JPH10230726A - Vehicle with start auxiliary device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the slip of a vehicle owing to the air pressure reduction after the parking, by reducing the ground pressure to a normal value when a parking brake is operated, in a vehicle furnishing a start auxiliary device of the vehicle to increase the ground pressure of a driving shaft. SOLUTION: To a driving shaft of rear side two shafts, a start auxiliary device 500 using air springs 505 is furnished, and the ground pressure of a driving shaft 200 is increased in the starting time and the like of the vehicle, so as to increase the traction at the starting time. A control device 800 detects the pressures of a high pressure detecting switch 872 and a low pressure detecting switch 850 according to the ON and OFF of an operation switch 872, and when the air in the air springs 505 is short, a valve 820 is opened for a short time to send the air to the air springs 505. By such a constitution, the consumption of the air can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art FIG. 9 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 shaft 21 at a front portion of a frame 10 and a front tire. 21a is supported. The rear portion has two axles 31, 32, and supports tires 31a, 32a, respectively. Rear two axes 31, 32
Is supported by the frame 10 via the suspension 40, and a load 50 is mounted on the frame 10. Therefore,
The total weight WG of the vehicle 1 including the load 50 is the front tire 21a.
And the load WR on the rear tires 31a and 32a is distributed and supported by the road surface G. 2 at the rear
By equipping the axles 31 and 32, the load WR supported by the entire rear portion is equal to the load WR supported by the rear front shaft 31.
F and the load WRR supported by the rear rear shaft 32. Therefore, it is possible to configure a vehicle having a larger load while holding down the maximum load applied to one shaft.

In a rear two-axle vehicle, the rear front shaft 31 is a drive shaft for transmitting the driving force from the engine, and the rear rear shaft 32 is a driven shaft for not transmitting the driving force. A so-called 6x2 that simplifies and drives two of the six wheels
It has become widespread to construct vehicles. In this 6 × 2 vehicle, the driving tire 31a needs to generate a sufficient propulsive force. Therefore, the axial load WR applied to the tire 31a
F needs to be distributed with a load sufficient to generate the necessary propulsion force between the tire and the road surface. When a load is being loaded, the axial load WRF applied to the drive shaft 31 is sufficiently large, and the tire 31a can generate a necessary propulsive force. However, when there is no load, a sufficient load WRF is not distributed to the drive shaft 31, and a situation occurs in which the tire 31a cannot obtain a sufficient propulsive force with the road surface G. In particular, when the vehicle starts or on a road surface having a small friction coefficient, the tire 31a may slip and cause a problem in starting.

The present applicant has proposed in Japanese Patent Application Laid-Open Nos. Hei 8-118935 and Hei 8-118933 a start assist device for a vehicle that drives one of the two rear shafts. The invention of the above publication comprises an air tank, an air spring, an intake magnetic valve, an exhaust magnetic valve, a high pressure detection switch, a low pressure detection switch, and a control unit. When the axle load increases, the pressure in the air spring is detected at a high pressure. The air is filled up to the set pressure of the switch (temporarily 6.5 kg / cm ² ), and when the axle load is not increased, the set value of the low pressure detection switch (tentatively 1.
2 kg / cm ² ).
In a 25-ton vehicle equipped with this start-up assist device, when not in operation, for example, the WRF is almost equal, but when the device is activated, the WRF increases by 1200 kg and the WRR is 950
Kg. Also, the WF is reduced by 150 kg.

[0005]

However, (1) In order to keep the air pressure in the air spring at a low pressure or a high pressure, when the air spring is filled with air up to a set pressure, a "supply / exhaust magnet" is required. If you take the method of `` keeping the tick valve completely closed and keeping the pressure '', the air in the air tank is not consumed at all, but the air in the air spring is affected by the vibration of the vehicle etc.
It leaks little by little, and the pressure drops.

(2) In order to keep the air pressure in the air spring constant at a low pressure or a high pressure, the value of the pressure switch is detected linearly, and when the pressure is lower than the set pressure, the air supply valve is opened and When the pressure is high, open the exhaust valve and adjust the pressure. '' Whenever the pressure in the air spring fluctuates due to the vibration of the running vehicle, air is supplied and exhausted, A lot of air is consumed. And so on. The present invention provides a control device for a start assist device that achieves the above-described object.

