JPH04287755A - Brake system for rear two-shaft vehicle - Google Patents

Abstract

PURPOSE:To surely prohibit the feed of the brake pressure to brakes for driven wheels by properly switching a cutoff valve device at the time of traction control. CONSTITUTION:Flow controllers 300, 400, 500 are arranged in the middle of pipes from a traction control valve 200 to a cutoff valve device 100 and brakes 21R, 21L for driving wheels. The flow controllers 300, 400, 500 are constituted of check valves 301, 401, 501 and throttles 302, 402, 502, and the forward direction of a check valve 300 on the cutoff valve device 100 side is opposite to the forward direction of the other check valves 401, 501. The cutoff valve device 100 can be surely kept at the closed state during the traction control by the flow controllers 300, 400, 500.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention relates to a brake system for rear two-axle vehicles such as large trucks, and in particular has a traction control (ASR) function to prevent the drive wheels from spinning when starting or accelerating. Regarding brake technology.

0002

[Prior Art and its Problems] Generally, large vehicles have two rear axles in order to accommodate the size of the payload.
There is one. Of the two rear axles, the wheels belonging to one axle are usually the driving wheels, and the wheels belonging to the other axle are the driven wheels. Therefore, a brake system for a rear two-axle vehicle with a traction control function has a main brake device that supplies brake pressure to each brake device of both the driving wheel and the driven wheel, although individual devices may also be used. and an auxiliary brake device that supplies brake pressure to the drive wheels for traction control. In order to enable effective starting or acceleration, it is necessary to separate the brake for the driven wheels from the brake for the driving wheels among the brakes for the rear wheels during traction control. As a disconnection means for this purpose, Japanese Patent Application Laid-Open No. 63-232057 discloses a shutoff valve that prohibits the supply of brake pressure to the driven wheel brake in response to the operation of the auxiliary brake device, in the middle of the piping to the driven wheel brake. The technology for installing the device has been clarified.

However, if the brake pressure for traction control is used as a control signal for the shutoff valve device, the switching timing of the shutoff valve device will be delayed due to the influence of the length of the brake piping or resistance, causing damage to the driven wheels. The brakes will be applied. Furthermore, even if both the traction control valve and the shutoff valve device are constructed of solenoid valves, and the opening and closing of the valves are controlled by electrical or electronic signals, the shutoff valve device may not always be controlled properly due to manufacturing variations in the solenoid valves. Can not do it.

0004

OBJECTS OF THE INVENTION An object of the present invention is to provide a technique that can appropriately switch a shutoff valve device during traction control and reliably prohibit the supply of brake pressure to a brake for a driven wheel.

[0005]

[Means and operations for the purpose] In this invention, a cutoff valve device is provided in the middle of the brake pipe connecting to the driven wheel brake, so that when the auxiliary brake device for traction control starts operating, the brake pressure is not supplied to the driving wheel brake. A switching timing control means is provided which delays the release of the brake pressure of the driving wheel brake when the operation of the auxiliary brake device is completed. The switching timing control means can be configured using pneumatic control parts such as throttles and check valves, or when the traction control valve and cutoff valve device are configured with electromagnetic valves, it can be configured using an electronic control circuit. It can also be configured. In either case, since the switching timing control means acts to appropriately switch the cutoff valve device, the driven wheel brake can be reliably disconnected from the driving wheel side during traction control.

[0006]

