JPH06239219A - Brake system for rear two axle vehicle - Google Patents

Abstract

PURPOSE:To prevent confinement of pressure fluid in a pressure releasing device at completion of traction control. CONSTITUTION:A pressure releasing device 100 contains a low pressure reservoir 120 which can receive pressure fluid from a retarder 22R for driven wheel, and a pressure releasing valve 110 which communicates the retarder 22R for driven wheel to the low pressure reservoir 120. Further, in addition, a check valve 170 to connect the low pressure reservoir 120 side to a shut-off valve 50 side is contained in the device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake system for a rear two-axle vehicle such as a heavy-duty truck, which has a traction control function for preventing idling of drive wheels at the time of starting or accelerating. Yes, it relates to the one that prevents pressure from remaining in the driven wheel brake during traction control.

[0002]

[Prior Art and its Problems] Generally, in a large vehicle,
There are two rear axles to accommodate the size of the payload. After that, of the two axles, the wheel that normally belongs to one axle is the drive wheel and the wheel that belongs to the other axle is the driven wheel. Therefore, a brake system for a rear two-axle vehicle having a traction control function, which may be used as an individual device, has a main brake device that supplies brake pressure to each brake of both the driving wheel and the driven wheel. An auxiliary braking device that supplies braking pressure to the drive wheels for traction control. In order to enable effective starting or acceleration, it is necessary to separate the brakes for the driven wheels from the brakes for the driven wheels among the brakes for the rear wheels during traction control. Japanese Patent Laid-Open No. 63-232057 or Japanese Utility Model Laid-Open No. 1-64278 discloses a disconnection means for that purpose, in the middle of piping to the brake for the driven wheel, in accordance with the operation of the auxiliary brake device. The technology for providing a shutoff valve device that prohibits the supply of

However, at the time of traction control, the shut-off valve device shuts off the driven wheel brake device side, so that residual pressure may occur on the driven wheel brake device side. For example, when starting a vehicle from a stopped state with a brake applied on an uphill road, if the brake release operation is quickly switched to the accelerator operation, traction control may be started. The shut-off valve device closes before the pressure of the driving wheel brake is sufficiently reduced, and residual pressure is generated on the driven wheel brake side, which causes drag of the brake and disturbance of control, which hinders starting. .

As a technique for solving such a residual pressure problem, the applicant has proposed a method of providing a pressure slackening device between the shut-off valve device and the driven wheel brake device according to the operation of the auxiliary brake device (special feature: Japanese Patent Application No. 3-263227). Further examination of the technology according to this proposal revealed the following room for improvement. The pressure relief device includes, for example, a low pressure reservoir capable of receiving pressure from the driven wheel brake, and a pressure release valve for communicating the driven wheel braker with the low pressure reservoir in response to operation of the auxiliary brake device. The pressure release valve switches from the shut-off position to the open position at the start of traction control, and switches from the open position to the shut-off position at the end of traction control. In practice, the pressure relief valve is delayed, for example, by several msec from the operation of the shutoff valve device at the start of the traction control, and by several m at the end of traction control.
Sec, each works.

The low-pressure reservoir is, for example, a small capacity (for example, about 10 cc), which is about the amount of hydraulic fluid of the driven wheel brake.
However, depending on the traction control, it is not possible to discharge all the pressure fluid released from the brake for the driven wheel to the low-pressure reservoir to the outside of the low-pressure reservoir by the time the pressure relief valve switches to the shut-off position. There is a risk that some of the pressurized fluid will be trapped inside and remain. When such traction control is repeatedly performed, the residual amount of the pressure fluid in the low pressure reservoir increases, and in the worst case, the reservoir capacity is reached, and the pressure release device loses its release function.

[0006]

OBJECTS OF THE INVENTION It is an object of the present invention to prevent pressure fluid from being contained in a pressure relief device at the end of traction control, in other words, to allow the pressure relief device to return to its initial state. To provide.