[0007]

According to the present invention, there is provided a vehicle provided with a start assist device, comprising a vehicle speed sensor for detecting a vehicle speed, a level sensor for detecting a load on an axle, an air supply source for supplying compressed air to an air spring. A first valve provided in the air pipe to supply air to the air spring, a second valve to exhaust air from the air spring, a pressure sensor for detecting the internal pressure of the air spring, and when the starting assist device is operated Opening the first valve until the internal pressure of the air spring reaches a first predetermined value, and when the starting assist device is not operating, the second valve until the internal pressure of the air spring reaches a second predetermined value smaller than the first predetermined value. And a control unit that opens the valve of the control unit,
When the vehicle is stopped and the start assist device is operating and the internal pressure of the air spring is equal to or less than the first predetermined value, or when the vehicle is stopped and the start assist device is not operating and the internal pressure of the air spring is equal to or less than the second predetermined value, A start assist device for opening one valve for a predetermined time is provided.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 4 to 6 show an outline of a start assist device which is mounted on a vehicle having a trunnion type suspension and increases the driving force when the vehicle starts. The vehicle has frames 10 arranged on the left and right sides of the vehicle body, and supports a drive shaft 200 and a driven shaft 300 via trunnion type suspensions.

A propeller shaft 60 connected to an engine and a transmission arranged at the front of the vehicle transmits power to a differential gear mechanism provided in a differential gear case 70 integrated with the drive shaft 200. The trunnion type suspension has a trunnion bracket 110 fixed to a side surface of the frame 10, and a central portion of the leaf spring 130 is supported thereon. The right and left trunnion brackets 110 are connected by a trunnion shaft 120.

The leaf spring 130 is a laminated leaf spring, and is actually formed by stacking several to about ten leaf springs. The drive shaft 200 has a drive shaft rotatably disposed in a cylindrical casing 210, 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, that is, four in total. Drive shaft 2
The sliding sheet 220 is provided on an upper part of the housing 210 of the first spring and receives one end of the leaf spring.
The leaf spring 130 generates a spring force that presses the drive shaft 200 toward the road surface. A spring retainer 230 is provided outside the sliding sheet 220.

In order to position the drive shaft 200 and the driven shaft 300 in the front-rear direction, the drive shaft 200 and the trunnion bracket 110 are connected by torque rods 140 and 150,
The driven shaft 300 and the trunnion bracket 110 are connected by torque rods 142 and 152. The driven shaft 300 does not transmit the driving force, and rotatably supports the driven shaft tire 350. The driven shaft tire 350 is generally equipped with two tires on one side and four tires on both sides, but it is also possible to use one tire on each side.

The central portion of the drive shaft housing 210 projects vertically to accommodate the differential gear case 70. At the top of this protruding part is a bracket 2
60 are provided, and the third torque rod 150 is connected. Since the trunnion type suspension is configured as described above, the center of the trunnion shaft and the drive shaft 200
Distance between center of trunnion shaft and driven shaft 30
By selecting a center-to-center distance of 0, the ratio of the load applied to both axes can be selected. Further, the drive shaft 200 and the driven shaft 300 make a circular motion with radii R ₁ and R ₂ , and the distance between the axes changes between D and D1.

The start assist device to which the present invention is applied is disposed above the drive shaft 200. The starting assist device, generally designated by the reference numeral 500, includes an air spring 505 and a mounting structure thereof. 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 piston member 520 is attached to the bracket 550 on the drive shaft side. Upper plate 530
Is attached to the bracket 560 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 mounting member 570 of a bracket on the frame side is fixed inside the frame. A bracket 560 whose lower side is open is provided integrally with the mounting member 570, and the 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 protrudes upward.

The air supply port 540 is connected to a compressed air supply source via an air supply pipe described later. Heavy vehicles are equipped with air compressors and high pressure tanks to assist clutches and brakes, and can use this compressed air supply. Air spring 505
When the compressed air is not supplied to the
0 and the driven shaft 300 are given an axial load at the same ratio as that of a normal trunnion type suspension. Air spring 505
When compressed air is supplied to the diaphragm 510, the diaphragm 510 expands and urges the drive shaft 200 toward the road surface. Due to this urging force, the contact pressure applied to the drive shaft tire 250 increases, and the propulsive force generated between the tire and the road surface also increases.