[First Embodiment] FIGS. 1 and 2 relate to the first embodiment. First, the entire piping system will be explained with reference to FIG. 1 showing the entire brake piping diagram, and then the key points of the present invention will be clarified. The vehicle has three axles 1
There are 0, 11, and 12. Axle 10 is the front axle, and axles 11 and 12 are the rear axles. Of the two rear axles, the wheels belonging to the front axle 11 are drive wheels, and the wheels belonging to the rear axle 12
The wheels belonging to are the driven wheels. Wheel brake devices 20R and 2 are provided for each wheel of the front one axle and the rear two axles, respectively.
There are 0L; 21R, 21L; 22R, 22L. Regarding the supply of brake pressure to each wheel brake device, air pressure from the front reservoir 30 enters the front wheel brake devices 20R, 20L. The air pressure in the reservoir 30 is
followed by a relay valve 50, a pressure control valve 60, and an air over hydraulic booster 70.
through the branch pipes 40R and 40L to each brake device 2.
It reaches 0R and 20L. The relay valve 50 operates in response to depression of the brake valve 80, and signal pressure applied to the lower 80l side of the brake valve 80 through the pipe 41a is applied to the relay valve 50 through another pipe 41b. Furthermore, on the rear side, the left and right sides are independent from each other. Each rear left wheel brake device 21L, 22L has a
Air pressure is supplied from the rear left reservoir 32. The air pressure in the reservoir 32 is controlled by the piping 42, the relay valve 52 following the piping 42, and the double check valve 9.
2, the pressure control valve 62 and the air over hydraulic booster 72, and the branch pipe 43.
a, 43b to each brake device 21L, 22L. In this case, regarding the signal pressure of the relay valve 52, the air pressure of the reservoir 32 is applied to the upper 80u side of the brake valve 80 through the pipe 44, and the signal pressure is applied to the upper 80u side of the brake valve 80 through the pipe 44.
It is applied to the relay valve 52 through. The same applies to the right side of the rear as to the left side. That is,
Each rear right wheel brake device 21R, 22R has a
Air pressure is supplied from the rear right reservoir 34. The air pressure in the reservoir 34 is controlled by a pipe 46, a relay valve 54 following the pipe 46, and a double check valve 9.
4, the pressure control valve 64 and the air over hydraulic booster 74, and the branch pipe 47
a, 47b to each brake device 21R, 22R. The relay valve 54 is of a two-system type, and has two signal pressures. One is the lower 8 of the brake valve 80.
One is the air pressure from the front reservoir 30 that is applied through the 0l side, and the other is the air pressure from the rear left reservoir 32 that is applied through the upper 80u side of the brake valve 80. The one that rises earlier is involved in the actual operation. do. The front, rear left, and rear right three-channel pressure control valves 60, 62, and 64 also serve as ABS control valves for skid prevention, and are constituted by known three-way, three-position valves.

Now, there is a cutoff valve device for inhibiting brake pressure to each wheel brake device 22R, 22L on the driven wheel side during traction control, but since the rear left and right brake systems are independent, the cutoff valve device is are on each side. However, since each shutoff valve device has the same configuration, corresponding parts are given the same reference numerals here for convenience of explanation. Each cutoff valve device 100 has a branch pipe 47b
, 43b, and one of the three pipe connection ports is 1.
01 is on the air over hydraulic booster 74, 72 side, and the other 102 is the wheel brake device 22R, 22L.
On the other hand, the remaining one 103 is connected to the traction control valve 200 side. FIG. 2 shows the shutoff valve device 100
The cross-sectional structure is shown. As can be seen from FIG. 2, the shutoff valve device 100 includes a piston 1 inside a casing 110.
20, the piston 120 has a pressure chamber 130 inside.
and an atmospheric chamber 140. There is a ball 120a at one end of the piston 120, and the ball 120a moves against the valve seat 1 on the casing 110 side according to the movement of the piston 120.
10a and sit down. The piston 120 has a spring 150
During normal operation without traction control, the ball 120a separates from the valve seat 110a and transfers the brake pressure from the air over hydraulic boosters 74 and 72 to the wheel brake devices 22R and 22L.
Can be fed on the side. However, during traction control, when control pressure is received from the traction control valve 200 side, the ball 120a seats on the valve seat 110a, closing the valve. Thereby, each isolation valve device 10
0 acts to prohibit the supply of brake pressure to the wheel brake devices 22R and 22L of the driven wheels during traction control.

In this first embodiment, three flow controllers 300, 400, and 500 are provided in consideration of the fact that the piping from the traction control valve 200 to each cutoff valve device 100 is long and has a large flow resistance. . The traction control valve 200 is located at a position branching from a pipe 42 that communicates with the rear left reservoir 32. Since the interior of this traction control valve 200 includes two systems that are independent of each other, two pipes 241 and 242 extend on the output side. Both of those pipes connect to a double check valve 290, from there via a flow controller 300 to each branch pipe 241a, 242a.
It is connected to the piping connection port 103 of the shutoff valve device 100. Double check valve 290, like other double check valves 92 and 94, has a high pressure selection function. In other words, the double check valve 290
1,242, the higher one is selected, and the selected air pressure is supplied to the shutoff valve device 100 side as a control pressure. Therefore, when traction control starts on either the left or right drive wheel, the two left and right shutoff valve devices 100 close together, and it is possible to avoid the inconvenience that the left and right shutoff valve devices 100 repeatedly open and close independently. can. This is advantageous in terms of durability of the shutoff valve device 100 and the like. Further, other pipes 243a, 244a branch from the middle of the pipes 241, 242 extending from the traction control valve 200, and flow controllers 400, 50 are connected to each branch pipe 243a, 244a.
0 is placed in each. Each flow controller 40
The other end of 0,500 is a double check valve 94,9
2 are connected to the left and right brake pipes on the rear side, respectively. Here, each flow controller 300, 400
,500. They are both check valves 301, 401, 501 and throttles 302, 402, 502.
It is composed of. However, while the check valves 401 and 501 on the side communicating with the brake pipe have a forward direction from the brake pipe side toward the traction control valve 200 side, the check valve 301 on the side communicating with the cutoff valve device 100 The forward direction is the direction from the traction control valve 200 side to the cutoff valve device 100 side. Due to this connection relationship, at the start of traction control, the cutoff valve device 100 receives control pressure from the traction control valve 200 side through the check valve 301 and immediately switches to the closed state, whereas the double check valve 94
, 92 side, air pressure is slowly supplied by the action of the throttles 402, 502. Also,
At the end of traction control, double check valves 94, 92 and check valves 401, 50
The brake pressure on the brake piping side is quickly exhausted through 1, while the air pressure on the shutoff valve device 100 side is exhausted through the throttle 3.
It is slowly exhausted through 02. As a result, during traction control, the shutoff valve device 100 can be reliably closed and the supply of brake pressure to the wheel brake devices 22R and 22L of the driven wheels can be reliably prohibited.

