JP2003026051A - Car height adjusting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively constitute a device for economizing air pressure consumed for adjusting the car height by an air spring for supporting a cab by a chassis frame. SOLUTION: Going in and out of the air pressure to the air spring at traveling time is prohibited by using an electric signal for indicating that a vehicle is in traveling, for example, an operating signal of a parking brake. This constitution can inexpensively constitute the device by using a solenoid valve and its control unit for prohibiting going in and out of the air pressure to the air spring when tilting the cab as the solenoid valve and its control unit for prohibiting going in and out of this air pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a vehicle height adjusting device for supporting a cab of a large automobile on a chassis frame via an air spring. The present invention relates to an improvement for reducing consumption of air pressure supplied to an air spring.

[0002]

2. Description of the Related Art In order to improve the riding comfort of a cab operated by a driver, an air spring is provided between a cab of a large vehicle and a chassis frame, and a device for automatically adjusting the air pressure by a leveling valve has become popular. ing. Since large vehicles are often used for long-distance operations,
Such a device has been well received as a device for reducing driver fatigue.

In this device, when performing a cab tilt for the maintenance of an internal combustion engine or the like, it is necessary to block the entry and exit of air pressure to and from the air spring. For this reason, it is known that an electromagnetic valve that automatically prohibits the air pressure to the air spring is provided in association with the tilt operation.

[0004]

When the air pressure of the air spring provided between the cab and the chassis frame is continuously adjusted by the leveling valve, the vehicle is accelerated or decelerated depending on the road surface condition while the vehicle is running. Since the air pressure is adjusted each time, the air pressure consumption from the pneumatic tank increases. For large-sized freight vehicles used for long-distance travel, it is extremely important to reduce fuel consumption per mileage as much as possible to save operating costs of the vehicle. Air pressure consumption due to frequent operation of the leveling valve is extremely important. , The operation time of the compressor is lengthened to affect the overall fuel consumption.

Between the lower limit value and the upper limit value of the leveling valve, there is a dead zone where air pressure does not flow in and out.
In order to remedy this, we tried to reduce the consumption of air pressure by increasing the width of this dead zone. However, if such a setting is made, the vehicle height initial value of the cab, that is, the suspension stroke will vary, and a stable ride comfort cannot be obtained, and the driver who uses the vehicle will have doubts. The initial value of the vehicle height of the cab must be properly controlled according to the weight of the cab before the vehicle starts traveling, that is, the weight of the occupant and the load in the cab.

As a conventional technique for improving this, the vehicle height average value within a predetermined time is detected, and the air pressure control is performed by controlling the inflow / outflow of the air pressure to / from the air spring so as to maintain the vehicle height average value appropriately. A technique for reducing the number of times and reducing the consumption of air pressure is disclosed in Japanese Patent Application Laid-Open No. 8-108731. Also, at times when the cab vibrates, such as when the vehicle is in a starting state or in a braking state, the program control circuit operates to prevent the air pressure from entering and leaving the air spring, thereby controlling the number of times of air pressure control. A technique for reducing the number is disclosed in Japanese Patent Laid-Open No. 8-301142. However, the above-mentioned two conventional techniques have the drawbacks that the control is high-grade and complicated, and the control of the air spring supporting the cab is too expensive.

The present invention has been made against such a background, and an object thereof is to reduce consumption of air pressure by an air spring supporting a cab on a chassis frame with a simple and economical device. An object of the present invention is to reduce the running fuel consumption of a vehicle. The present invention is
An object of the present invention is to reduce the frequency of air pressure adjustment of the air spring without impairing the riding comfort in the cab.

[0008]

SUMMARY OF THE INVENTION The present invention adjusts the air pressure of an air spring that supports a cab when the vehicle is less swaying before the vehicle starts running, and supports the cab after the vehicle starts running. Its main feature is that it is configured to prohibit the entry and exit of air pressure from the air spring.
The present invention prohibits the entry and exit of air pressure to and from the air spring by a simple electric signal indicating that the vehicle is traveling, and its configuration is extremely simple and inexpensive. Moreover, for that prohibition control, by using the existing solenoid valve and its control unit that prohibits the entry and exit of air pressure to the air spring when the cab is tilted,
The number of additional members can be extremely reduced and the cost can be reduced.

That is, according to the present invention, the air springs (3, 4) arranged between the cab (1) and the chassis frame (2) and the distance between the cab and the chassis frame are maintained within a certain range. In the vehicle height adjusting device having the leveling valves (5, 6) for adjusting the air pressure of the air spring, the inflow and outflow of air pressure to and from the leveling valve according to an electric signal indicating that the vehicle is traveling. Is provided with a solenoid valve (7, 8) for prohibiting.

