JP2909750B2 - Shock absorber with vehicle height adjustment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is disposed between a vehicle body and an axle in a vehicle to selectively exhibit a vehicle body vibration damping function and a vehicle height adjusting function. The present invention relates to a shock absorber with a vehicle height adjusting device.

[Conventional technology]

Hydraulic shock absorbers with a vehicle height adjustment device that work as a shock absorber in the suspension in normal conditions such as when driving a vehicle and work as a height adjustment device that lowers the vehicle height when stopping when the vehicle is stopped have already been proposed. (For example, Japanese Utility Model Laid-Open No. 61-182544), the basic configuration of which is shown in FIG.

According to such a conventional device, in the double-cylinder hydraulic cylinder mechanism, hydraulic oil moves between the upper chamber A and the lower chamber B in the cylinder 2 divided by the piston 1 as the piston rod 5 expands and contracts. It is made to do.

That is, in the extension stroke of the rod 5, the check valve 3 in the first passage provided in the piston portion functions as a closing valve, so that the operating oil in the upper chamber A is supplied to the piston forming the second passage. Through the hole 4 in the rod, it flows into the lower chamber B while generating a damping force when passing through the extension valve 6 disposed at the end of the passage. Then, at this time, the amount of oil corresponding to the retreat volume of the piston rod 5 from the cylinder 2 pushes and opens the check valve 8 of the base valve 7, and the oil flows from the reservoir chamber C between the cylinder 2 and the outer shell 9. It is refilled in the cylinder 2.

On the other hand, in the pressure stroke, the hydraulic oil in the lower chamber B on the side to be compressed pushes open the check valve 10 of the piston portion, passes through it without resistance, and flows into the upper chamber A. At this time, an amount of hydraulic oil corresponding to the volume of the piston rod 5 entering the cylinder flows from the lower chamber B through the pressure side valve 11 of the base valve 6 to the reservoir chamber C, and at this time, the damping by the pressure side valve 11 is performed. Force is generated.

Thus, the shock absorber operation for generating the damping force with respect to the expansion operation of the piston rod 5 is performed.

Instead of this, the vehicle height adjustment operation when the vehicle is stopped is performed by first controlling the pump 12 in response to a command from a controller (an electronic circuit device for processing a sensor signal or the like and outputting a command signal). The operation is started at 13 by driving in the normal rotation direction.

Thus, it sucked into the pump 12 reservoir oil tank 14 passes through while pushing open the check valve 15, via line R ₁ having the operate check valve 16, the piston rod 5
Is fed into the hollow small hole 17.

At the tip (piston side) of the small hole 17, a valve head urged upward by a pressure expanding spring 18 having a fixed lower end.
A switching valve consisting of 19 is provided, and the valve head 19 is pressed against the valve seat 20 against the acting force of the pressure expansion spring 18 by receiving the discharge pressure of the pump 12 through the small hole 17. The valve is the hole 4 that previously connected the upper chamber A and the lower chamber B.
And at the same time, a passage composed of the side hole 21 is formed between the small hole 7 and the upper chamber A.

Then, the chamber pressure of the upper chamber A, which rises in response to the discharge pressure, closes the check valve 3 of the piston portion and shuts off the flow of the hydraulic oil from the upper chamber A through the piston portion to the lower chamber B. I do.

The amount of oil discharged from the pump continues to the upper chamber A through the side hole 21.
To push down the piston 1 (vehicle height drop). At this time, the suspension spring 24 between the vehicle body 22 and the axle 23 works so as to resist the force of contracting the piston rod 5. Therefore, the pressure of the hydraulic oil in the upper chamber A increases in proportion to the downward movement of the piston 1.

The pump unit has a pressure detector (PH) is provided in the conduit R _1, which generates a signal to the pressure in the upper chamber A (pressure unit discharge portion) reaches the desired value, the signal In response, the controller issues a command to stop the forward rotation of the pump 12.

When the pump 12 is stopped, due to the conduit closure of R ₁ by operate check valve 16 in the same unit, the chamber pressure of the upper chamber A is held in pressure before stopping receives a reaction force of the suspension spring 24. Accordingly, the hydraulic cylinder 2 and its piston rod 5 can be kept in a contracted state against the suspension spring 24, and the vehicle height is fixed at a low position.