[0007]

According to the present invention, basically, the pressure relief device is provided with a check valve which allows the flow of the pressure fluid toward the main or auxiliary braking device side and prohibits the flow in the opposite direction. I have to. Preferably, the check valve is located between the low pressure reservoir (reservoir) and the shut-off valve device to prevent pressure from the main or auxiliary braking device side from flowing into the reservoir while preventing the reverse flow. Always forgive. Therefore, at the end of traction control, even if some of the pressure fluid remains in the reservoir, the residual pressure flows through the passage including the check valve to the main or auxiliary braking device side, and the reservoir is always It will return to the initial state.

[0008]

[First Embodiment] FIG. 1 is a brake piping diagram showing a first embodiment of the present invention. The piping system will first be described in general with reference to FIG. 1, and then the points of the present invention will be clarified. The vehicle has three axles 10,1
There are 1 and 12. Axle 10 is the front axle, axle 11,
Two of 12 are rear axles. A pair of left and right wheels (or a group of wheels) 10L, 10 is provided on each axle 10, 11, 12.
There are R; 11L, 11R; 12L, 12R. Among the two rear axles, wheels 11L and 11R belonging to the front axle 11 are drive wheels, and wheels belonging to the rear axle 12 are driven wheels. Front 1-axle and rear 2-axle wheels 10L, 10R; 11
L, 11R; 12L, 12R, respectively, wheel braking device (brake) 20L, 20R; 21L, 21
Of course, R; 22L and 22R are provided.

The compressed air, which is the source of the braking force, is supplied to the main air tank 25 and the front air tank 2 communicating with it.
It is stored in the 5F and the rear air tank 25R. The operation of the brake is performed along with the operation of the brake valve 27. The brake valve 27 is an upper 27a.
And the lower 27b are two-system valves including two mutually independent systems, the lower 27b side belongs to the front side brake pipe 30, and the upper 27b side belongs to the rear side brake pipe 40. The front brake pipe 30 is common to the left and right wheel brake devices, whereas the rear brake pipe 40 is independent from each other on the left and right.

In the front brake pipe 30, an anti-skid pressure control valve 34 and an air-over hydraulic booster 35 are connected in series after the relay valve 28. The anti-skid pressure control valve 34 is composed of a known solenoid valve device including a shutoff valve and a slack valve, and the left and right wheels 10L and 10R on the front side based on a command from an electronic control unit (not shown) that constitutes a control circuit. To prevent skids. In order to detect the rotational state of the left and right wheels 10L and 10R, pulse wheels 32 and 32 'are provided on the wheels 10L and 10R, respectively, and speed sensors 31 and 31' are provided on the adjacent portions. Speed sensor 3
The detection signals from 1, 31 'are input to the electronic control unit, and the electronic control unit receives the detection signals and determines whether or not each wheel 10L, 10R is idling (or skid), and based on that, pressure control is performed. Send a command to valve 34. Also, air over hydraulic booster 35
Converts the air pressure into hydraulic pressure, and the left and right wheels 10L, 10R
The brake pressure is supplied to the brake devices 20L and 20R belonging to.

On the other hand, the left and right rear brake pipes 40 are independent of each other, but those on the left and right following the relay valve 29 have the same structure. Therefore, for convenience of description, only the devices belonging to one of the left and right will be described, and the same reference numerals will be used for the respective devices belonging to the other, and detailed description thereof will be omitted. A double check valve 47 having a high-pressure selection function, a pressure control valve 44, and an air-over hydraulic booster 45 are sequentially connected to the rear-side brake pipe 40, and a brake pressure from the air-over-hydraulic booster 45 is branched to a branch pipe 48. The brake devices 21R and 22R belonging to the respective wheels 11R and 12R are added through the respective wheels. The pressure control valve 44 also serves as both an antiskid control valve and a traction control valve. Therefore, on the rear side, the front wheels 11 that are drive wheels are used.
Pulse ring 42 and speed sensor 41 for R
Is provided. The detection signal from the speed sensor 41 is input to the electronic control unit in the same manner as described above, and the electronic control unit determines whether or not the wheel 11R is idling based on the input signal, and the pressure control valve 44 and the traction pressure are determined. A control command is sent to the switching valve 46. The traction pressure switching valve 46 is located between the input side of the brake valve 27 and the double check valve 47, and is normally in a closed state, but switches to an open state during traction control. Further, a shutoff valve device 50 is provided in the middle of the branch pipe 48, and during traction control,
Brake device 21R and driven wheel 12 for drive wheel 11R
The communication between the R and the brake device 22R is cut off.

