JPH08132843A - Control device for braking auxiliary device - Google Patents

Abstract

PURPOSE: To increase braking force in deceleration and stopping of a vehicle by installing an air spring for adjusting ground pressure of a driving shaft, detecting operation of a braking device, and controlling operation of the air spring. CONSTITUTION: A braking auxiliary device 500 using an air spring 505 is mounted on a driving shaft of rear two shafts, ground pressure of a driving shaft 200 is increased in deceleration and stopping of a vehicle to increase traction in deceleration. A control device 800 supplies air to the air spring 505 when a service brake or an exhaust brake is operated, and exhausts air when the service brake is released.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a braking assist device mounted on a rear two-axle vehicle.

[0002]

2. Description of the Related Art FIG. 7 is an explanatory view showing an outline of a vehicle having two rear axles. A large vehicle generally designated by reference numeral 1 has a front axle 21 at a front portion of a frame 10 and a front tire. 21a is supported. The rear part has two axles 31 and 32 and supports tires 31a and 32a, respectively. Rear two axes 31, 32
Is supported by the frame 10 via the suspension 40, and the load 50 is mounted on the frame 10. Therefore,
The total weight WG of the vehicle 1 including the load 50 is equal to the front tire 21a.
The load WF applied to the rear tires 31a and 32a and the load WR applied to the rear tires 31a are supported by the road surface G. 2 at the rear
By equipping the axles 31 and 32 of the book, the load WR supported by the entire rear part is equal to the load WR supported by the rear front shaft 31.
F and a load WRR supported by the rear rear shaft 32. Therefore, it is possible to configure a vehicle having a larger loaded load while suppressing the maximum load applied to one shaft.

In a rear two-axle vehicle, the rear front shaft 31 is a drive shaft that transmits the driving force from the engine, and the rear rear shaft 32 is a driven shaft that does not transmit the driving force. A so-called 6x2 that simplifies and drives two of the six wheels
It is widespread to compose vehicles. In this 6 × 2 vehicle, the drive tire 31a needs to generate sufficient propulsive force. Therefore, the axial load WR applied to the tire 31a
For F, a load sufficient to generate a necessary propulsive force between the tire and the road surface needs to be distributed. When the load is loaded, the tire 31a can generate a necessary braking force if the axial load WRF applied to the drive shaft 31 is sufficiently large and the road surface friction coefficient is also large. However, when the vehicle is empty with no load, a sufficient load WRF is not distributed to the drive shaft 31, or when the friction coefficient of the road surface is small, the tire 31a cannot obtain a sufficient braking force with the road surface G. Occurs. In particular, on a road surface having a small friction coefficient, the tire 31a may slip to cause inconvenience in braking.

[0004]

DISCLOSURE OF THE INVENTION The present applicant has filed Japanese Patent Application No.
As No. 184528, a starting assist device for a vehicle that drives one of the two rear axles was proposed. The invention of the above-mentioned application is provided with an air spring that adjusts the ground pressure of the drive shaft, detects a change in the shaft load with a level sensor, and controls the operation of the air spring to reduce the driving force when the vehicle starts. It will improve. However, this starting aid device
Since the axial load sensor tries to turn on and off the starting assist device, there is a problem that it is not suitable for obtaining a sufficient braking force when the friction coefficient of the road surface is small.
The present invention provides a braking assist device that solves the above-mentioned inconvenience.

[0005]

The control device of the present invention is a vehicle equipped with a braking assist device for a vehicle having an air spring on the drive shaft of the rear two shafts, and detects the operating state of the service brake. Means, or means for detecting the operating state of the exhaust brake, an air supply source for supplying compressed air to the air spring, a first valve provided in the air pipe for supplying air to the air spring, and an air spring A second valve for exhausting the air and a control means for controlling the first valve and the second valve.

[0006]

When the control means detects that the service brake or the exhaust brake operates, the control means opens the first valve to supply air to the air spring, and when the service brake or the exhaust brake becomes inactive, The second valve is opened to exhaust the air of the air spring.

[0007]

FIG. 4 is a plan view of an essential portion of a vehicle equipped with a braking assistance device for carrying out the present invention, FIG. 5 is a configuration diagram of a trunnion type suspension equipped with the braking assistance device of the present invention, and FIG.
[Fig. 4] is a front view of a drive shaft portion.

FIGS. 4 to 6 show an outline of a braking assist device which is installed in a vehicle having a trunnion type suspension and which increases a braking force when the vehicle is braked. The vehicle has frames 10 arranged on the left and right of the vehicle body, and supports a drive shaft 200 and a driven shaft 300 via a trunnion type suspension. A propeller shaft 60 connected to an engine and a transmission arranged in the front part of the vehicle transmits power to a differential gear mechanism installed in a differential gear case 70 integrated with a drive shaft 200. The trunnion suspension has a trunnion bracket 110 fixed to the lower surface of the frame 10, and the trunnion bracket 1
A central portion of the leaf spring 130 is supported on a trunnion shaft rotatably attached to the shaft 10.