Next, the ascending operation is started by the reverse rotation of the pump 12 according to a command from the controller. Pump 12
With the reverse rotation, the hydraulic fluid in the tank 14 pushes and opens the check valve 25 to be pumped up by the pump 12, and then forms an annular flow path which is returned to the tank 14 via the throttle 26. Due to the restriction 26 in the annular flow path, pressure is generated at the discharge port a of the annular flow path,
This which was opened by acting on the operate check valve 16, as a result, the conduit R ₁ is opened.

Thus, the hydraulic oil of the upper chamber A which is loaded in compression direction by the reaction force of the suspension spring 24 is returned to the tank 14 via the through line R ₁ a small hole 17 of the piston rod 5. At this time, the chamber pressure of the upper chamber A decreases with the extension of the piston rod 5 (that is, the reduction of the suspension spring force).

The valve head 19 of the switching valve is kept pressed against the valve seat 20 by the chamber pressure of the upper chamber A, and the upper chamber A is pressed until the resultant force of the pressures acting on the front and back of the valve head 19 becomes smaller than the force of the pressure expansion spring 18. When the chamber pressure decreases, the upper chamber A and the lower chamber B again communicate with each other because they move upward in the figure by the compression force of the spring 18.

Thereafter, as the hydraulic oil in the upper chamber A moves to the lower chamber B, the chamber pressure in the upper chamber A rapidly decreases.

When this chamber pressure reaches the pressure determined by the pressure detector (PL) of the pump unit,
12 stops. Further, the piston rod 5 extends to a position where the reaction force of the suspension spring 24 is balanced with the weight of the vehicle body and there is no longer any force to extend the piston rod 5, and stops its operation.

At this time, since the force generated by the internal pressure of the cylinder 2 is negligibly small compared to the force generated by the bending of the suspension spring 24, the vehicle height is reduced to the original starting position (upper position) by this operation. Return to

In addition, R ₁ ′ denotes a pipeline for sending hydraulic oil to the other cylinder mechanism of the left and right wheels.

[Problems to be solved by the invention]

In the above-described conventional apparatus, the pressure of the upper chamber A when the valve head 19 of the switching valve starts to return upward during the vehicle height increasing operation (hereinafter referred to as the switching valve return point pressure) is the pressure before the start of the descent. Than by the reaction force of the compression spring 18, and this state is maintained thereafter. Therefore, at the time of the next descent, the amount of oil moving from the inside of the cylinder 2 to the reservoir chamber C due to the lowering of the piston 1 due to the fully opened residual oil amount is increased by that amount from the amount at the previous time. ,
The pressure in the reservoir chamber C (that is, the gas chamber D and the lower chamber B) at the end of the descent is added and gradually increased each time the vehicle height is repeatedly lowered and raised.

Therefore, in order to prevent this, a pressure start valve 27 is attached to the reservoir chamber C, and when the internal pressure of the chamber C reaches a set pressure, the valve 27 is opened to return the hydraulic oil in the reservoir chamber C to the return line R _2. Therefore, the tank 14 needs a configuration.

However, the pressure start valve 27 attached here must be attached to the outer shell 9, and the attachment position is the lower position of the shell communicating with the oil layer of the reservoir chamber C. At the time of assembling, it is required that the valve 27 be small in size so that the valve 27 at the lower part of the shell which faces the axle 23 does not hinder assembly. Further, the pressure release valve 27 which is located on the axle 23 side in the assembled state is required to have a high reliability capable of withstanding high frequency vibration input from the axle 23, and as a result, as a result, 27 had a high price, and there was a dislike that the entire apparatus became expensive.

Therefore, the present invention improves the reliability of a function of preventing an excessive increase in mechanism internal pressure based on the amount of residual oil accumulated in the buffer mechanism due to repetition of vehicle height adjustment in a hydraulic shock absorber with such a vehicle height adjustment function, and at the same time, reduces costs. The purpose of this study is to develop a device that can reduce emissions.

[Means for solving the problem]

According to the present invention, according to the present invention, there is provided a vehicle height adjusting device for injecting or discharging hydraulic oil to or from a hydraulic cylinder mechanism juxtaposed with a suspension spring in a suspension, and the cylinder is driven through an oil feed line by forward rotation of an external oil pump. In a hydraulic shock absorbing mechanism provided with a vehicle height adjusting device for lowering the vehicle height by supplying pressurized oil therein, an upper and lower section partitioned by a piston of the cylinder chamber between the oil feed line and the cylinder chamber. A valve is provided to switch between the chambers or to communicate between the upper chamber and the oil feed pipe, and a throttle passage communicating with the cylinder chamber is provided in parallel with the valve. This is achieved by a shock absorber with a vehicle height adjusting device configured to maintain an open circuit by the reverse rotation of the oil feed line pump until the vehicle body lift / return position extended by the reaction force of the suspension spring is reached. .