In the first embodiment, a pressure slackening device 100 is provided between the shutoff valve device 50 and the brake device 22R for the driven wheel 12R in the middle of the branch pipe 48. The pressure release device 100 has a function of releasing the brake pressure applied to the driven wheel 12R during traction control. The pressure relief device 100 includes, for example, a pressure release valve 1 including a two-position solenoid valve including a communication position and a cutoff position.
10 and a low pressure reservoir 120 that receives the pressure at which the pressure relief valve 110 opens. The control command for the pressure release valve 110 itself is usually obtained from the electronic control unit as in the shutoff valve device 50. Left and right drive wheels 11L, 11R
Since the traction control is independently performed, the pressure release valve 110 itself needs to be provided on the left and right independently. However, the independent pressure relief valves may be mechanically integrated, or the low pressure reservoir 120 may be integrated. Also, one low-pressure reservoir 120 itself can be used for both right and left sides. The pressure release valve 110 is preferably operated with no time delay with respect to the traction pressure switching valve 46 and the shutoff valve device 50. Therefore, in order to improve the responsiveness, in the full-air type braking device, the pilot pressure bypassed from the traction pressure switching valve 46 may be used to give a command to the pressure release valve.

Further, here, the check valve 170 is arranged at a specific position with respect to the pressure slackening device 100. The check valve 170 includes a low pressure reservoir 120 and a pressure release valve 110.
And a branch pipe 48 that connects the shutoff valve device 50 and the brake device 22R. Therefore, even if the pressure fluid released from the driven-wheel-side brake device 22R is partially confined in the low-pressure reservoir 120 depending on the traction control situation, the pressure fluid is supplied to the check valve 170. It can be effectively returned to the air-over-hydraulic booster 45 side through the pipeline including the above.

[0014]

[Second Embodiment] A second embodiment is a shutoff valve device 50, a pressure release valve 110 and a check valve 17 in the first embodiment.
0, and the low-pressure reservoir 120 is also unitized, and the unit valve 200 has these plural functions. Therefore, in the unit valve 200, the parts corresponding to each other are denoted by reference numerals with 2 added to the heads of the numbers, that is, 250, 2110, 2170, 2120 to facilitate understanding of the corresponding relationship between the respective elements. 2 shows the piping portion on the rear side, and FIG. 3 shows the sectional structure of the unit valve 200.

The unit valve 200 includes a base 201 having a convex cross section and a cylindrical body 202 integrated with the base 201.
And a solenoid coil 203 fitted on the outer circumference of the tubular body 202, and a cover 204 surrounding the outer circumference of the solenoid coil 203 and the tubular body 202. Base 201
The driven wheel side braking device 22R and the shutoff valve device 25.
A passage 231 that communicates with 0 and a passage 232 that connects the air over hydraulic booster 45 side and the shutoff valve device 250 are formed. Further, inside the cylindrical body 202, a low pressure reservoir 2120 including a piston 241 and a weak spring 242 on one side, a pressure release valve 2110 also serving as a check valve 2170 on the other side, and a shutoff valve device 250 are respectively configured. Both the pressure release valve 2110, which also serves as the check valve 2170, and the shutoff valve device 250 mainly include balls 233 and 234, and these balls are fixed to each end of the movable body 235. The movable body 235 is movable in the tubular body 202 in the axial direction, but normally,
The ball 233 is seated by the spring 236, and the ball 234 is seated.
Are in a disengaged state, which causes the check valve 2170
The pressure release valve 2110, which also functions as the valve, is closed (shut off), and the shutoff valve device 250 is open (communication). On the other hand, when the solenoid coil 203 is excited during the traction control, the movable body 235 moves to reverse the movement. The movable body 235 is provided with passages 237a and 237b that connect the pressure release valve 2110 side also serving as the check valve 2170 and the shutoff valve device 250 side. This second
In this embodiment, since the same function as in the first embodiment can be obtained and the unit valve 200 is used,
Easy to install parts such as valves.

