JPH04331621A - Suspension device for vehicle - Google Patents

Abstract

PURPOSE:To prevent the inner wheel side from being floated at the time of the limit roll when a vehicle is turned by effectively utilizing the lateral acceleration generated when the vehicle is turned. CONSTITUTION:In a suspension device for a vehicle having pressure control valves 21, 31, 41, 51 controlling the pressures applied to suspension cylinders 23, 33, 43, 53 respectively constituted of a main valve and pilot valves 21b, 31b, 41b, 51b, the pilot valves 21b, 31b, 41b, 51b are arranged so that plungers 118 of the pressure control valves 21, 41 or 31, 51 controlling the pressures to the suspension cylinders 23, 43 or 33, 53 arranged between the wheels located on the inside when the vehicle is turned and a vehicle body are located on the outside of valve bodies 115.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a suspension system for a vehicle, and more particularly to a pump that discharges hydraulic fluid sucked from a reservoir into a high-pressure passage, and a suspension cylinder that is disposed between each wheel and a vehicle body and expands and contracts. and a pressure control valve that respectively controls the pressure applied from the high pressure passage to each of these suspension cylinders, and each of the pressure control valves is connected to a line pressure port communicating with the high pressure passage and the reservoir. A low pressure port communicating with the return passage, an output port communicating with the supply/discharge passage connected to the suspension cylinder, a pilot chamber connected to the high pressure passage via an orifice, and one end receiving the pressure of the output port to generate this pressure. is driven in the direction of lowering the degree of communication between the line pressure port and the output port and increasing the degree of communication between the low pressure port and the output port, and receives the pressure of the pilot chamber at the other end, and this pressure causes the line to a main valve having a spool that is driven in a direction that increases the degree of flow between the pressure port and the output port and lowers the degree of flow between the low pressure port and the output port; an inlet port that communicates with the pilot chamber; An outflow port that communicates with the connected return passage, a valve body that regulates the degree of flow between these two ports by axial movement, and a valve body that is coaxially provided on the back of this valve body and that adjusts the flow rate depending on the current value. The present invention relates to a suspension device for a vehicle that includes a pilot valve equipped with an electromagnetic drive means having a plunger that is driven in a direction that lowers the degree of permeability.

0002

[Prior Art] This type of vehicle suspension device is
For example, it has been proposed in Japanese Patent Application Laid-Open No. 2-225119. However, in the vehicle suspension system proposed in the same publication, no consideration is given to the arrangement of pilot valves in each pressure control valve that controls the pressure to each suspension cylinder arranged between each wheel and the vehicle body. It has not been.

0003

[Problems to be Solved by the Invention] By the way, the relationship (current-pressure characteristic) between the value of current applied to the pilot valve in each pressure control valve and the pressure (control pressure) applied to each suspension cylinder is shown in A of FIG. It looks like this,
In a low current region of the control range, the pressure outputted relative to the command current value becomes higher away from the data line Lo of the control map stored in the computer that controls the operation of the pressure control valve. This causes a problem in that the inner wheel side lifts up when the vehicle turns at its limit roll. One way to solve this problem is to change the computer's control map, but this creates new problems such as complicated logic and uneven transitions. An object of the present invention is to effectively utilize the lateral acceleration generated when the vehicle turns to prevent the inner wheels from lifting up at the limit roll of the vehicle turn.

0004

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention provides a suspension system for a vehicle of the above-described type, in which a suspension cylinder is provided between a wheel that becomes inside when the vehicle turns and the vehicle body. The pilot valve was arranged so that the plunger of the pressure control valve, which controls the pressure on the valve, was located outside the valve body.

[0005]

[Operations and Effects of the Invention] In the vehicle suspension system according to the present invention, the pilot valve plunger in each pressure control valve that controls the pressure to each suspension cylinder disposed between the inner wheel and the vehicle body when the vehicle turns The valve body receives an outward acting force (centrifugal force) due to lateral acceleration generated when the vehicle turns. By the way, this acting force acts in the direction of increasing the degree of communication between both ports of each pilot valve, so the current-pressure characteristic of each pressure control valve becomes as shown in B in Fig. 4, and the entire control range is is approximated to the data line Lo of the control map stored in the computer. Therefore, it is possible to accurately control the pressure applied to each suspension cylinder, and it is possible to accurately prevent the inner wheel from lifting up when the vehicle turns at its limit roll. By the way, the present invention can be implemented by changing the layout of each pilot valve, and there are no secondary problems that occur when changing a computer control map, and it is economical and performance efficient. is also extremely good.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a hydraulic circuit of a vehicle suspension device according to the present invention, in which a pump 12 is connected to a reservoir 11, and a pump 12 is connected to a reservoir 11.
The hydraulic fluid sucked from 1 is attenuator 13
and is configured to be discharged into the high pressure passage P1 via the check valve 14, and the line pressure within the high pressure passage P1 is detected by the line pressure detection sensor 15. The pump 12 is driven by the engine (not shown) of the vehicle, and the maximum discharge pressure from the pump 12 is regulated by a relief valve 16 to prevent abnormal pressure rise.

Further, the high pressure passage P1 is provided with a front wheel accumulator 17 and a rear wheel accumulator 18.
Each pressure control valve 21, 31, 41, 51 and each cut valve 22
, 32, 42, 52, each suspension cylinder (hydropneumatic cylinder arranged between each wheel and the vehicle body) 23, 33, 43, 53 is connected,
The hydraulic pressure applied to each suspension cylinder 23, 33, 43, 53 is configured to be detected by each pressure sensor 24, 34, 44, 54. In addition, each pressure control valve 21, 31, 41, 51 and each cut valve 22, 32
, 42, 52 are provided with relief valves 25, 35, 45, 55.
are provided, and each suspension cylinder 23, 3
Abnormal pressure increase in the internal pressure of 3, 43, and 53 is prevented.

Each pressure control valve 21, 31, 41, 51 is
Supply/discharge passage P2 and high pressure passage P1 or reservoir 11 connected to each suspension cylinder 23, 33, 43, 53
Each suspension cylinder 23, 33,
43, 53, and the main valves 21a, 31a, 41a, which control a large flow of hydraulic fluid.
51a, and electromagnetic pilot valves 21b, 31b, 41b, and 51b that control the operation of the main valve by controlling a small flow of hydraulic fluid. Each cut valve 22, 32, 42,
52 is interposed between each pressure control valve 21, 31, 41, 51 and each suspension cylinder 23, 33, 43, 53, and uses line pressure as pilot pressure, and when the line pressure is above a predetermined value. Each pressure control valve and each suspension cylinder are communicated with each other, and are cut off when the pressure is less than a predetermined value.

Furthermore, the bypass passage P4 connecting the high pressure passage P1 and the return passage P3 includes the high pressure passage P1 and the return passage P3.
A bypass valve 61 is interposed to control communication between the two. The bypass valve 61 is a pressure control valve that can control line pressure steplessly, and operates the main valve by controlling a large flow of hydraulic fluid using a main valve 61a and a small flow of hydraulic fluid using an orifice 61b. It is configured by a controlled electromagnetic pilot valve 61c. Note that the bypass valve 61 can also be configured only with a solenoid valve.

Each of the above electromagnetic pilot valves 21b, 31b
, 41b, 51b, and 61c are configured so that their operations are controlled by a controller (not shown), and the controller includes the above-described line pressure detection sensor 15 and each pressure sensor 24, 34, 44, 54. In addition to being connected, the vehicle height sensor installed at each wheel mounting part of the vehicle,
Known sensors (all not shown) are connected, such as a vehicle speed sensor that detects the vehicle speed, a longitudinal G sensor and a lateral G sensor that detect the behavior of the vehicle body, and a steering angle sensor that detects the amount of operation of the steering wheel.

[0011] The controller is connected to each of the above-mentioned sensors and has a preset control program and various maps (created based on data experimentally confirmed through theoretical consideration) necessary for processing the program. A microcomputer that stores and temporarily stores various data necessary for executing the program, and the microcomputer and each of the electromagnetic pilot valves 21b, 31b, 41b,
51b, 61c and drives each electromagnetic pilot valve based on each control signal from the microcomputer, and the suspension cylinder 23, 33, 43 of each wheel is connected to each wheel based on the signal from each sensor.
, 53, the necessary target control pressure is calculated, and the operation of each pressure control valve 21, 31, 41, 51 is controlled so as to achieve the target control pressure, and the normality or abnormality of each of the above sensors is determined and the bypass is performed. The operation of the valve 61 is controlled.

By the way, in this embodiment, as shown in detail in an enlarged manner in FIG.
, 41, 51, the main valves 21a, 31a, 41a, 51a are connected to a line pressure port 101 communicating with the high pressure passage P1, a low pressure port 102 communicating with the return passage P3, an output port 103 communicating with the supply/discharge passage P2, and a high pressure passage. A pilot chamber 105 connected to P1 via an orifice 104 and a pilot passage P5, and a spool 106 are provided.

The spool 106 is slidably assembled in the axial direction within a valve sleeve 108 that is fitted and fixed to the body 107 via an O-ring, and receives the pressure of the output port 103 at one end. Line pressure port 10
1 and the output port 103 and high the flow rate between the low pressure port 102 and the output port 103, and receives the pressure of the pilot chamber 105 at the other end, and this pressure causes the line pressure port to 101 and output port 10
It is designed to be driven in the direction of increasing the degree of flow between the low pressure port 102 and the output port 103 and lowering the degree of flow between the low pressure port 102 and the output port 103. Note that the spool 106 is biased toward the pilot chamber 105 by a spring 109 with a small spring force, and when the pressure in the pilot chamber 105 is approximately zero, the clip 111 fixed inside the valve sleeve 108
It is designed to move to a position where it engages with the

On the other hand, each pressure control valve 21, 31, 41, 5
1 pilot valves 21b, 31b, 41b, 51b are:
An inflow port 112 communicates with the pilot chamber 105 via a pilot passage P5, an outflow port 113 communicates with a return passage P3, and the degree of communication between these ports 112 and 113 is determined by a valve body 114 having a valve hole (small hole). Needle valve body 115 defined by moving in the axial direction
, and an electromagnetic drive means 116 that is coaxially provided on the back of the needle valve body 115 and drives the needle valve body in a direction to lower the flow rate in accordance with the value of the current applied.

The electromagnetic driving means 116 is composed of a core 117, a plunger (movable iron core) 118, a coil 119, etc., and the pressing force of the plunger 118 on the needle valve body 115 is adjusted according to the current value applied to the coil 119. The flow rate flowing from the inflow port 112 to the outflow port 113 is controlled, thereby controlling the pressure within the pilot chamber 105 (pilot pressure).

Each pressure control valve 21 configured as described above,
31, 41, and 51, when the current value applied to the coil 119 increases, the pressing force of the plunger 118 on the needle valve body 115 increases, and the flow rate flowing from the inflow port 112 to the outflow port 113 decreases. The pressure within pilot chamber 105 increases. Therefore, the spool 106 moves against the spring 109, and high-pressure hydraulic fluid is supplied from the high-pressure passage P1 to the supply/discharge passage P2, increasing the pressure applied to each suspension cylinder 23, 33, 43, and 53. . Furthermore, when the value of the current applied to the coil 119 decreases, the pressing force of the plunger 118 on the needle valve body 115 decreases, and the flow rate from the inflow port 112 to the outflow port 113 increases, which causes the pressure in the pilot chamber 105 to decrease. decreases. For this reason,
The spool 106 moves toward the pilot room 105,
High-pressure hydraulic fluid is discharged from the supply/discharge passage P2 to the return passage P3 to each suspension cylinder 23, 33, 43, 53.
The pressure applied to the

By the way, in this embodiment, as shown in FIG. 3, each pressure is applied to the suspension cylinder 23 disposed between the right front wheel and the vehicle body and the suspension cylinder 43 disposed between the right rear wheel and the vehicle body. Each pressure control valve 2 that controls
In the pilot valves 21b and 41b (provided in two stages, upper and lower), each plunger 118 is installed to the left of each needle valve body 115, and the plunger 118 is installed between the left front wheel and the vehicle body. Each pressure control valve 31, 5 controls the pressure applied to the suspension cylinder 33 provided between the left rear wheel and the vehicle body.
1 pilot valves 31b and 51b (provided in two stages, upper and lower), each plunger 118 is attached to the right side of each needle valve body 115, and when the vehicle turns, the inner wheel ( Each suspension cylinder (23, 43 or 33, 53) disposed between the vehicle body (right wheel when turning right or left wheel when turning left)
) Each plunger 118 of each pressure control valve (21, 41 or 31, 51) controls the pressure to each needle valve body 1.
It is arranged to be located outside of 15.

Therefore, in this embodiment, each suspension cylinder (23, Each pressure control valve (21, 41 or 31, 51) that controls the pressure to 43 or 33, 53)
The plunger 118 and needle valve body 115 of the pilot valve are subjected to outward acting force (centrifugal force) due to lateral acceleration generated when the vehicle turns. By the way, since this acting force acts in the direction of increasing the degree of communication between both ports 112 and 113 of each pilot valve (in the direction of lowering the pilot pressure), each pressure control valve (21, 41 or 31, 51
) is as shown in FIG. 4B, and approximates the data line Lo of the control map stored in the computer over the entire control range. Therefore, the pressure applied to each suspension cylinder (23, 43 or 33, 53) can be accurately controlled, and lifting of the inner wheel side at the time of limit roll of vehicle turning can be accurately prevented. By the way, this embodiment can be implemented by changing the layout of each pilot valve, and there is no secondary problem that occurs when changing the computer control map, and it is economical and performance efficient. It is also extremely good.

Note that the reason why no change appears in the characteristics in the large current region of the current-pressure characteristic B is that in the large current region, the electromagnetic force obtained by the electromagnetic drive means 116 of each pilot valve has an effect obtained by the above-mentioned lateral acceleration. This is because the influence of the same acting force is larger than that of the force. In addition, the current-pressure characteristics shown in C in Fig. 4 are for each suspension cylinder disposed between the outer wheel when the vehicle turns (the left wheel when turning right, or the right wheel when turning left) and the vehicle body. This is obtained by each pressure control valve (31, 51 or 21, 41) that controls the pressure to (33, 53 or 23, 43), and the characteristics in the small current region further deviate from the standard characteristic A. However, at this time (when the vehicle is turning), the characteristics of the large current region are utilized, so there is no problem with control at all.

[Brief explanation of drawings]

FIG. 1 is a hydraulic circuit diagram showing an embodiment of a vehicle suspension device according to the present invention.

FIG. 2 is a detailed enlarged sectional view of the pressure control valve shown in FIG. 1;

3 is a plan view showing the arrangement of pilot valves in each suspension cylinder and each pressure control valve shown in FIG. 1. FIG.

FIG. 4 is a diagram showing current-pressure characteristics of a pressure control valve.

[Explanation of symbols]

11...Reservoir, 12...Pump, 21, 31, 41, 5
1...Pressure control valve, 21a, 31a, 41a, 51a...main valve, 21b, 31b, 41b, 51b...pilot valve,
23, 33, 43, 53...Suspension cylinder, 1
01...Line pressure port, 102...Low pressure port, 103...
Output port, 104... Orifice, 105... Pilot chamber, 106... Spool, 112... Inflow port, 113...
Outflow port, 115...needle valve body, 116...electromagnetic drive means, 118...plunger, P1...high pressure passage, P2...supply/discharge passage, P3...return passage.

Claims (1)

[Claims] 1. A pump that discharges hydraulic fluid sucked from a reservoir into a high-pressure passage; a suspension cylinder that is arranged between each wheel and the vehicle body to extend and contract; and pressure applied to each of these suspension cylinders from the high-pressure passage. each pressure control valve includes a line pressure port communicating with the high pressure passage, a low pressure port communicating with the return passage connected to the reservoir, and a supply line connected to the suspension cylinder. An output port that communicates with the exhaust passage, a pilot chamber that is connected to the high pressure passage through an orifice, and one end of which receives the pressure of the output port and uses this pressure to lower the degree of communication between the line pressure port and the output port. The low pressure port is driven in a direction to increase the degree of communication between the low pressure port and the output port, and receives the pressure of the pilot chamber at the other end, and uses this pressure to increase the degree of communication between the line pressure port and the output port. a main valve having a spool driven in a direction to lower the flow rate of the output port; an inlet port communicating with the pilot chamber; an outlet port communicating with the return passage connected to the reservoir; An electromagnetic device that has a valve body that regulates the degree of flow through axial movement, and a plunger that is coaxially provided on the back of the valve body and drives the valve body in a direction that lowers the degree of flow depending on the energized current value. In a vehicle suspension system comprising a pilot valve having a driving means, the plunger of the pressure control valve controls pressure to the suspension cylinder disposed between the vehicle body and an inner wheel when the vehicle turns. A suspension device for a vehicle, wherein the pilot valve is arranged so that the pilot valve is located outside the valve body.