The leaf spring 130 is a laminated leaf spring, and is actually constructed by laminating several to ten leaf springs. The drive shaft 200 has a cylindrical casing 210 in which the drive shaft is rotatably mounted, and drive shaft tires 250 are attached to both ends of the drive shaft. Generally, two drive shaft tires 250 are mounted on each side, four in total. Drive shaft 2
A sliding sheet 220 is provided on the upper portion of the housing 210 of 00 to receive one end of the leaf spring 130.
The leaf spring 130 generates a spring force that presses the drive shaft 200 toward the road surface. A spring retainer 230 is provided on the outside of the sliding sheet 220.

A first torque rod is attached to the lower portion of the housing 210 of the drive shaft via a bracket. This first torque rod is a trunnion bracket 1
It is connected to the second torque rod via a connecting member penetrating through 10. The driven shaft 300 does not transmit the driving force, and rotatably supports the driven shaft tire 350. Driven shaft tire 3
Two 50s are generally installed on one side and four on both sides, but one on each side may be provided.

The central portion of the drive shaft housing 210 projects in the vertical direction to accommodate the differential gear case 70. Bracket 2 is provided on the top of this upper protrusion.
60 is provided and the third torque rod 150 is connected. Since the trunnion type suspension 100 is configured as described above, by selecting the distance between the center of the trunnion shaft and the center of the drive shaft 200, and the distance between the center of the trunnion shaft and the center of the driven shaft 300, it is possible to apply the force to both shafts. The load ratio can be selected. Also, the drive shaft 20
0 and the driven shaft 300 circularly move with radii R ₁ and R ₂ , and the distance between the axes changes between D and D 1.

The braking assist device to which the present invention is applied is disposed above the drive shaft 200. A braking assistance device, generally designated by the reference numeral 500, comprises an air spring 505 and its mounting structure. The air spring 505 includes a diaphragm 510 and a piston member 520 disposed below the diaphragm 510.
And an upper plate 530 disposed above the diaphragm 510. The lower part of the diaphragm 510 is attached to the bracket on the drive shaft side. Diaphragm 510
The upper part of is attached to the bracket on the frame side.

For the frame 10 of the vehicle, for example, a channel material having a U-shaped cross section is used, and a frame-side bracket mounting member 570 is fixed to the inside of the frame. A bracket 560 having a lower opening is integrally provided with the mounting member 570, and an upper plate 530 of the air spring 505 is housed and fixed in the bracket 560. The air supply port 540 of the air spring 505 penetrates the bracket 560 and projects upward.

The air supply port 540 is connected to a compressed air supply source through an air supply pipe described later. Large vehicles are equipped with an air compressor and a high-pressure tank for assisting clutches and brakes, so that this compressed air supply source can be used. When the compressed air is not sent to the air spring 505, the drive shaft 200 and the driven shaft 300 are applied with the axial load at the same ratio as that of a normal trunnion suspension. When compressed air is sent to the air spring 505, the diaphragm portion 510 expands,
The drive shaft 200 is biased toward the road surface. This urging force increases the ground contact pressure applied to the drive shaft tire 250, and the braking force generated between the tire and the road surface also increases.

Therefore, when the vehicle is decelerated or stopped, a sufficient braking ability can be obtained by operating the braking assist device. The air spring, which is a component of the braking assist device, is susceptible to damage because the diaphragm part is made of a flexible material. Therefore, the air spring is arranged inside the frame of the vehicle and is covered with a bracket for protection. Further, in the trunnion type suspension, the housing is rotated around the center line of the axle due to the vertical movement of the axle. This rotation causes a displacement between the upper support portion of the air spring and each support portion. However, by disposing the air spring above the housing of the drive shaft, the influence of this displacement can be suppressed to a minimum.

The rear two-axle vehicle includes a first rear axle 200 and a second rear axle 200.
It has a rear axle 300. The first rear axle, which is arranged closer to the front axle, has a casing 210 that contains an axle,
It has a differential gear case 70 and constitutes a drive shaft. The second rear axle 300 has a casing 310,
Configure a driven shaft that does not transmit driving force. Second rear axle 30
Of course, 0 can be used as the drive shaft.

FIG. 1 is an explanatory view showing the outline of the control device of the present invention. The control device for the braking assist device, which is generally denoted by reference numeral 800, has an air tank 810, and the air in the air tank 810 is the first control valve A812 and the check valve 8
14, sent to the air spring 505 of the braking assist device 500 via the pipe 820 to increase the ground pressure of the drive shaft 200. The CPU 850, which is a control unit, is activated by the operation switch 860, takes in signals from the exhaust brake switch 864, the foot brake switch 862, the accelerator switch 868, and the clutch switch 866, and outputs the first valve A812 and the second valve A812. Control valve B 840. The first valve A 812 controls the supply of air to the pipe 820, and the second valve B 840 controls the pipe 820.
It is for exhausting the air inside.

