JPH04103425A - Suspension control device for vehicle - Google Patents

Abstract

PURPOSE:To improve operability and riding comfortability at cornering with a simple constitution out of mainly rack and pinion by simultaneously controlling respective hydro-pneumatic suspension of right and left front wheels with a first piston rod and right and left rear wheels with a second piston rod. CONSTITUTION:A suspension control device 100 is constituted out of a first piston rod 12 with which the working fluid quantities in suspension cylinders 2A, 2B respectively provided on right and left front wheel parts are simultaneously controlled, a second piston rod 13 with which the working fluid quantities in suspension cylinders 2C, 2D respectively provided on right and left rear wheel parts are simultaneously controlled, and a rod control means 50 mentioned later with which right and left reciprocating motion of the first and second piston rods 12, 13 are individually controlled. The first piston rod 12 is provided with a first rack 15, the second piston rod 13 is provided with a second rack 16, and the first and second racks 15, 16 are engaged with a first pinion 17.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a suspension control device for a vehicle, and particularly relates to a so-called hydro 221matic suspension (a suspension control device for a vehicle body) installed between a vehicle body and each wheel. The present invention relates to a vehicle suspension control device that controls a suspension that adjusts and absorbs vibrations using liquid flow and gas elasticity.

[Background technology]

Conventionally, active suspensions have a fluid pressure cylinder interposed between the vehicle body and each wheel, and the working fluid pressure of the fluid pressure cylinder is controlled by a pressure control valve to suppress changes in the vehicle body posture. A device (active suspension device) has been developed. As this active suspension device, one that uses hydraulic pressure and one that uses gas pressure are known.

In suspension systems, microcomputer control has recently begun to be used in the form of auto-levelizers (vehicle height adjustment devices) and shock absorber damping force automatic adjustment systems. The idea is to correct changes in the vehicle height and posture due to the number of passengers and cargo by changing the spring stiffness of the suspension springs.

[Problem to be solved by the invention]

However, in the conventional hydraulic and gas-pressure active suspension devices described above, the engine drives the hydraulic pump and compressor, respectively, resulting in power loss. On the other hand, the auto-levelizer and shock absorber damping force automatic adjustment systems mentioned above are microcomputer-controlled, so they allow fine-grained posture control while driving, but they require control for each wheel part, and in addition to the need for vehicle height sensors. , it is necessary to provide various sensors such as a load sensor, a lateral acceleration sensor, and a longitudinal acceleration sensor, and the overall system configuration is complicated and inevitably expensive.

[Purpose of the invention]

The present invention has been made in view of the disadvantages of the conventional example, and its purpose is to have a simple structure, prevent deterioration of fuel efficiency, and improve maneuverability and ride comfort during cornering. An object of the present invention is to provide a suspension control device for a vehicle that can perform the following functions.

[Means to solve the problem]

The present invention provides a first piston port/7 door that simultaneously controls the amount of working fluid in each suspension cylinder that constitutes a hydropneumatic suspension installed on each of the left and right front wheels of a vehicle, and a a second piston rod that simultaneously controls the amount of working fluid in each suspension cylinder constituting the equipped hydropneumatic suspension; and rod control means for separately controlling the left and right reciprocating movements of the second piston rod. The 20-mouth/throat control means is the first. The first and second racks, which are each integrally installed on the second piston rod, mesh with the side racks, and their rotation shafts can reciprocate from side to side, and their rotation can be in a restricted or unrestricted state. This configuration includes a first pinion that can be set. This aims to achieve the above-mentioned purpose.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 7.

FIG. 1 schematically shows the configuration of an embodiment of the present invention.

In FIG. 1, symbols IA to ID indicate hydropneumatic suspensions that are interposed between the vehicle body (not shown) and each wheel, and that adjust and absorb vibrations of the vehicle body using the flow of liquid and the elasticity of gas. . These hydropneumatic suspensions IA, IB, IC
, ID are provided on the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel, respectively.

Hydropneumatic suspension IA.

IB, IC, and ID are suspension cylinders 2A, 2B, and 2B, respectively, which are attached to vehicle body side members (not shown).
2C, 2D and the relevant suspension cylinders 2A, 2B
, 2C, 2D, respectively, and one end is connected to each of the suspension pistons 3A, 3B, 3C, 3D, and the other end is connected to a left front wheel (not shown). , right front wheel.

A wheel side member 5A5B that individually supports the left rear wheel and the right rear wheel,
Rods 4A, 4B, 4 fixed to 5C, 5D respectively
C, 4D.

A working fluid storage area 6A containing working fluid (hydraulic oil) is formed in the upper part of the suspension piston 3A in the suspension cylinder 2A. Above the working fluid storage area 6A in the figure, there is a throttle valve 7A.
A gas chamber 8A is provided through the gas chamber, and nitrogen gas is stored in the upper part of the gas chamber. Therefore, vibrations of the vehicle body can be absorbed and adjusted by the flow of the working fluid and the elasticity (fluctuations in pressure) of the nitrogen gas.

Other hydropneumatic suspensions IB, I
C and ID are also similar to this. Also, working fluid storage areas 6A, 6B, and 6C.

6D are connected to cylinders IIA, IIB, IIC, and 11D that constitute the suspension control device 100 via hydraulic pipes 9A, 9B, 9C, and 9D, respectively.

This suspension control device 100 includes a first piston rod 1 that simultaneously controls the amount of working fluid in suspension cylinders 2A and 2B that are respectively installed on the left and right front wheels.
2, a second piston rod 13 that simultaneously controls the amount of working fluid in the suspension cylinders 2C and 2D installed on the left and right rear wheel portions, respectively; The second piston rod 12 and 13 are configured to include rod control means that separately controls the left and right reciprocating movements of the second piston rods 12 and 13, which will be described later.

To explain this in more detail, the first piston rod 12 is
Pistons 14A, 14B are provided at both ends thereof, and each piston 14A, 14B is equipped to slide within each cylinder cylinder IIA, IIB described above. That is, by the left and right reciprocating movement of the first piston rod 12 in the drawing, the pistons 14A and 14B move left and right, and as a result, the amount of hydraulic oil (pressure of hydraulic oil) in the suspension cylinders 2A and 2B is controlled. It has become so. Second piston rod1. NJ]+i is provided with pistons 14C and 14D at both ends thereof, and the amount of hydraulic oil in the suspension cylinder 2C2D is adjusted by moving the second piston rod 13 from side to side.

As shown in the figure, the first piston rod 12 is integrally equipped with a first rack 15 on the lower surface of its center, and on the other hand, the second piston rod 13 is equipped with a rack 15 on the upper surface of its center in the figure. Two racks 16 are integrally installed. A first pinion 17 is engaged with these first and second racks 15,16. The rotating shaft of the first pinion 17 can be connected to or disconnected from the rotating shaft of the first servo motor 18 via a clutch (not shown). That is, when the clutch is "ON", the first pinion 17 stops and rotates in response to the stop and rotation of the first servo motor 18, and its rotation is restrained, but the clutch is r
If it is '0FF (off)', the first tongion 17 can freely rotate and its rotation is not restricted. Here, the first servo motor 18 is connected via a connecting member 19 to a third rack 20 that can reciprocate in the left-right direction in the first rotation along a guide means (not shown). This third rack 20 is meshed with a second pinion 21 that drives the rack 20.
It is integrally fixed to the rotating shaft of the servo motor 22. This second servo motor 22 is actually fixed to the vehicle body (not shown). and a first servo motor 18. Second servo motor 22. The clutch and the clutch are controlled by an EC1J0 as a main control unit composed of a microcomputer or the like. This EC1J30 has
As shown, a steering wheel angle signal is input from a steering angle sensor (not shown), a vehicle speed signal is input from a vehicle speed sensor (not shown), and a clutch switch signal is input from a clutch switch (not shown). And this EC1J30
Now, various types of controls are performed, which will be described later. In this embodiment, these racks F5.1620,
Pinion 17, 21. A rod control means 50 is constituted by the servo motor 18° 22, the connecting member 19, and the ECU.

Next, the overall operation of the above embodiment will be explained with reference to FIGS. 3 to 6, focusing on the flowchart of FIG. 2 showing the main control operations of the ECU 3O.

■ [In the case of roll control shown in Figure 2 (1)] Here,
A description will be given of when the vehicle is cornering to the right (turning right).

First, the ECU 3O inputs signals from a vehicle speed sensor and a steering angle sensor (not shown) to calculate the vehicle speed and steering angle (step 5IOI). Next, the ECU 3O determines the rotation axis of the first pinion 17 corresponding to these values from a map (this is stored in the internal memory in advance) as shown in FIG. Find the amount of movement (S
102), and controls the second servo motor 22 accordingly (3103). As a result, as is clear from FIG. 3, the second servo motor 22 is rotated to the left,
The second pinion 21 rotates to the left and the first servo motor 1
8, the rotating shaft of the first pinion 17 moves to the left side of the vehicle body, but at the same time the first pinion 17 meshes with the pinion 17 of the cylinder 1. The second rack 15.16 also moves to the left. The operation at this time is shown in FIG. For this reason, the first piston rod 12. Both the second piston rods 13 move to the left side of the vehicle body, and the hydraulic oil is pressed by the pistons 14A and 14C toward the suspension cylinders 2A and 2C, respectively, and the rods 4A and 4C move downward,
As the pistons 14B and 14D move to the left, the oil pressure in the cylinders IIB and 11D decreases, so the rods 4B and 4
D moves up. As a result, the vehicle height on the left side of both the front and rear wheels increases and the vehicle height on the right side decreases, suppressing rolling of the vehicle body to the left caused by centrifugal force during right cornering, and keeping the vehicle level. It will be dripping. In this case, as shown in FIG.
The amount of movement of the rotating shaft is controlled to increase as the front wheel steering angle and vehicle speed increase.As a result, the greater the rolling, the greater the suppressing force, so the vehicle body is always kept almost horizontal. On the other hand, when cornering to the left, the rotation axis of the first pinion moves to the right, so that the vehicle body is kept horizontal in this case as well.

(2) [In the case of roll rigidity control shown in FIG. 2 (2)] In this case, it is assumed that the rotation amount of the second servo motor 22 is controlled in the same manner as in (2) above. Here again, the case of right cornering will be explained in the same way as above.

First, in ECtJ30, the steering angle change rate is calculated from the output of the steering angle sensor (step 5201). Then, the rotation angle of the first pinion, that is, the rotation amount of the first servo motor, which corresponds to this steering angle change rate and the amount of movement of the rotation axis of the first pinion 17 required for roll control, is set as Calculate from a map as shown in Figure 4 (a map whose variables are the rate of change in the steering angle and the amount of movement of the first pinion rotating shaft).5202
), based on which the first servo motor 18 is controlled (
S203). FIG. 6 shows the state during steady turning, that is.

The operation when the front wheel steering angle change rate is 0 is shown.

In the case of FIG. 6, the amount of movement of the first piston rod 12 is the amount of movement of the rotating shaft of the first pinion 17 plus the amount of movement due to the rotation of the first pinion 17. On the other hand, the amount of movement of the second piston rod 13 is the amount of movement of the rotating shaft of the first pinion 1'7 minus the amount of movement caused by the rotation of the first pinion 17.

As a result, the amount of movement of the second piston rod 13 is smaller than the amount of movement of the first piston rod 12, and the left and right load movement on the front side is larger than the left and right load movement on the rear side, so that front roll rigidity>rear roll rigidity becomes. Therefore, in this case, the turning of the vehicle body becomes understeer, and stability is ensured. On the other hand, if the rotation of the first pinion is reversed from that shown in FIG. 6, the rear roll rigidity increases, resulting in oversteer.

Therefore, in this embodiment, as is clear from FIG. 4, when the front wheel steering angle change rate at the start and end of a turn is large, oversteer occurs, ensuring good responsiveness, and During a steady turn when the steering angle change rate is 0,
Understeer occurs and stability is ensured. In Figure 4, between the straight line where the front wheel steering angle change rate is large and the straight line where the front wheel steering angle change rate is 0, there are actually many straight lines with different slopes depending on the steering angle change rate. ing.

■ [In the case of equal load control on the left and right wheels shown in Fig. 2 (3)] The ECU 3O determines whether or not a clutch switch ON signal has been input from a clutch switch (not shown) (Step 5301), and if the ON signal has been input. in case of,
The clutch is turned off (3302). As a result, the rotation of the first nion 17 becomes unrestricted, that is, free. For this reason, the first piston rod 12. second piston rod 1
3 moves according to the difference in left and right loads, and stops when the left and right loads are balanced. The operation at this time is shown in FIG.

In this way, by making the left and right loads equal,
When stuck, it is possible to secure grip (frictional force between the tire and the road surface) on both the left and right sides, and the spring (
In order to stroke the suspension piston by means other than the action of a spring (which is interposed in parallel with the suspension cylinder between the vehicle body side and the wheel side and supports the static load of the vehicle body),
A long-stroke suspension can be constructed using a stiff spring with a large spring constant, and therefore the running performance on rough roads with large irregularities can be improved.

As explained above, according to this embodiment, rolling can be suppressed and roll rigidity can be controlled with a simple configuration, so it is possible to improve maneuverability and ride comfort during cornering. First, without the need for a pump or compressor. Since the force required to move the second piston rod is only the driving force of the servo motor, there is almost no loss of engine power and deterioration of fuel efficiency can be prevented. Furthermore, since the wheel loads can be equalized on the left and right sides, grip can be ensured on both the left and right sides when the vehicle is stuck, and drivability on rough roads can also be improved. In addition to these, the control method is also simple, as shown in the flowchart of FIG.

〔Effect of the invention〕

Since the present invention is constructed and functions as described above, according to this, the first piston rod simultaneously controls the hydropneumatic suspension of the left and right front wheels of the vehicle, and the second piston rod controls the hydropneumatic suspension of the left and right rear wheels. Because it is configured to control the hydropneumatic suspension of both parts simultaneously, it is easier to control than when controlling each wheel part separately. In addition, since the front and rear wheels are independently controlled, it is possible to suppress the roll during turning and control the roll rigidity, and the rotation of the first piston can be set in an unrestricted state (free state). The left and right wheel loads can be made equal,
This ensures sufficient grip on both the left and right sides when the vehicle is stuck, and improves drivability on rough roads. Also, unlike active suspension, it does not require an oil pump or compressor; The force required to move the second piston rod is only the driving force of the servo motor, for example as in the above embodiment, so there is almost no loss of engine power and it is possible to prevent deterioration of fuel efficiency. . Therefore, with a simple configuration centered on a rack and a binion, it is possible to improve maneuverability and ride comfort during cornering, improve running performance on rough roads, and prevent deterioration of fuel efficiency. It is possible to provide an unprecedented and excellent suspension control device that can perform the following functions.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the overall configuration of an embodiment of the present invention,
FIG. 2 is a flowchart showing the main control operations of the ECU shown in FIG. 1, and FIG. 3 is a diagram showing an example of a map for calculating the amount of movement of the rotation axis of the first binion during roll control.
Fig. 4 is a diagram showing an example of a map for calculating the rotation angle of the first binion during roll rigidity control, Fig. 5 is an explanatory diagram of roll control operation during right cornering, and Fig. 6 is a diagram showing an example of a map for calculating the rotation angle of the first binion during right cornering. FIG. 7 is an explanatory diagram of the operation of roll rigidity control, and FIG. 7 is an explanatory diagram of the operation of left and right wheel equal load control. ■A~ID...Hydropneumatic suspension, 2A~2D...Suspension cylinder, 12...First piston rod, 13
...Second piston rod, 5...First rack, 6...Second rack, 7...First binion, 0. ...Rondo control means, OO...Suspension control device.

Claims (1)

[Claims] (1). A first system that simultaneously controls the amount of working fluid in each suspension cylinder that makes up the hydropneumatic suspension installed on the left and right front wheels of the vehicle.
a second piston rod that simultaneously controls the amount of working fluid in each suspension cylinder that constitutes the hydropneumatic suspension installed on the left and right rear wheels, and the first and second piston rods. rod control means for separately controlling left and right reciprocating movements of the piston rods, and the rod control means includes first and second racks that are integrally installed on the first and second piston rods, respectively; A suspension control for a vehicle characterized by comprising a first pinion that meshes with a rack, has a rotating shaft that can reciprocate from side to side, and whose rotation can be set to a restrained or unrestrained state. Device.