.

On the other hand, flange couplings 46a and 46b are connected to both ends of a shaft 45 constituting a rotating part by splines coaxially with the shaft 45.
7 is bolted to the flange coupling 46a. The cylindrical portion of the rotating drum 47 is the electromagnet 10
In this state, the outer peripheral side end faces of the core members 51b to 58b are located in close proximity to the inner peripheral surface of the rotating drum 47. A plurality of radiating fins 47a are formed on the outer periphery of the cylindrical portion of the rotating drum 47, and a plurality of radiating fins 47a are formed in the center of the cylindrical portion so as to penetrate in the radial direction to discharge the internal high-temperature air. A hole 47b is formed.

In the eddy current retarder having the above-described configuration, the flange couplings 46a and 46b are connected to the transmission output shaft or a propeller shaft connected thereto, and the rotating portion rotates together with the output shaft and the propeller shaft. In this state, when the eddy current generating coils 51a to 58a of the electromagnets 51 to 58 are energized, a magnetic flux is generated in the core members 51b to 58b in the axial direction (radial direction of the eddy current retarder), and this magnetic flux is extended. Rotating drum 47
Across the cylindrical part of. Therefore, an eddy current is generated in the cylindrical portion of the rotating drum 47, and a braking torque opposite to the rotating direction of the rotating drum 47 is generated by the action of the eddy current, whereby the rotation is braked.

As can be clearly understood from such a configuration, the magnitude of the braking torque is proportional to the strength of the magnetic flux, and is proportional to the magnitude of the current supplied to the eddy current generating coils 51a to 58a.
Therefore, the magnitude of the braking torque can be arbitrarily controlled by controlling the supplied current. That is, in the case of the eddy current retarder 40, not only ON / OFF control but also
It is possible to control to set an arbitrary value from ON (100% braking) to OFF (0% braking). Further, energization of a total of eight eddy current generating coils 51a to 58a is turned on.
-By selectively performing the OFF control, it is also possible to perform control for setting the braking torque in eight stages.

Next, the operation control (operation control by the control unit CU) of the operation control device for the auxiliary brake described above will be described with reference to FIG. 4 and FIG. FIG. 4 shows the driving wheels (rear wheels 6a, 6b) when the vehicle is running with the auxiliary brake activated (ON state).
The auxiliary brake is deactivated due to the increase in the slip amount (OF
FIG. 5 shows a case in which the control of F) is performed, and this control will be described based on the operation control flow of the auxiliary brake shown in FIG.

Here, an auxiliary brake (exhaust brake 30) is used.
And only one or both of the eddy current retarder 40 and the eddy current retarder 40) are shown.
When the auxiliary brake is turned on, the control shown in the flow of FIG. 5 is started. First, in step S1, the off timer T (0FF) is set to 0 and the lock timer T (LOC
K) = 0. And the pulse pickup devices 11a to
The rotation speed of each wheel is calculated based on the pulse signal detected by 11d (step S2).

Here, the front wheels (non-driving wheels) 8a, 8b, even if the friction coefficient of the running road surface is low, unless a normal brake for directly braking the rotation of the wheels (a brake operated by operating a brake pedal) is operated. Does not lock and rotates in proportion to the vehicle speed. For this reason, the actual vehicle speed V is calculated based on the rotation speeds of the front wheels 8a and 8b thus determined.
1 can be obtained. This actual vehicle speed V1 is shown by a solid line in FIG. 4, and since the auxiliary brake is ON, the vehicle speed V1
Decreases almost linearly with time. on the other hand,
Since the braking force of the auxiliary brake acts on the rear wheels 6a and 6b, which are the driving wheels, when the friction coefficient of the traveling road surface is low, the braking force is rapidly reduced by the braking force. The reference wheel speed V2 obtained from the low-speed rotation speeds of the rear wheels 6a and 6b that change in this manner is also indicated by a solid line in FIG. From the difference between the actual vehicle speed V1 and the reference wheel speed V2, the slip amount of the drive wheel is calculated.
A SLIP is obtained (step S2). Note that this slip amount
FIG. 4 shows the change over time of SLIP.

Next, the slip amount SLIP obtained as described above
Is compared with a first threshold value TH1 (step S3). Note that a predetermined value (for example, a vehicle speed of 4 KM / H or a vehicle speed of 1/10 of the actual vehicle speed) is set as the first threshold value TH1, and here, two points in FIG. As shown by the chain line, it is compared whether the reference wheel speed V2 is lower than the vehicle speed set to the vehicle speed lower than the actual vehicle speed V1 by the first threshold value TH1. If the slip amount SLIP is smaller than the first threshold value TH1, that is, if there is not much slip, the process proceeds to step S4, and the lock timer T (LOCK) is reset to 0. On the other hand, when the slip amount SLIP exceeds the first threshold TH1, a value obtained by adding 1 to the current lock timer T (LOCK) is updated as a new value. Thereby, for example, in the state before the time t1 in FIG.
(LOCK) = 0 and the slip amount SL at time t1
Lock timer T (LOCK) when IP exceeds the first threshold TH1
= 1 is set.

Then, the process proceeds to a step S6, wherein the slip amount SL
IP is compared with the second threshold value TH2, and the OFF timer T (OFF)> 0
It is determined whether or not the lock timer T (LOCK)> TH3. Note that the second threshold value TH2 is set to a value slightly smaller than the first threshold value TH1 (for example, a value smaller by 1 KM / H). Here, if the condition of SLIP> TH2 is satisfied and the condition of T (OFF)> 0 or T (LOCK)> TH3 is satisfied, the process proceeds to step S8, where the current off timer T (OFF) is set.
Is updated as a new value. If the above condition is not satisfied, the process proceeds to step S7 and the off timer T (O
FF) = 0. Then, in step S9, it is determined whether or not the off timer T (OFF)> 0, and T (OFF) =
If 0, proceed to step S11 to turn on the auxiliary brake
Operate (continue as is if currently ON), T (OFF)
If> 0, proceed to step S10 to turn on the auxiliary brake
Set to FF.

Thus, before the time t1 in FIG. 4, the off timer T (OFF) = 0 and the lock timer T (LOCK) = 0, so that the auxiliary brake is kept ON. Then, at time t1, the slip amount SLIP
Exceeds the first threshold TH1, the off timer T (OFF) = 0 at the time of step S6, and the lock timer T (LOC)
Since K) = 1, the off timer T (OFF) = 0 is maintained, and the auxiliary brake is maintained ON. That is, immediately after the slip amount SLIP exceeds the first threshold value TH1, the auxiliary brake is still kept ON.

Thereafter, the flow returns to step S2 to execute the next control routine. At this time, the slip amount SLIP is still the first
If the threshold value TH1 is exceeded, 1 is added to the lock timer in step S5, and T (LOCK) = 2. When T (LOCK)> TH3, the control routine proceeds from step S6 to step S8, where 1 is added to the off timer, and T (OFF) = 1. This allows
The process proceeds from step S9 to step S11, and the auxiliary brake is turned off.

As can be seen from the above description, the slip amount
The auxiliary brake is not turned off immediately at the time t1 when the SLIP exceeds the first threshold TH1, and the auxiliary brake is not activated at the time t2 when it is determined that the SLIP still exceeds the first threshold in the next control routine. It is turned off. Thus, when the slip amount SLIP slightly exceeds the first threshold value and becomes small immediately, the auxiliary brake is continuously turned on to prevent the braking force from becoming insufficient.

Thereafter, at time t3, the slip amount SLIP
Is smaller than the first threshold TH1, the lock timer T (LOCK) is reset to 0 in step S4.
Since the OFF timer T (OFF) is incremented by 1 in step S8, the process proceeds to step S11, and the auxiliary brake remains OFF. When the slip amount SLIP becomes smaller than the second threshold value TH2 at time t4, the off timer T (OFF) is reset to 0 in step S7, the process proceeds to step S10, the auxiliary brake is turned on, and braking by the auxiliary brake is restarted. Is done.

In the above, the auxiliary brake is turned ON / OF.
Although the case where the F operation control is performed has been described, the braking force can be arbitrarily controlled when the eddy current retarder 40 is used as the auxiliary brake, and the control in such a case will be described with reference to FIGS. 6 and 7.

This control is performed according to the flow of FIG. 7, and this flow shows the control in a state where the eddy current retarder 40 is turned ON. First, in step S21, the rotational speed of each wheel is detected, and the slip amount SLIP is calculated. This calculation is performed in the same manner as in step 2 in FIG. Then, in step S22, the slip amount SLIP is compared with the fourth threshold value TH4. If SLIP> TH4, the flow proceeds to step S24 to reduce the retarder output by a predetermined amount, and if SLIP ≦ TH4, the flow proceeds to step S23. Control is performed to increase the retarder output by a predetermined amount. Hereinafter, this control routine is repeated at predetermined time intervals.

When such control is performed, as shown in FIG. 6, the reference wheel speed V2 decreases with respect to the actual vehicle speed V1, and when the slip amount SLIP exceeds the fourth threshold value TH4 at time t1, the retarder Control for reducing the output is started. Thereby, the retarder output gradually decreases every time the control routine is repeated, and as shown in FIG. 6, the retarder output gradually decreases as long as the slip amount SLIP exceeds the fourth threshold TH4. The repetition interval of the control routine is very short, for example, about 10 ms. Thereafter, when the slip amount SLIP becomes equal to or less than the fourth threshold value TH4 at time t2, control for increasing the retarder output is started, and the retarder output gradually decreases. The same control is performed every time the slip amount SLIP exceeds the fourth threshold value TH4.

