JP2015217844A - Vehicle height adjust system control apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To disengage minimum pressure hold control on an as required basis.SOLUTION: A control apparatus for a vehicle height adjust system 10 that can adjust a vehicular height at a target vehicular height by supplying and exhausting air relative to air springs 14L, 14R includes: a vehicle height adjustment control part 41 for adjusting a vehicular height at a target vehicular height by executing ascent control to increase a vehicular height by supplying the air springs 14L, 14R with air, or descent control to decrease the vehicular height by exhausting the air from the air springs 14L, 14R; a minimum-pressure hold control part 42 for holding internal pressure of the air springs 14L, 14R at minimum pressure when the internal pressure thereof decreases to given minimum pressure when the descend control is performed; and a minimum pressure hold disengagement part 44 for disengaging a minimum pressure hold when a vehicular height decrease amount is less than a given value when the descent control is performed, or a load exerted to the air springs 14L, 14R is less than a given value.

Description

  The present invention relates to a control device for a vehicle height adjustment system, and more particularly to a control device for a vehicle height adjustment system that can adjust a vehicle height to a target vehicle height by supplying and discharging air to and from an air spring.

  Conventionally, large vehicles such as trucks are equipped with a vehicle height adjustment system that adjusts the vehicle height to a desired target vehicle height by controlling the air supply and discharge to the air spring provided between the axle and the frame. Those are known (for example, see Patent Documents 1 and 2).

JP 62-218212 A JP 2008-030701 A

  As shown in FIG. 5, an air spring 100 of a general vehicle height adjustment system includes a cylindrical air bellows 110, a piston 120 that is fitted into the air bellows 110 and fixed to the axle (not shown) side, And an upper lid 130 provided on the top of the air bellows 110 and fixed to the frame (not shown) side. Such a vehicle height adjustment system is known to have a minimum pressure holding control for holding the internal pressure of the air spring 100 at a predetermined minimum pressure in order to prevent the air bellows 110 from being detached from the upper lid 130 or the piston 120. It has been.

  However, if the descent control is performed to lower the vehicle height to the target vehicle height with the sprung weight being low, the descent of the vehicle height is hindered by the friction of the suspension or the like, and the air in the air spring 100 escapes more than necessary. There is. For this reason, there is a possibility that the vehicle height cannot be lowered to the target vehicle height because the air spring internal pressure reaches the minimum pressure before the vehicle height drops to the target vehicle height.

  An object of the present invention is to effectively prevent the vehicle height from being lowered to a desired target vehicle height by appropriately releasing the minimum pressure holding control as necessary.

  In order to achieve the above object, the present invention provides a control device for a vehicle height adjustment system capable of adjusting a vehicle height to a target vehicle height by supplying / discharging air to / from an air spring, and supplying air to the air spring. Vehicle height adjustment control means for adjusting the vehicle height to the target vehicle height by executing a rise control for raising the vehicle height or a drop control for discharging the air from the air spring to lower the vehicle height, When the internal pressure of the air spring decreases to a predetermined minimum pressure, the minimum pressure holding means for holding the internal pressure of the air spring at the minimum pressure, and the vehicle height drop amount during the descent control is less than a predetermined value, or the air And a minimum pressure holding releasing means for releasing the minimum pressure holding by the minimum pressure holding means when the load applied to the spring is less than a predetermined value.

  In addition, when adjusting the vehicle height to the target vehicle height in a state where the minimum pressure holding is released, the vehicle height adjustment control means executes a descent control for lowering the vehicle height below the target vehicle height, It is preferable to execute ascent control for raising the height to the target vehicle height.

  According to the control device for a vehicle height adjustment system of the present invention, it is possible to effectively prevent the vehicle height from being lowered to a desired target vehicle height by appropriately releasing the minimum pressure holding control as necessary. it can.

1 is a schematic overall configuration diagram showing a vehicle equipped with a vehicle height adjustment system according to an embodiment of the present invention. It is a functional block diagram which shows the electronic control unit (ECU) which concerns on one Embodiment of this invention. In one Embodiment of this invention, it is a figure explaining an example of vehicle height adjustment at the time of canceling | releasing minimum pressure holding | maintenance control. It is a flowchart explaining the control content which concerns on one Embodiment of this invention. It is a typical perspective view which shows the air spring used for a general vehicle height adjustment system.

  Hereinafter, based on an accompanying drawing, a control device of a vehicle height adjustment system concerning one embodiment of the present invention is explained. The same parts are denoted by the same reference numerals, and their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  As shown in FIG. 1, a vehicle height adjustment system 10 according to this embodiment is mounted on a towing vehicle such as a tractor, for example, and includes an air tank 11, an air pipe 12, a pair of left and right air valves 13L and 13R, A left air spring 14L provided corresponding to the rear wheel 20L, a right air spring 14R provided corresponding to the right rear wheel 20R, and an electronic control unit (hereinafter referred to as ECU) 40 are provided. In FIG. 1, reference numerals 21L and 21R indicate left and right steering wheels (front wheels), and reference numerals 22L and 22R indicate left and right small lights, respectively.

  The air tank 11 stores compressed air supplied from a compressor (not shown) mounted on the vehicle 1. The air tank 11 is connected to an upstream end of an air pipe 12.

  The air pipe 12 is branched at the downstream side by a substantially T-shaped pipe joint 12A. A left air valve 13L is interposed in the air pipe 12 on the left downstream side of the pipe joint 12A, and a left air spring 14L is connected to the downstream end thereof. A right air valve 13R is interposed in the air pipe 12 on the right downstream side of the pipe joint 12A, and a right air spring 14R is connected to the downstream end thereof.

  The left air valve 13L opens and closes in response to an operation instruction signal from the ECU 40, thereby supplying air to the left air spring 14L or discharging air from the left air spring 14L. The right air valve 13R opens and closes in response to an operation instruction signal from the ECU 40, thereby supplying air to the right air spring 14R or discharging air from the right air spring 14R.

  Both the left air spring 14L and the right air spring 14R are interposed between a drive shaft and a frame (not shown) of the vehicle 1. These left and right air springs 14L and 14R function as actuators that move the vehicle height up and down by expanding and contracting in the vertical direction of the vehicle body according to the supply and discharge of air.

  The left internal pressure sensor 15L is provided in the air pipe 12 on the downstream side of the left air valve 13L, and detects the internal pressure of the left air spring 14L. The right internal pressure sensor 15R is provided in the air pipe 12 on the downstream side of the right air valve 13R, and detects the internal pressure of the right air spring 14R. The left vehicle height sensor 16L detects the left vehicle height of the vehicle 1 from the amount of displacement of the left air spring 14L. The right vehicle height sensor 16R detects the right vehicle height of the vehicle 1 from the amount of displacement of the right air spring 14R. The sensor values of these various sensors are transmitted to the electrically connected ECU 40.

  The ECU 40 performs various controls of the vehicle 1, and includes a known CPU, ROM, RAM, input port, output port, and the like. Further, as shown in FIG. 2, the ECU 40 includes a vehicle height adjustment control unit 41, a minimum pressure hold control unit 42, a vehicle height descent malfunction determination unit 43, a minimum pressure hold release unit 44, and a vehicle travel prohibition unit 45. As a part of functional elements. In the present embodiment, these functional elements are described as being included in the ECU 40, which is an integral piece of hardware. However, any one of these functional elements may be provided in separate hardware.

  The vehicle height adjustment control unit 41 opens and closes the air valves 13L and 13R and supplies air to the air springs 14L and 14R so that the current vehicle height input from the vehicle height sensors 16L and 16R becomes a predetermined target vehicle height. Car height adjustment control is performed to control exhaust. Hereinafter, the vehicle height adjustment that raises the vehicle height by supplying air to the air springs 14L and 14R is referred to as “lift control”, and the vehicle height adjustment that discharges air from the air springs 14L and 14R to lower the vehicle height. It is called “descent control”.