[Action]

That is, the pressure oil discharged from the external hydraulic pump and injected into the cylinder mechanism is guided to the upper chamber in the cylinder partitioned by the piston.

The introduction of pressure oil into the upper chamber of the cylinder raises the internal pressure of the upper chamber, thereby pushing down the piston. This piston operation is performed against the spring force of a suspension spring juxtaposed with the cylinder. .

Using a hollow hole in the piston rod, a valve arranged between the oil feed line and the cylinder cuts off a communication passage between the upper chamber and the lower chamber in the cylinder by the discharge hydraulic pressure from the pump. A passage that guides the discharged oil to the upper chamber through an oil feed pipe connected to the hole is opened.

The throttle passage juxtaposed to the valve communicates with the oil feed pipe via the lower chamber and the hollow hole while regulating the flow rate even in a valve state in which the communication between the upper chamber and the lower chamber is cut off. Function to keep.

On the other hand, the oil feed line is opened by the pump operation and closed at the stop, but it is not possible to discharge the hydraulic oil from the storage tank of the hydraulic oil by the forward rotation of the pump while discharging the hydraulic oil by the reverse rotation. No, but the passage to the storage tank is open.

Therefore, by continuing the reverse rotation of the pump from the bottom up to the operation return point of the valve in which the pipe internal pressure of the hydraulic oil returning to the storage tank through the oil supply pipe line from the bottom through the oil supply pipe line has reached the predetermined value, A return path for the hydraulic oil flowing from the cylinder side to the tank side is secured, and the chamber pressure of the lower chamber and the reservoir chamber returns to a predetermined set pressure.

When the operation of the pump is stopped, the valve opens the communication passage between the upper and lower chambers, and the hydraulic cylinder mechanism performs a shock absorber operation in a flow state of the hydraulic fluid regulated by the piston valve and the base valve in the communication passage.

〔Example〕

 Next, an illustrated embodiment of the present invention will be described.

FIG. 1 is a side view showing an embodiment of the present invention in a longitudinal section.
Besides the conventional device similar structures you have marks respectively identical symbols, the pressure release valve 27 and its return line R ₂ is omitted, this valve head 19 in the switching valve instead A gap 30 is provided between the outer periphery and the inner peripheral surface of the slide passage 4, and a spacer 31 having a shape as shown in the plan view of FIG. Between the spacers
The gap 30 communicates up and down through the notch 31a of the groove 31. Further, there is to wipe the manual opening and closing valve 33 between the connection between the feed line R ₁ and the hollow hole 17 of the piston rod 5.

Therefore, the main body of the cylinder mechanism according to this embodiment is mounted on the vehicle body 22 and the axle 23 by the upper and lower mounts 34 and 35, respectively. During this mounting, normally, since the main body 1 is placed on the rod compression, high internal pressure of the cylinder 2, since the inside of the hydraulic oil is a fear that leak outward, connected to a conduit R ₁ pump unit Until the operation, the manual on-off valve 33 is closed, and the hydraulic oil in the main body is placed so as not to leak outside.

Thus, the line D ₁ after connecting to the receptacle 36 of the piston rod 5, a該手dynamic off valve 33 operated by a tool such as a screwdriver, to open it, the line R ₁ and the cylinder 2 Secure communication paths.

In this state, the oil pump 10 in the pump unit
Of the time inoperative, no return of the hydraulic oil in the cylinder 2 of the through line R ₁ in the closed bottom of the operate check valve 16, the valve head 19 of the switching valve is anti to the acting force of it is拡圧18 And the upper chamber A and the lower chamber B communicate with each other through the through hole 4 and the side hole 21.

Therefore, the relative movement between the piston rod 5 and the cylinder 2 due to the vibration input in this state, the flow of the hydraulic oil between the upper and lower chambers A and B and the reservoir chamber C at this time causes Similarly, a compression damping force is generated, and the main body operates as a shock absorber.

The vehicle body descending operation by the vehicle height adjusting function when the vehicle is stopped is performed as follows.

That is, with the forward rotation of the oil pump 12 driven by the motor 13, the hydraulic oil in the tank 14 is discharged from the pipe line R _{1 in the same} manner as in the conventional device, passes through the hollow small hole 17, and expands the spring 18 of the switching valve.
And through the space of the receiving cylinder 32, the spacer
The air flows into the upper chamber A and the lower chamber B through the notched groove 31a and the gap 30 of 31.