The numbers in the above parentheses are the reference numbers in the drawings of the embodiments described later. This is added to facilitate understanding of the configuration of the present invention, and is not intended to limit the configuration of the present invention to the examples. The same applies to the following description.

In the configuration of the present invention, the vehicle height adjustment of the cab is performed before the vehicle starts. If the vehicle height of the cab is adjusted just before the vehicle is started, if the weight of the person in the cab and the weight of the items loaded in the cab are used, the air pressure of the air spring will be adjusted after the vehicle starts. Even without it, the ride is comfortable enough. In the configuration of the present invention, the operation is performed after the driver inserts the engine key to start the engine and before the vehicle starts. Since the vehicle height adjustment operation is not performed while the vehicle is traveling, the air pressure will not be lost due to shaking or vibration during traveling. The vehicle height adjustment is performed again after the vehicle is stopped until the driver turns off the engine key, but this period is generally short and does not pose a problem regarding exhaustion of air pressure.

The electric signal indicating that the vehicle is traveling may be either traveling when it is in the "on" state or traveling when it is in the "off" state. The simplest electrical signal is the parking brake actuation signal. It suffices to say that the vehicle is traveling when the parking brake is released, and is not traveling when the parking brake is applied. In addition to this, a signal indicating that the transmission is in a position other than the neutral position or a signal indicating that the vehicle speed is present can be used as an electric signal for this purpose. It is also possible to design the logic circuit such that it is running by a combination of these signals, ie by any of these signals, or when there are two or three signals at the same time.

All of these electric signals are existing signals in the design of large vehicles, and it is not necessary to design a circuit for extracting the signals again. Further, in the present invention, the air spring is controlled, and it is not a device for directly performing control for traveling. Therefore, there is no problem even if there is some deviation between the signal and the actual traveling state. For example, there is no problem even if some time elapses after the parking brake is released until the vehicle actually starts.
It does not matter if the shift lever is put into the starting gear from the neutral position and some time elapses before the vehicle actually starts. The vehicle may be temporarily stopped while waiting for a signal while traveling on the road. During such a temporary stop, the vehicle height may or may not be adjusted. If you want to adjust the vehicle height during a temporary stop,
It is preferable to use a signal indicating that there is a vehicle speed from the speed information.
In this case, it is not always necessary to set the vehicle speed to a value other than "zero", and it is possible to set the vehicle speed to be set when the vehicle speed is slightly high, for example, when the vehicle speed exceeds several kilometers per hour.

In a design with an existing solenoid valve that inhibits the inflow and outflow of air pressure into the leveling valve when tilting the cab, the inhibit solenoid valve (7, 8) utilizes this. It is the most economical to do. In other words, the cab can be tilted when the engine is inspected or when necessary.In a device with a structure in which the cab is supported by an air spring, the cab works in conjunction with the tilt operation to prevent air pressure from entering and exiting the air spring during tilting. A solenoid valve is provided to shut off the pneumatic circuit to the air spring. If this solenoid valve is used to prevent the air pressure from flowing in and out of the air spring while the vehicle is traveling, the present invention does not require any additional components such as a solenoid valve, which is extremely economical. Also, a control unit for controlling the tilt solenoid valve can be used in the present invention. As a result, the number of parts and design changes to be added can be extremely reduced.

The logic circuit for changing the state of the solenoid valve before and after the vehicle travels is extremely simple and can be constructed by a simple relay circuit or semiconductor circuit. Therefore, it is not necessary to newly provide a program control circuit for this purpose. Even when the program control circuit is used, its logical operation is extremely small. Therefore, it can be easily realized by incorporating such a logic in a part of some existing control circuit.

The configuration of the present invention does not impair the riding comfort of the cab. For example, if the vehicle height adjustment is performed before the parking brake is released, the riding comfort is not effectively changed even if the vehicle height adjustment is not performed after the parking brake is released. When the driver wants to adjust the vehicle height for some reason, the vehicle height adjustment will be linked and executed by temporarily operating the parking brake at a stop waiting for a signal, etc. There is no inconvenience above.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment will be described with reference to the drawings.
FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention. Figure 2
FIG. 3 is a perspective view of a leveling valve with a solenoid valve. In this device, air springs 3 and 4 are provided between a cab 1 provided with a driver's seat and a chassis frame 2. The air spring 3 is the front air spring,
Although not shown in the figure, one is provided on each of the left and right sides. The air spring 4 is a rear air spring, and one air spring is provided on each of the left and right sides.

Leveling valves 5 and 6 are connected to the air passages of the air springs 3 and 4, respectively. When the leveling valve 5 or 6 detects that the vehicle height is low, the pneumatic tank 10 responds. When the leveling valve 5 or 6 detects that the vehicle height is high, the air pressure of the air spring 3 or 4 is discharged to the atmosphere. This is a well known mechanical device.

In the apparatus of the embodiment of the present invention, a leveling valve with an electromagnetic valve is used as the leveling valve 5 (and 4). FIG. 2 is a perspective view illustrating the structure.
The pneumatic tank 10 is connected to the inlet 11 of the leveling valve 5 via a pipe line. Pneumatic tank 10
Is an air pressure tank for brake pressure of this vehicle, and is constructed so that air pressure in a constant pressure range is always maintained in the air pressure tank 10 in association with the rotation of the engine.

The air spring 3 is connected to the outlet 12 of the leveling valve 5 via a flexible conduit. This leveling valve 5 is attached to the cab side, and its arm 13 is attached to the chassis frame 2 via a rod 14. Therefore, when the air pressure of the air spring 3 increases, the air spring 3 expands and the vehicle height increases, so that the arm 13 is pushed downward by the rod 14, and the air pressure of the air spring 3 is released from the exhaust port 15 into the atmosphere. . When the air spring 3 contracts and the vehicle height decreases, the arm 13 is pushed upward, and the air pressure of the inlet 11 flows into the air spring 3.

An electromagnetic valve 7 is fixedly provided on the leveling valve 5 of this embodiment. Terminal 16
When the solenoid valve 7 is activated by the control current supplied from the air spring 3 regardless of the position of the arm 13.
It is configured to prohibit the entry and exit of air pressure to and from.
A control current is supplied to the terminal 16 from the control unit 20 as shown in FIG. The control unit 20 is arranged to continuously supply this control current when the vehicle is traveling. In this example, the operation signal PB of the parking brake is used, and its logic circuit is configured to supply a control current to the terminal 16 when the parking brake is released.

Further, in the apparatus of the embodiment of the present invention, the leveling valve 5 with the solenoid valve is an apparatus of an existing design which is operated when performing a cab tilt. Also this solenoid valve 7
The control unit 20 that supplies a control current to the control valve 20 is an existing control unit that also supplies a control current to the solenoid valve 7 when performing a cab tilt, and the present invention is based on a slight modification of the control unit 20. It can be carried out. With such a design change, the present invention can be implemented without changing or adding the solenoid valve 7 (or 8).

Instead of the parking brake operation signal PB or together with the parking brake operation signal PB, a neutral signal N and / or a vehicle speed signal V of the transmission are taken in and controlled at a terminal 16 when the vehicle is in a traveling state. The logic to deliver the current can be configured.

With such a structure, the leveling valve 5 or 6 does not frequently operate due to shaking or vibration while the vehicle is running, and the air pressure in the pneumatic tank 10 is not consumed. Therefore, the power required to supply the air pressure to the air pressure tank 10 is correspondingly reduced, and the fuel consumption of the engine is reduced accordingly.

[0025]

According to the present invention, it is possible to reduce the consumption of air pressure of the air spring that supports the cab on the chassis frame without impairing the riding comfort in the cab.
As a result, the traveling fuel consumption of the vehicle can be reduced. The configuration of the present invention is simple and economical. Especially,
By utilizing the solenoid valve for the cab tilt and its control unit, the invention can be economically implemented with a minimum of additional parts.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of an apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view of a leveling valve with a solenoid valve.

[Explanation of symbols]

1 cab 2 chassis frame 3 Air spring (front) 4 Air spring (rear) 5 Leveling valve (front) 6 Leveling valve (rear) 7 Solenoid valve (front) 8 Solenoid valve (rear) 10 Pneumatic tank 11 inlets 12 outlets 13 arms 14 rod 15 exhaust port 16 terminals 20 control unit

Claims (3)

[Claims] 1. An air spring disposed between a cab and a chassis frame, and a leveling valve for adjusting an air pressure of the air spring so that a distance between the cab and the chassis frame is maintained within a certain range. A vehicle height adjusting device provided with a solenoid valve for prohibiting inflow and outflow of air pressure to and from the leveling valve in response to an electric signal indicating that the vehicle is traveling. 2. The electric signal is any one of a signal indicating that the parking brake is in a released state, a signal indicating that the transmission is in a position other than the neutral position, and a signal indicating that the vehicle speed sensor indicates that the vehicle speed is present. The vehicle height adjusting device according to claim 1, which is one or a combination thereof. 3. The vehicle height adjusting device according to claim 1, wherein the prohibiting means uses a solenoid valve that prohibits inflow and outflow of air pressure into the leveling valve when the cab is tilted.