FIG. 2 is a flow chart showing the control processing of the service brake of the control device 800 of the present invention. The process started in step S10 detects whether or not the footbrake switch is on in step S11. The footbrake switch is turned on when the footbrake pedal is depressed, and thus the service brake is activated at this time. If the footbrake switch is on, the process proceeds to step S12 and the first valve 812
(A valve) is opened and air is sent to the air spring 505. When it is detected in step S13 that the valve 812 has been opened for a certain period of time, the valve 812 is closed in step S14. As a result, the air spring expands, the braking assist device is activated, and the process ends. When it is detected in step S11 that the foot brake switch is off, that is, the foot brake is not stepped on and the service brake is not operating, the second valve 840 (B valve) is detected in step S20.
Is opened and the air in the air spring 805 is exhausted. Step S
When it is detected in 21 that the valve 840 is opened for a certain period of time, the valve 840 is closed in step S22. This deactivates the function of the braking assistance device.

FIG. 3 is a flow chart showing an exhaust brake control process as another embodiment of the control device of the present invention. This control process is almost the same as the control process shown in the flowchart of FIG. 2, but it is detected in step S40 whether or not the exhaust brake switch is on, and if it is on, the process proceeds to step S41, and if it is off. Go to step S20. The process after step S20 is the same as the process in FIG.
In step S41, the state of the clutch switch is detected, and if it is on, that is, if the clutch is in the engaged state, the process proceeds to step S42, and if the clutch switch is off, the process returns to step S40. In step S42, the accelerator state is detected by the accelerator switch. If the accelerator switch is on, the accelerator pedal is released (not depressed), the process proceeds to step S12, and if the accelerator switch is off, the process returns to step S40. The process after step S12 is similar to the process of FIG.

[0020]

As described above, according to the present invention, one of the two rear shafts is used as a drive shaft, and an air spring is provided on this drive shaft to activate the air spring when the vehicle is decelerated or stopped to thereby reduce the ground pressure. In a vehicle equipped with an increasing braking assist device, when it is detected that the vehicle is in a braking state, the braking assist device is automatically activated, and when the vehicle is not in the braking state, the braking assist device is deactivated. . Therefore, the driver only has to turn on the operation switch, and the driver does not operate when it is not needed, so that the durability of the device is improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a control device of the present invention.

FIG. 2 is a flowchart of control processing of the control device of the present invention.

FIG. 3 is a flowchart of control processing of the control device of the present invention.

FIG. 4 is a plan view of a vehicle equipped with a braking assistance device.

5 is a side view of FIG.

FIG. 6 is a front view of a drive shaft.

FIG. 7 is an explanatory diagram showing an outline of a vehicle having two rear axles.

[Explanation of symbols]

 1 1A Vehicle 10 Frame 20 Cross Beam 60 Propeller Shaft 65 Parking Brake 70 Differential Gear Case 100 Trunnion Type Suspension 110 Trunnion Bracket 120 Trunnion Shaft 130 Leaf Spring 140, 142, 150, 152 Torque Rod 200 Drive Shaft 210 Drive Shaft Housing 300 Driven Shaft 310 Driven shaft housing 500 Braking auxiliary device 505 Air spring 510 Diaphragm 520 Piston 530 Top plate 540 Compressed air supply port 550 Drive shaft side bracket 560 Frame side bracket 570 Mounting member 800 Control device 810 Air tank 812 First valve 840 Second valve 850 CPU

Claims (2)

[Claims] 1. A rear axle having two rear axles, the front axle side of the two rear axles being the drive axle, the other axle being the driven axle, and being mounted on the drive axle to increase the ground pressure of the tire of the axle. In a vehicle including a braking assist device having an air spring, a means for detecting an operating state of a service brake, an air supply source for supplying compressed air to the air spring, and an air supply port provided in an air pipe for supplying air to the air spring. A first valve, a second valve for exhausting air from an air spring, and a control unit for controlling the first valve and the second valve are provided, and the control unit detects that the service brake is activated, When the first valve is opened to supply air to the air spring and the service brake is deactivated, the second valve
The control device of the braking assist device, characterized in that the valve of the above is opened to exhaust the air of the air spring. 2. The vehicle has two rear axles, one of the two rear axles being the front axle side and the other axle being the driven axle, which is mounted on the drive axle to increase the ground pressure of the tire of the axle. In a vehicle equipped with a braking assist device having an air spring, means for detecting the operating state of an exhaust brake, an air supply source for supplying compressed air to the air spring, and air provided for the air spring in the air pipe. A first valve, a second valve that exhausts air from the air spring, and a control unit that controls the first valve and the second valve are provided, and the control unit detects that the exhaust brake operates, Open the first valve to supply air to the air spring,
A control device for a braking assist device, wherein a second valve is opened to exhaust air from an air spring when the exhaust brake is deactivated.