Due to the flow of the pressure oil regulated by the narrow gap 30 forming the throttle passage, a pressure difference is generated between the front and back of the valve head 19, and the high pressure on the supply side causes the valve head 19 to act on the expansion spring 18 whose lower end is fixed at the lower end. It moves downward against the force and contacts the valve seat 20. Thereby, the switching valve cuts off the communication between the upper and lower chambers A and B, and at the same time switches the flow path so as to introduce the discharge oil from the oil pump 12 into the upper chamber A. The vehicle is kept at a low height.

Next, the vehicle height increasing operation by reversely rotating the oil pump 10 is performed in the same manner as in the conventional device.

That is, the operation check valve 16 is operated by the reverse rotation of the pump 12.
Is opened, the passage of the conduit R ₁ and the oil tank 14 communicates. On the other hand, in the cylinder mechanism held in the vehicle height lowered state, since the upper chamber A is maintained at a high chamber pressure by the reaction force of the suspension spring, the valve head 19 receiving this high chamber pressure becomes the valve seat 20.
There remains pressed state, the hydraulic oil in the upper chamber A which communicates via line R ₁ and the hollow small hole 17 is returned to the tank 14.

With the retreat of the hydraulic oil from the upper chamber A, the piston rod 5 is gradually pulled up by the action force of the suspension spring 24. Then, as the extension operation proceeds, the upper chamber A
And the reaction force of the suspension spring 24 decreases.

On the other hand, a force based on the differential pressure between the chamber pressure of the upper chamber A and the chamber pressure of the lower chamber B acts on the valve head 19, and when this force becomes smaller than the acting force of the pressure expansion spring 18, The valve head 19 moves upward away from the valve seat 20.

With this switching valve return point operation, the hydraulic oil in the upper chamber A thereafter flows toward the lower chamber B. Conduit R ₁ which stand the flow of hydraulic fluid from the upper chamber A is the internal pressure is rapidly reduced but the pump 12
There is as long as continues to reverse rotation, a flow path extending from the line R ₁ to the tank 14 is open.

In contrast to the supply amount of hydraulic oil from the pump unit to the cylinder mechanism during the preceding vehicle height lowering control, the discharge amount from the cylinder mechanism returned to the pump unit at the time of ascent is changed by the switching as in the conventional device. When it reaches the valve return point, it decreases by the amount remaining in the upper chamber A.

Therefore, the chamber pressure in the cylinder 2 temporarily increases due to the residual oil amount. However, since the hydraulic oil in the cylinder 2 through a narrow passage consisting of scraper grooves 31a in the gap 30 and the spacer 31 of the outer periphery of the valve head 19 gradually flows out to the conduit R _1, the reverse rotation of the pump 12 while the conduit R ₁ is opened, the hydraulic fluid is returned to the tank 14, the set pressure for before the start of the downward movement of the inner pressure of the cylinder mechanism, i.e., the normal vehicle Takano height position (1G position) The pressure can be reduced toward.

Therefore, in order to switch valve return point even after rotated in reverse to pump 1 continues to open the conduit R _1, has the following several means.

An operation chart of the first means is shown in FIG. That is, from the holding state in the vehicle height lowered position, in the open under the line R ₁ by the reverse rotation of the pump 12, room pressure of the upper chamber A continues to drop, appeared from time to time the chamber pressure in the conduit R ₁ , Can be detected by a pressure switch (PL).
The pressure setting of the pressure switch (PL) cannot be set to zero (atmospheric pressure) due to its structure, but is set as close as possible to practical use.

Thus, when the internal pressure of the conduit R ₁ reaches the set pressure of the pressure switch (PL) in its lowered, the switch (PL)
Operates and outputs a detection signal.

Therefore, the temporary, simultaneously with the output of the detection signal, if discontinued reverse rotation of the pump by the motor 13, since the line R ₁ by closing of the operate check valve 16 will be closed, the cylinder mechanism With the accumulation of the residual oil amount corresponding to the set pressure of the switch (PL) close to the atmospheric pressure, the internal pressure of the cylinder mechanism is gradually increased each time the preceding vehicle height drop and this return are repeated.

Therefore, even if the internal pressure of the cylinder mechanism drops past the switching valve return point and further exceeds the set pressure of the pressure switch (PL), the switching valve return operation is performed so that the reverse rotation operation of the pump 12 is maintained for a predetermined time. Starting from the point or the set pressure, the controller activates the delay circuit and outputs a stop signal after a predetermined time has elapsed.