As shown in FIG. 8, the fifth threshold value TH
The fifth and sixth threshold values TH6 (<TH5) are set, and the retarder output is gradually reduced as long as the slip amount SLIP exceeds the fifth threshold value TH5. As long as the value falls below the fifth threshold value TH5 as long as it is between the sixth threshold value TH6, the retarder output is held, and thereafter, control is performed to decrease the retarder output from the time the value falls below the sixth threshold value TH6. You may do it. In the case of this control, the retarder output is gradually reduced from time t1 to time t2, and the retarder output (time t2) from time t2 to time t3.
2 is kept constant, and from time t3 to time t4
, The retarder output is gradually reduced, the retarder output (output at time t4) is kept constant from time t4 to time t5, and the retarder output is gradually increased from time t5.

[0033]

As described above, according to the present invention,
When the driving force braking by the auxiliary brake means is being performed, the driving force braking by the auxiliary braking means is limited when the slip amount exceeds the first threshold value. (<1st threshold value) Since the control for restarting the driving force braking by the auxiliary braking means is performed when the driving wheel becomes less than or equal to (the first threshold value), the driving of the driving wheel is performed by operating the auxiliary brake when driving on a road surface having a low friction coefficient. When the slip amount increases, the operation of the auxiliary brake is limited, the slip of the drive wheels is prevented from further increasing, and it is possible to prevent the drive wheels from locking and the running stability from being reduced. . However, when the slip of the driving wheel becomes small, the auxiliary brake operation is restarted, and the auxiliary brake operation is performed as efficiently as possible.

According to the second and third aspects of the present invention,
While the driving force braking by the auxiliary braking means is being performed, while the slip amount detected by the slip detecting means exceeds the threshold value, the driving force braking amount by the auxiliary braking means is gradually reduced. Since the control for gradually increasing the driving force braking amount by the auxiliary brake means is performed when the slip amount becomes equal to or less than the threshold value, the braking force of the auxiliary brake can be gradually changed, and the locking of the driving wheels can be performed. Effective and effective auxiliary brake operation control can be performed without causing the occurrence.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a drive system of a vehicle including an auxiliary brake operation control device according to the present invention.

FIG. 2 is a front view showing a configuration of an eddy current retarder.

FIG. 3 is a cross-sectional view illustrating a configuration of an eddy current retarder.

FIG. 4 is a graph showing a change over time in vehicle speed and the like when the auxiliary brake operation control according to the first embodiment of the present invention is performed.

FIG. 5 is a flowchart showing an auxiliary brake operation control content according to the first embodiment of the present invention.

FIG. 6 is a graph showing a change over time in vehicle speed and the like when an auxiliary brake operation control according to a second embodiment of the present invention is performed.

FIG. 7 is a flowchart showing an auxiliary brake operation control content according to a second embodiment of the present invention.

FIG. 8 is a graph showing changes over time in vehicle speed and the like when an auxiliary brake operation control according to a third embodiment of the present invention is performed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 4 Differential mechanism 6a, 6b Rear wheel (drive wheel) 8a, 8b Front wheel (non-drive wheel) 10 Control unit 30 Exhaust brake 40 Eddy current retarder

Continued on the front page (72) Inventor Shin Yoshida 1-6-6, Tsukimino, Yamato-shi, Kanagawa Prefecture Inside Tokyo Parts Industry Co., Ltd. (72) Inventor Koji Kondo 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Industrial Co., Ltd. Within the company (72) Inventor Go Go, 33-3-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation

Claims (3)

[Claims] 1. An auxiliary brake means for braking a driving force in a power transmission path from an engine to a driving wheel of a vehicle, a slip detecting means for detecting a slip amount of the driving wheel, and a driving force by the auxiliary braking means. When the braking is being performed, when the slip amount detected by the slip detecting means exceeds a first threshold value, the driving force braking by the auxiliary braking means is limited, and thereafter, the braking is performed by the slip detecting means. When the detected slip amount is equal to the second threshold value (<
And an auxiliary brake operation control means for performing control to restart the driving force braking by the auxiliary brake means when the value becomes equal to or less than a first threshold value. 2. An auxiliary brake means for braking a driving force in a power transmission path from an engine to a driving wheel in a vehicle; a slip detecting means for detecting a slip amount of the driving wheel; and a driving force by the auxiliary braking means. While the braking is being performed, while the slip amount detected by the slip detecting means exceeds a threshold value, the driving force braking amount by the auxiliary braking means is gradually reduced, and thereafter, the slip detecting And an auxiliary brake actuation control means for performing control to gradually increase the amount of driving force braking by the auxiliary brake means when the slip amount detected by the means becomes equal to or less than the threshold value. Operation control device. 3. An auxiliary braking means for braking a driving force in a power transmission path from an engine to a driving wheel of a vehicle, a slip detecting means for detecting a slip amount of the driving wheel, and a driving force by the auxiliary braking means. While the braking is being performed, while the slip amount detected by the slip detecting means exceeds the first threshold value, the driving force braking amount by the auxiliary braking means is gradually reduced, and the slip amount is reduced. When the value becomes smaller than the first threshold value, the driving force braking amount at that time is held, and thereafter, when the slip amount becomes equal to or less than the second threshold value (<first threshold value), the auxiliary brake is applied. And an auxiliary brake operation control means for performing control to gradually increase the driving force braking amount by the means.