[0009]

[Second Embodiment] FIG. 3 shows a second embodiment. In the first embodiment, a shutoff valve device 100 driven by air pressure
However, in this second embodiment, the shutoff valve device 701
, 702 are constituted by electromagnetic valves, and these are switched and controlled by an electric circuit. traction control valve 200
' is composed of two three-way, two-position type solenoid valves 201 and 202, and each of these solenoid valves 201 and 202 is connected to a drive circuit 80.
1,802. Each drive circuit 801, 8
02 is controlled by traction control signals S1 and S2 output from the electronic control unit 900. Here, ON delay timers 811 and 812 are placed in the middle of the wiring from the electronic control unit 900 to each of the drive circuits 801 and 802. On the other hand, the shutoff valve devices 701 and 702, which are two-way, two-position electromagnetic valves, are also driven by electrical drive circuits 803 and 804. Each of those drive circuits 803 and 804 also receives traction control signals S1 and S2 from the electronic control unit 900.
controlled by In the control system, OR gate 85
A 0 and OFF delay timer 820 is provided. OR gate 850 outputs two traction control signals S
1 or S2, both shutoff valve devices 701,
702 to the closed state, that is, it has the same effect as the double check valve 290 in the first embodiment. The ON delay timers 811 and 812 included in the control system on the traction control valve 200' side switch the cutoff valve devices 701 and 702 to the closed state earlier than the traction control valve 200' at the start of traction control, and The OFF delay timer 820 included in the control system on the side of the cutoff valve devices 701, 702 acts to switch the cutoff valve devices 701, 702 to the open state with a little delay compared to the traction control valve 200' when traction control ends. do. Such action allows each of the cutoff valve devices 701, 702 to be reliably held in a closed state during traction control.

0010

According to the present invention, specific switching timing control means is provided for the cutoff valve devices 100, 701, and 702 that prohibit the supply of brake pressure to the driven wheels during traction control. The device can be appropriately switched and controlled, and unnecessary braking on the driven wheels can be effectively and reliably prevented during traction control.

[Brief explanation of the drawing]

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

FIG. 2 is a sectional view showing an example of a shutoff valve device used in the first embodiment.

FIG. 3 is a control circuit diagram showing a second embodiment of the invention.

[Explanation of symbols]

21R, 21L Wheel brake device (brake device for driving wheels) 22R, 22L Wheel brake device (brake device for driven wheels) 100, 701, 702 Shutoff valve device 200, 2
00' Traction control valve 300,400
,500 Flow controller 811,812 ON
Delay timer 820 OFF delay timer

Claims (1)

[Claims] Claim 1: Out of the two rear axles, the wheels belonging to one axle are the driving wheels, and the wheels belonging to the other axle are the driven wheels.
A driving wheel brake that is installed on an axle and applies braking force to the driving wheel; a driven wheel brake that applies braking force to the driven wheel; A main brake device that supplies brake pressure to both driving wheel brakes, an auxiliary brake device that can supply brake pressure based on a command from a control circuit that monitors the idling of the drive wheels, and operation of the auxiliary brake device. A brake system for a rear two-axle vehicle having a cutoff valve device that prohibits the supply of brake pressure to the driven wheel brake device in accordance with the operation of the auxiliary brake device. 2. A switching timing control means is provided for switching the switching timing so as to precede the brake pressure supply to the brake device and delay the release of the brake pressure of the driving wheel brake device when the operation of the auxiliary brake device is completed.
Brake system for axle wheels.