Therefore, when the vehicle which requires a large propulsion force starts, for example, by starting the start assist device, a smooth start can be achieved. The air spring, which is a component of the starting assistance device, is particularly susceptible to damage because the diaphragm is made of a flexible material. Therefore, the air spring is disposed inside the frame of the vehicle, and is further protected by covering with a bracket. In the trunnion type suspension, the housing rotates around the center line of the axle due to the vertical movement of the axle. Although this rotation causes a displacement between the upper support portion of the air spring and each support portion, the influence of this displacement can be minimized by disposing the air spring above the housing of the drive shaft.

In FIG. 7, the shaft load detecting device indicated generally by reference numeral 600 has a leaf spring 610 and a level sensor 650 for detecting the amount of displacement of the central portion of the leaf spring 610.

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

A front end of the leaf spring 610 is supported by a rear portion of the differential gear case 70 of the drive shaft 200 via a bracket 620. A rear end portion of the leaf spring 610 is supported by a front portion of the driven shaft casing 310 via a bracket 630. The bush 62 is provided between the bracket 620 and the leaf spring 610.
2 is provided to absorb the twist and the like of the bracket and the leaf spring. Similarly, the bracket 630 of the driven shaft supports the leaf spring via the bush.

The central portion of the leaf spring 610 is disposed vertically via mounting members 642 and 643,
The lower end of the forty is supported. The upper end of the rod 640 is connected to an arm 645 extending in the horizontal direction, and the arm 645 rotates the shaft 652 of the level sensor 650. The level sensor 650 is fixed to the chassis of the vehicle, and has a function of electrically detecting the rotation amount of the shaft 650.

Therefore, when the load applied to the drive shaft 200 and the driven shaft 300 changes, the suspension changes, and the vertical distance between the position of the rod mounting portion LC of the leaf spring and the position of the level sensor 650 changes. . Therefore, by electrically detecting the amount of change in this distance,
The shaft load applied to the drive shaft 200 and the driven shaft 300 can be detected. According to the type of suspension of the rear two-axle vehicle, there is a structure in which the distance D between the axles changes as the ground height of the axles 200 and 300 changes.

By applying the shaft load detection device to a suspension having this type of suspension, the detection sensitivity of the shaft load can be improved. That is, in a suspension in which the center distance D is increased as the product load increases with respect to the center distance D when the vehicle is empty, the mounting device LF at the front end of the leaf spring 610 and the mounting position LR at the rear end of the leaf spring 610. Is increased, the mounting position LC of the rod 640 rises, and the rod 640 is pushed upward. Rod 640
Is the displacement of the leaf spring 610 and the axis 200,
The sensor 650 is obtained by adding a displacement amount of 300 above the ground.
Is rotated, the rotation angle of the shaft 652 is increased, and the sensitivity is also improved.

FIG. 1 is an explanatory diagram showing an outline of a control device according to the present invention. The control device of the start-up assist device, generally denoted by reference numeral 800, has an air tank 810 and an air tank 81.
0 air is supplied to the first magnetic valve 820 (valve A), the second magnetic valve 830 (valve B), the piping 840, the first pressure switch 850 for detecting low pressure, and the second pressure for detecting high pressure. Pressure switch 8
It is sent to the air spring 505 of the start-up assist device 500 via 52 and increases the contact pressure of the drive shaft 200.

The control unit 860 includes an operation switch 872, an operation lamp 870, and a speed sensor 86.
8, a level sensor 650 which is an axle load sensor, a first pressure switch 850 for detecting low pressure, and a second pressure switch 850 for detecting high pressure.
The first magnetic valve 820 and the second magnetic valve 830 are connected to the pressure switch 852 of FIG.
Control. The first magnetic valve 820 supplies the air in the air tank 810 to the pipe 840 by opening the valve, and the second magnetic valve 830 has a function of exhausting the air in the pipe 840 by opening the valve. Have.

FIG. 2 shows the operation of the pressure detection switch.
The low pressure detection switch is a switch that detects whether the air in the air spring has been sufficiently discharged when air is discharged.
As shown in the figure, it is turned ON when the set pressure is aKg / cm ² or less.