  The minimum pressure holding control unit 42 executes minimum pressure holding control for holding the internal pressures of the air springs 14L and 14R at a predetermined minimum pressure during the descent control. More specifically, when the internal pressure detected by the internal pressure sensors 15L and 15R is lowered to a predetermined minimum pressure by the drop control, the minimum pressure holding control unit 42 sends a valve closing instruction signal to the air valves 13L and 13R to stop the drop control. Send. As a result, it is possible to effectively avoid that the internal pressure of the air springs 14L, 14R is lower than the minimum pressure, and damage of the air springs 14L, 14R can be prevented.

  The vehicle height descent malfunction determination unit 43 determines that the vehicle height descent is abnormal when the amount of vehicle height descent input from the vehicle height sensors 16L and 16R during the descent control is less than a predetermined value. This is because even if air is discharged from the air springs 14L and 14R, it is considered that the vehicle height drop is hindered by friction such as suspension. In addition, you may determine the malfunction of vehicle height fall based on whether the sprung weight with respect to the air springs 14L and 14R is less than a predetermined value. Similarly, when the sprung weight is light, there is a high possibility that the vehicle height drop is hindered by friction such as suspension. The sprung weight for the air springs 14L, 14R may be estimated based on the pressure input from the internal pressure sensors 15L, 15R.

  The lowest pressure holding release unit 44 releases the lowest pressure holding by the lowest pressure holding control unit 42 when the vehicle 1 is stopped and the vehicle height drop is determined to be unsatisfactory. This is because when the vehicle height drop is not satisfactory, air in the air springs 14L and 14R may escape more than necessary before the vehicle height drops to the target vehicle height. The reason for stopping the vehicle 1 is that the air bellows is unlikely to come off from the upper lid or the piston even if the internal pressures of the air springs 14L and 14R are reduced below the minimum pressure.

  The vehicle travel prohibition unit 45 prohibits the travel of the vehicle 1 until the vehicle height is adjusted to the target vehicle height when the minimum pressure holding is released. Thereby, it is possible to reliably prevent the vehicle 1 from traveling in a state where the internal pressures of the air springs 14L and 14R are lower than the minimum pressure.

  Here, an example of vehicle height adjustment by the vehicle height adjustment control unit 41 when the minimum pressure holding is released will be described with reference to FIG.

  As shown in FIG. 3A, descent control for discharging air from the air springs 14L and 14R is started from a state where the current vehicle height (solid line) is higher than the target vehicle height (broken line) while the vehicle 1 is stopped. To do. This descent control is continued until the vehicle height becomes lower than the target vehicle height, as shown in FIG. Thereafter, when the vehicle height becomes lower than the target vehicle height, as shown in FIG. 3C, ascent control for increasing the vehicle height to the target vehicle height is executed. Thus, by performing the ascending control after the descending control, it becomes possible to reliably adjust the vehicle height to the target vehicle height even in a state where the friction due to the suspension or the like is large.

  Next, a control flow by the control device of the vehicle height adjustment system according to the present embodiment will be described based on FIG.

  In step S100, the minimum pressure holding control is activated (ON), and in step S110, it is determined whether or not the current vehicle height detected by the vehicle height sensors 16L and 16R is higher than the target vehicle height. If the current vehicle height is higher than the target vehicle height (Yes), the process proceeds to step S120. On the other hand, if the current vehicle height is less than or equal to the target vehicle height (No), the process proceeds to step S190. If the current vehicle height is not the target vehicle height in step S190 (Yes), the process proceeds to step S200, where the vehicle height adjustment to the target vehicle height is performed by normal ascent control, and in step S190, the current vehicle height is changed to the target vehicle height. In the case of, return is performed without performing any ascent / descent control.

  In step S120, the descent control is executed for a predetermined period (for example, several seconds), and in step S130, it is determined whether or not the vehicle height drop is malfunctioning based on the vehicle height drop amount. If the vehicle height drop is unsatisfactory (Yes), the process proceeds to step S140. On the other hand, if the vehicle height drop is not abnormal (No), the process proceeds to step S210, and the vehicle height adjustment to the target vehicle height by the normal drop control is executed. Note that step S120 may be omitted when it is determined based on the sprung weight that the vehicle height drop is not good.

  In step S140, the minimum pressure holding control is released (OFF) and the vehicle 1 is prohibited from traveling. Further, in step S150, the lowering control for lowering the vehicle height from the target vehicle height is executed, and in step S160, the raising control for increasing the vehicle height to the target vehicle height is executed. Thereafter, in step S170, the travel prohibition of the vehicle 1 is canceled and the present control is returned.

  Next, the effect by the control apparatus of the vehicle height adjustment system which concerns on this embodiment is demonstrated.

  If the descent control is performed in a state where the sprung weight with respect to the air springs 14L and 14R is low, the descent of the vehicle height is hindered by the friction of the suspension or the like, and air in the air springs 14L and 14R may escape more than necessary. is there. When the minimum pressure holding control is operated in such a state, there is a problem that the vehicle height cannot be lowered to the target vehicle height.

  According to the control device of the present embodiment, when the vehicle height drop amount during the descent control is very small, or when the sprung weight with respect to the air springs 14L, 14R is low, the minimum pressure holding is released, so the vehicle height drop Can be reliably prevented from stopping in a state where the vehicle does not fall down to the target vehicle height. In addition, when the minimum pressure holding is released, the vehicle height is made lower than the target vehicle height by lowering control, and then the vehicle height is adjusted to the target vehicle height by raising control that is not affected by friction or the like. . Therefore, it is possible to accurately adjust the vehicle height to the target vehicle height as compared with the case where the vehicle height is adjusted only by the descent control.

  In addition, this invention is not limited to the above-mentioned embodiment, In the range which does not deviate from the meaning of this invention, it can change suitably and can implement.

  For example, although it has been described that the malfunction of the vehicle height descent is determined by the vehicle height descent amount or the sprung weight during descent control, whether or not the towing side king pin is engaged with the towing side vehicle 1 coupler. You may determine based on. Further, the vehicle 1 is not limited to a tractor, and can be widely applied to vehicles on which the vehicle height adjustment system 1 can be mounted, such as a van body type or a flat body type truck.

1 Vehicle 10 Vehicle Height Adjustment System 14L Left Air Spring 14R Right Air Spring 40 ECU
41 Vehicle height adjustment control unit 42 Minimum pressure retention control unit 43 Vehicle height drop malfunction determination unit 44 Minimum pressure retention release unit 45 Vehicle travel prohibition unit

Claims (2)

A control device for a vehicle height adjustment system capable of adjusting a vehicle height to a target vehicle height by supplying and discharging air to an air spring,
Vehicle height adjustment that adjusts the vehicle height to the target vehicle height by executing the ascending control to raise the vehicle height by supplying air to the air spring or the descending control to discharge the air from the air spring and lower the vehicle height Control means;
When the internal pressure of the air spring decreases to a predetermined minimum pressure during the descent control, minimum pressure holding means for holding the internal pressure of the air spring at the minimum pressure;
A minimum pressure holding release means for releasing the lowest pressure holding by the lowest pressure holding means when the vehicle height drop amount during the lowering control is less than a predetermined value, or when the load applied to the air spring is less than a predetermined value; A vehicle height adjustment system control device comprising: The vehicle height adjustment control means includes:
When adjusting the vehicle height to the target vehicle height when the minimum pressure is not released, after performing the lowering control to lower the vehicle height below the target vehicle height, the ascent control to raise the vehicle height to the target vehicle height. The vehicle height adjustment system control device according to claim 1.

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