Accordingly, even if the set pressure of the pressure switch (PL) is a relatively high value, if the delay time is set to a time necessary for sufficiently reducing the cylinder internal pressure, the residual pressure in the cylinder mechanism can be reduced. The generation of the oil amount can be eliminated. Further, since there is no need to dare to determine the return point of the switching valve beyond the set pressure of the pressure switch (PL), a secondary effect such as an increase in the degree of freedom in designing the switching valve is exhibited.

Then, in place of the pressure switch (PL) in this case, a pressure sensor that generates an output signal having a strength corresponding to the detected pressure is used, and the time when the signal output of the sensor reaches a predetermined value is used as a starting point. The delay time may be determined.

FIG. 4 is an operation chart showing another means for holding the pump in reverse rotation. In such a vehicle height increasing operation, the pump 12 starts reverse rotation according to a command from the controller, and the upper chamber A
And with the internal pressure of the conduit R ₁ is lowered, the vehicle height is raised.
Then, as long as this rise is caused by the reaction force of the suspension spring 24, after a certain period of time, the vehicle returns to the vehicle height rise position (1G point) where the vehicle body load and the reaction force are balanced, and at the same time, the cylinder The internal pressure also becomes atmospheric pressure.

Therefore, from the time when the pump 12 starts reverse rotation, the controller control that sets the elapsed time sufficient for the cylinder internal pressure to reach the atmospheric pressure as the pump operation time,
The intended reverse rotation of the pump can be maintained.

In this case, a pressure switch (PL) and a sensor instead of the pressure switch are not required, and the degree of freedom in setting the return point of the switching valve can be secured.

〔The invention's effect〕

According to the above-described configuration of the shock absorber of the present invention, even if residual oil is generated in the cylinder mechanism due to the vehicle height raising / lowering control operation, the pressure in the mechanism and the reservoir chamber is reduced without accumulating the remaining oil. Since the pressure can be adjusted to a constant value and the pressure release valve and its return line can be omitted, the cost can be reduced and the reliability can be improved.

Then, since the pump reverse time operation is maintained for a predetermined time after the switching valve is operated by time control, even if a residual oil amount is generated by one rising operation, the pump is operated in the next rising operation. Since the amount of oil discharged from the cylinder mechanism during the above-mentioned predetermined time period is increased by an amount corresponding to the increase of the internal pressure of the cylinder due to the amount of residual oil, the accumulation of the residual oil is prevented, and the internal pressure of the cylinder mechanism is reduced to at least a set value. It can always be kept at a close value.

And, by this duration control, the pressure setting at the switching valve return point can be selected relatively freely, and there is a secondary effect that the degree of freedom in designing the valve can be increased.

[Brief description of the drawings]

FIG. 1 is a side view showing a longitudinal section of an embodiment of the shock absorber of the present invention, FIG. 2 is a plan view of a main structural part in the above embodiment, and FIGS. 3 and 4 are operations in the shock absorber of the present invention. FIG. 5 is a vertical sectional side view showing an example of a conventional shock absorber with a vehicle height adjusting device. (Explanation of symbols) 1 ... piston, 2 ... cylinder 4 ... passage, 5 ... piston ring 12 ... oil pump, 14 ... tank 16 ... operate check valve 17 ... hollow small hole, 18 ... expansion spring 19 ... valve head, 20 ... valve seat 24 ... suspension spring, 30 ... gap 31 ... spacer, 31a ... chipped groove

Claims (1)

(57) [Claims] 1. A vehicle height adjusting device for injecting or discharging hydraulic oil to or from a hydraulic cylinder mechanism juxtaposed to a suspension spring in a suspension. The hydraulic oil is injected into the cylinder through an oil feed line by a positive rotation of an external oil pump. In a hydraulic shock absorbing mechanism provided with a vehicle height adjusting device for supplying and lowering a vehicle height, between the oil supply pipe line and a cylinder chamber, communication is provided between upper and lower chambers partitioned by a piston of the cylinder chamber. A valve is provided for switching the upper chamber to communicate with the oil feed pipe, and a throttle passage communicating with the cylinder chamber is provided in parallel with the valve. A shock absorber with a vehicle height adjusting device, characterized in that the oil feed line is kept open by reverse rotation of the pump until it reaches a vehicle body ascent / return position that has been extended by force.