[0016]

[Third Embodiment] FIG. 4 shows a rear pipe portion of a third embodiment. As can be seen from FIG. 4, the third embodiment has a simple configuration in which the check valve 3170 is provided in parallel with the shutoff valve device 350. The pressure relief device for eliminating the residual pressure on the driven wheel side is simplified, and a check valve 317 is provided.
0 and a pressure release source on the air over hydraulic booster 45 side. The function of pressure relief is a little inferior to those of the first and second embodiments, but has an advantage in cost and size reduction.

[0017]

According to the present invention, the pressure slackening device 100 is provided between the shutoff valve device 50 and the brake device 22R, which is a brake for the driven wheel, according to the operation of the auxiliary brake device for traction control. By this, the problem that residual pressure is generated in the driven wheel side brake during traction control can be solved, and since the check valves 170, 2170, 3170 are arranged in the pressure slackening device, the slackening function is It can be effectively secured.

[Brief description of drawings]

FIG. 1 is a diagram showing an entire piping system of a first embodiment of the present invention.

FIG. 2 is a diagram showing a main part of a piping system according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view showing an example of a unit valve used in the second embodiment.

FIG. 4 is a diagram showing a main part of a piping system according to a third embodiment of the present invention.

[Explanation of symbols]

 11R, 11L Drive wheel 12R, 12L Driven wheel 50, 250, 350 Shutoff valve device 100 Pressure relief device 110, 2110 Pressure release valve 120, 2120 Low pressure reservoir 170, 2170, 3170 Check valve

Claims (3)

[Claims] 1. A rear two-axle having two wheels of a rear axle as driving wheels and wheels of the other axle as driven wheels, mounted on a rear two-axle vehicle to apply a braking force to the driving wheels. A driving wheel brake, a driven wheel braker for applying a braking force to the driven wheel, and a main brake pressure supply / discharge device for both the driving wheel braker and the driven wheel braker according to a driver's operation. A brake device, an auxiliary brake device capable of supplying and discharging a brake pressure based on a command from a control circuit that monitors the idling of the drive wheels, and a brake to the driven wheel brake device according to the operation of the auxiliary brake device. A brake system for a rear two-wheeled vehicle, comprising: a shut-off valve device for prohibiting pressure supply; and a pressure slackening device for escaping the pressure in the driven wheel brake when the auxiliary brake device is activated, wherein the pressure slackening device is , A brake system for a rear two-wheeled vehicle having a check valve for allowing the flow of the pressure fluid toward the main or auxiliary braking device side and prohibiting the flow in the opposite direction. 2. The pressure slackening device further connects a reservoir capable of receiving pressure fluid from the driven wheel brake device and the driven wheel brake device in communication with the reservoir in response to the operation of the auxiliary brake device. The brake system for a rear two-wheeled vehicle according to claim 1, further comprising a pressure release valve, wherein the reservoir is connected to the main or auxiliary brake device side of the driven wheel brake device via the check valve. 3. The pressure slackening device includes a communication path that connects the main or auxiliary brake device side of the shutoff valve device and the driven wheel brake device side, and the check valve is provided in the communication path. The brake system for a rear two-wheel vehicle according to claim 1.