The high pressure detection switch is a switch for detecting whether or not air is sufficiently supplied into the air spring when air is supplied, and is turned on when the set pressure is bKg / cm ² or more as shown in the figure. When the pressure is equal to or less than the set pressure a, the contact pressure of the tire of the drive shaft is equal to that of a vehicle not provided with the start assist device.
If the pressure is equal to or higher than the set pressure b, the contact pressure of the tire of the drive shaft increases, and the propulsive force at the time of starting also increases.

<< Operation of Start Auxiliary Device >> FIG. 3 is a flowchart showing a control process of the control device 800 of the present invention. In step S10, the main switch is turned on, and in step S11, the state of the switch 872 for selecting the mode for increasing the axle load of the rear drive wheel by the start assist device and the state of the level sensor 650 for detecting the presence or absence of loading are checked. If the axle load increasing mode (the operation switch is on and the empty state is set), the valve 82 is set in step S20.
0 is opened, and air is supplied to the air spring 505 of the start assist device 500 until the high pressure switch 852 becomes equal to or higher than the set pressure.

In step S21, the running state of the vehicle is checked. If the vehicle is stopped, it is confirmed in step S22 that the high-pressure switch is higher than the set pressure. If the air pressure is insufficient, the air is supplied to the air spring by opening the valve 820 for the time set in step S23 (for example, for one second).

In step S24, while the axle load increasing mode is continued, the operation from step S21 is repeated. If the operation switch is turned off or loaded, step S
Proceeding to 30, the air is supplied to the air spring 505 until the low pressure switch 850 becomes higher than the set pressure.

If a stop is detected in step S31, the low pressure switch 850 checks in step S32 whether the pressure is equal to or higher than the set pressure. If the air pressure is insufficient, the flow proceeds to step S32.
At 33, air is supplied for a set time.

In step S34, it is checked whether the mode is the axle load increasing mode. If the mode is not the axle load increasing mode, the flow returns to step S31 to repeat the above-described operation. If the mode has been switched to the axle load increasing mode, the high pressure switch 85 is set in step S35.
Until the pressure becomes equal to or higher than the set pressure, air is supplied to the air spring, and the process proceeds to step S21.

[0032]

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 operate the air spring when the vehicle starts moving to reduce the ground pressure. In a vehicle equipped with a start-up assist device for increasing, based on the operation mode of the start-up assist device, air that maintains the mode is supplied to the air spring, and only when the air is insufficient, the valve is opened for a short time and the air is opened. Is to supply. Therefore, the consumption of air is small and an economical device can be constructed.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram showing the operation of a pressure detection switch.

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

FIG. 4 is a plan view of a vehicle equipped with a start assist device.

FIG. 5 is a side view of FIG. 4;

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

FIG. 7 is an explanatory diagram of a shaft load detecting device.

FIG. 8 is an explanatory diagram of a level sensor.

FIG. 9 is an explanatory view showing an outline of a vehicle having two rear axles.

[Explanation of symbols]

 DESCRIPTION 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 Start assist 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 650 Shaft load detecting device (level sensor) 800 Control device 810 Air tank 820 First valve 830 Second valve 860 CPU 866 Parking brake switch 8 8 speed sensor 872 operated switch

Claims (1)

[Claims] The vehicle has two rear axles, one of which is used as a drive shaft, the other axle is used as a driven shaft, and is mounted on the drive shaft to increase the contact pressure of tires of the axle. A vehicle provided with a start-up assist device having an air spring, a vehicle speed sensor for detecting a vehicle speed, a level sensor for detecting a load on an axle, an air supply source for supplying compressed air to the air spring, and provided in an air pipe. A first valve for supplying air to the air spring, a second valve for exhausting air from the air spring, a pressure sensor for detecting an internal pressure of the air spring, and an internal pressure of the air spring when the start assist device is activated. And a control unit that opens the second valve until the internal pressure of the air spring becomes a second predetermined value smaller than the first predetermined value when the start assist device is not operated. Equipment The control unit, when stopped and when the start assist device is operated and the internal pressure of the air spring is equal to or less than a first predetermined value, or when stopped and when the start assist device is not operated and the internal pressure of the air spring is the second predetermined value, A vehicle provided with a start-up assist device that opens a first valve for a predetermined time when: