JPH0716483Y2 - Hydraulic suspension - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a hydraulic suspension that controls a vehicle body position and a vehicle attitude by adjusting a vehicle height.

(Prior Art) Conventionally, as a hydraulic suspension, for example, JP-A-59-
The one described in FIG. 4 of Japanese Patent No. 124419 is known.

This conventional suspension is interposed between a spool type hydraulic control valve for adjusting a hydraulic pressure from a hydraulic pressure source to a predetermined control pressure according to a control command and a vehicle body side and a wheel side. And a hydraulic actuator that operates at.

(Problems to be solved by the invention) However, in such a conventional suspension, since a spool type valve was used as a hydraulic control valve, a valve that slides between spools is used. The liquid pressure leaks from the gap between the hole and the liquid, causing the following problems.

For example, when the vehicle is parked for a long time, the hydraulic fluid leaks to the discharge path side, which lowers the vehicle height and impairs the appearance.

When starting from a parked vehicle, there are practical problems such as waiting for a rise in vehicle height (return) before the vehicle can travel.

Therefore, as a solution to such a problem, in order to prevent the hydraulic fluid from leaking to the discharge passage side, the hydraulic pressure generated by stopping the hydraulic pump is provided in the supply passage to the hydraulic control valve and the discharge passage from the hydraulic control valve. It is conceivable to provide a check valve for blocking the flow from the hydraulic pressure control valve by using the hydraulic pressure signal when the pressure value becomes a predetermined value or less.

However, when an accumulator is used as a hydraulic source for the purpose of reducing the pump capacity of the hydraulic pump, the hydraulic fluid including the accumulator, which is the hydraulic source, is enclosed in a closed circuit. Due to the pressure transmission due to the leak, the pressure changes in the direction where the closed circuit filled with hydraulic fluid becomes the same pressure, that is, the pressure transmission via the hydraulic control valve increases the pressure on the hydraulic actuator side due to the influence of the accumulator pressure. The pressure changes, which in turn causes the vehicle height to rise.

(Means for Solving the Problem) The present invention has been made for the purpose of solving the above-mentioned problems, and in order to achieve this object, the present invention controls the hydraulic pressure from a hydraulic pressure source. A hydraulic fluid equipped with a spool-type hydraulic pressure control valve for setting a predetermined control pressure in response to a command, and a hydraulic pressure actuator that is interposed between the vehicle body side and the wheel side and that operates with the control pressure from the hydraulic pressure control valve. In the pressure suspension, as the hydraulic pressure source, an accumulator is provided in the supply passage from the hydraulic pump to the hydraulic control valve, and the hydraulic control is performed in the supply passage upstream of the accumulator and the discharge passage from the hydraulic control valve. Pilot check valves that allow the flow toward the valves and prevent the opposite are provided respectively, and the pilot check valve on the discharge passage side controls the hydraulic pressure on the upstream side of the pilot check valve on the supply passage. If this pilot pressure is a predetermined value or more as the pilot pressure, the valve is opened to allow reverse flow, and the pilot check valve on the supply path side uses the discharge path fluid pressure upstream of the pilot check valve on the discharge path as the pilot pressure. When the pilot pressure is equal to or higher than a predetermined value, the valve is opened to allow the reverse flow.

(Operation) In the hydraulic suspension of the present invention, as described above, since the pilot check valves that allow the flow toward the hydraulic control valve and prevent the reverse are provided on both the supply and discharge paths, respectively. When the vehicle is parked or stopped when the hydraulic pump is stopped, liquid leakage to the discharge path is suppressed, and a decrease in vehicle height is prevented.

Furthermore, the pilot check valve on the supply path side is configured to open when the discharge path hydraulic pressure on the upstream side of the discharge path side pilot check valve is equal to or greater than a predetermined value, so pressure transmission due to leakage in the spool type hydraulic control valve, Even if the pressure in the closed circuit including the accumulator filled with hydraulic fluid changes in the same pressure direction, the pilot check valve on the supply path side allows the fluid to escape so that the pressure does not exceed the prescribed pressure. The rise is prevented.

Since the pilot check valve on the discharge path side is opened when the hydraulic pressure from the hydraulic pump is equal to or higher than a predetermined value, the hydraulic pump is driven and the vehicle height adjustment operation is performed. Does not hinder the vehicle height adjustment operation.

Therefore, after securing the vehicle height adjusting operation, the vehicle height can be kept substantially constant by the synergistic effect of the vehicle height decrease prevention effect and the vehicle height increase prevention effect when the vehicle is parked or parked.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

In describing this embodiment, a hydraulic suspension mounted on an automobile will be taken as an example.

First, the configuration will be described.

The hydraulic suspension A of the embodiment, as shown in the drawings,
The main components are an oil tank 1, a suction passage 2, a hydraulic pump (hydraulic pressure pump) 3, a supply passage 4, a hydraulic control valve (hydraulic pressure control valve) 5, a control pressure passage 6, a hydraulic actuator (hydraulic actuator) 8, Discharge path 9, accumulator 10,
It is equipped with pilot checks 11 and 12, and pilot pressure lines 13 and 14.

The hydraulic pump 3 is a pump for supplying the hydraulic oil sucked from the oil tank 1 through the suction passage 2 to the supply passage 4,
The suction passage 2 is connected to the suction port 3a of the hydraulic pump 3.

An oil filter 20 is provided at the end of the suction passage 2 to connect the supply passage 4 and the discharge passage 9 with each other.
The relief valve 22 that regulates the upper limit pressure of the supply passage 4 to a predetermined pressure is provided in the valve 21.

The hydraulic control valve 5 is provided in the middle of the branch passage of the supply passage 4 for each of the four wheels, and controls the hydraulic oil by the accumulator pressure Pa from the accumulator 10 to control the command current value ic.
An electromagnetic proportional solenoid valve that sets a predetermined control pressure Pc according to the above is used as a spool type valve having a spool that can slide back and forth with respect to a valve hole in a valve body (that is, this hydraulic control valve 5 Is, for example,
Various types described in Japanese Patent No. 62-1611 are conceivable. ).

The hydraulic control valve 5 is provided with a supply port 5a, a discharge port 5b, and a control pressure port 5c, a supply passage 4 is connected to the supply port 5a, and a discharge passage 9 is connected to the discharge port 5b. The control pressure line 6 is connected to the pressure port 5c.

A valve solenoid (not shown) provided with the hydraulic control valve 5 processes an input signal from the input sensor group 50 such as a stroke sensor according to a predetermined control processing condition, and outputs a control command current value ic to each valve 5. A vehicle height control module 51 for sending out is connected (specifically, the control described in Japanese Patent Laid-Open No. 62-1611 can be considered).

The hydraulic actuator 8 is interposed between the on-spring body side 80 and the unsprung wheel side 81, which are suspension parts of the four wheels, and is operated by the control pressure Pc from the hydraulic control valve 5. The actuator includes a cylinder 82, a piston 83, and a piston rod 84.
Inside, a piston upper chamber 85 having a small pressure receiving area and a piston lower chamber 86 having a large pressure receiving area are defined.

Then, the hydraulic oil having the control pressure Pc from the control pressure passage 6 is transferred to the rod passage.
When supplied through 87 and the piston passage 88, the relative distance between the vehicle body side 80 and the wheel side 81 (the higher the pressure is, the larger) is determined according to the pressure level.

The control pressure passage 6 is an oil passage that connects the hydraulic control valve 5 and the hydraulic actuator 8.

One end of the discharge passage 9 is connected to the discharge port 5b of the hydraulic control valve 5 and the other end is opened to the oil tank 1, and an oil cooler is provided on the oil tank 1 side of the discharge passage 9. 90 is provided.

The accumulator 10 is a large-capacity reservoir provided in the middle of the supply path 4 from the hydraulic pump 3 to the hydraulic control valve 5, and stores the hydraulic oil supplied from the hydraulic pump 3 having a small discharge capacity and has a predetermined capacity. It functions as a hydraulic power source that maintains the accumulator pressure Pa.

The pilot check valves 11 and 12 are provided on the upstream side of the accumulator 10 in the middle of the supply passage 4 and the discharge passage 9 to allow the flow toward the hydraulic control valve 5 and prevent the reverse.

A pilot pressure oil passage 14 connected to the discharge passage 9 upstream of the pilot check valve 12 is guided to one pilot check valve 11 so that the oil pressure between the pilot check valve 12 and the hydraulic control valve 5 is a predetermined value or more. It will open when
The hydraulic oil is discharged to the hydraulic pump 3 side.

To the other pilot check valve 12, the pilot pressure passage 13 connected to the supply passage 4 at the upstream position of the pilot check valve 11 is guided, and the pressure from the hydraulic pump 3 is opened at a predetermined value or more to open the hydraulic fluid. When discharge is allowed and the pressure from the hydraulic pump 3 is less than a predetermined value, the flow from the hydraulic control valve 5 to the oil tank 1 is blocked.

Next, the operation will be described.

(B) When hydraulic pump is driven For example, sprung acceleration is detected when the hydraulic pump 3 is driven and the vehicle height is adjusted, and for example, sprung acceleration is detected, and the vehicle height is adjusted based on the detection signal to keep the vehicle horizontal. The case of performing control will be described.

The hydraulic oil is driven by the hydraulic pump 3 to be supplied to the accumulator 10 after passing through the pilot check valve 11 of the supply path 4, and the accumulator 10 supplies a predetermined accumulator pressure Pa.
The hydraulic oil is guided to the supply port 5a of the hydraulic control valve 5.

Then, in the hydraulic control valve 5, the internal spool is actuated by the control command current value ic, and is hydraulically controlled to the control pressure Pc corresponding to the control command current value ic and is guided to the control pressure path 6, and by this control pressure Pc. The hydraulic actuator 8 is operated to increase or decrease the relative distance between the sprung and unsprung parts to perform the vehicle height adjusting operation.

When the hydraulic control valve 5 is operated, a part of the hydraulic oil introduced to the supply port 5a for hydraulic control is discharged to the discharge port.
Although it is necessary to discharge from 5c to the oil tank 1 after passing through the discharge passage 9, the check valve on the discharge passage 9 side is used as a pilot check 12 so that the hydraulic pressure from the hydraulic pump 3 opens at a predetermined value or more. Therefore, it does not hinder the vehicle height adjustment operation described above.

(B) When the hydraulic pump is stopped Since the hydraulic pump 3 is stopped for a long time, when the vehicle is parked or stopped, the pressure level of the pilot pressure passages 13 and 14 becomes a very small level close to zero due to the stop of the hydraulic pump 3. Both pilot check valves 11 and 12 that are opened by pilot pressure are closed.

In this way, the pilot check valves 11 and 12 on both the supply and discharge passages 4 and 9 are closed, so that the flow of hydraulic oil from the hydraulic control valve 5 is blocked, and both pilot check valves 11 and 1 are closed.
Hydraulic fluid upstream of 2 is contained in the circuit.

Therefore, the hydraulic fluid is prevented from leaking from the discharge passage 9 to the oil tank 1 due to the leak in the hydraulic control valve 5 of the spool type, and the vehicle height is prevented from lowering due to the leak.

Further, due to the pressure transmitting action associated with the leak in the spool type hydraulic control valve 5, the pressure in the closed circuit including the accumulator 10 in which the hydraulic oil is sealed changes in the same pressure direction.
Upstream from pilot check valve 12 (hydraulic control valve 5
Side), the hydraulic pressure of the discharge passage 9 gradually rises and becomes equal to or higher than a predetermined pressure, and the pilot check valve 11 is opened by the hydraulic pressure guided to the pilot check valve 11 via the pilot pressure hydraulic passage 14 to open the pilot check valve 12. The pilot check valve 11 is opened and closed with a predetermined pressure as a boundary such that the downstream hydraulic pressure is relieved to the hydraulic pump 3 side, and the downstream hydraulic pressure is regulated to a predetermined value.

Therefore, the inside of the closed circuit in which the hydraulic oil is sealed does not exceed the predetermined pressure set by the pilot check valve 11, and the increase in vehicle height due to the leak is prevented.

As described above, the hydraulic suspension A of the embodiment has the following features.

After securing the vehicle height adjustment operation, the vehicle height can be kept almost constant by the synergistic effect of the vehicle height decrease prevention effect and the vehicle height increase prevention effect when parking or stopping, and the appearance is impaired when parked for a long time. Or, you can start immediately when starting from parking.

Since the pressure of the hydraulic oil enclosed by both pilot check valves 11 and 12 is regulated to a predetermined pressure, it has a fail-safe function for equipment such as the piping system and pressure control valve 5,
Not only when the vehicle is parked and parked, but also when the vehicle weight is excessively heavy, the hydraulic pump 3 breaks down, or the like, it is possible to prevent danger.

Unlike the hydraulic control valve 5, ..., Two pilot check valves 11 and 12 are not provided for each unit, so that the device cost can be reduced.

Although the embodiment has been described with reference to the drawings, the specific configuration is not limited to this embodiment, and even if there is a design change or the like within a range not departing from the gist of the invention, the invention is included in the invention. .

For example, a gas accumulator having an orifice on the inlet side is provided in the middle of the control pressure path 6 to form a gas spring for the hydraulic actuator 8, and the hydraulic actuator 3 is limited by the restriction of the amount of oil in and out by the orifice.
A so-called shock absorber function that damps and absorbs the vibration that is input to may be exerted.

(Effect of the Invention) As described above, in the hydraulic suspension of the present invention, an accumulator is provided as a hydraulic pressure source in the supply path from the hydraulic pump to the hydraulic control valve, and the downstream of the accumulator is provided. Side supply passage and discharge passage from the hydraulic control valve are equipped with pilot check valves that allow flow toward the hydraulic control valve and prevent the reverse, respectively.The pilot check valve on the discharge passage side is a hydraulic pump. Since the hydraulic pressure from the valve is opened above a specified value and the pilot check valve on the supply path side is opened above the exhaust path hydraulic pressure on the upstream side of the pilot check valve on the discharge path side, it is inexpensive. In addition to ensuring the vehicle height adjustment operation by the system, the vehicle height can be kept almost constant by the synergistic effect of the vehicle height decrease prevention effect and vehicle height increase prevention effect when parked and parked. The effect that the safety function is exhibited is obtained.

[Brief description of drawings]

The drawing is an overall view showing a hydraulic suspension according to an embodiment of the present invention. A ... Hydraulic suspension 1 ... Oil tank 2 ... Suction passage 3 ... Hydraulic pump (hydraulic pump) 4 ... Supply passage 5 ... Hydraulic control valve (hydraulic control valve) 6 ... Control pressure passage 8 …… Hydraulic actuator (hydraulic actuator) 9 …… Discharge path 10 …… Accumulator 11,12 …… Pilot check valve 13,14 …… Pilot pressure oil path

Claims (1)

[Scope of utility model registration request] 1. A spool type hydraulic pressure control valve for controlling a hydraulic pressure from a hydraulic pressure source to a predetermined control pressure according to a control command, and a spool type hydraulic pressure control valve provided between the vehicle body side and the wheel side. A hydraulic actuator that operates at a control pressure of, and an accumulator is provided in the supply path from the hydraulic pump to the hydraulic control valve as the hydraulic pressure source, and the supply on the upstream side of the accumulator Pilot check valves that allow the flow toward the hydraulic control valve and prevent the opposite are provided in the discharge passage from the passage and the hydraulic control valve, and the pilot check valve on the discharge passage side is the pilot of the supply passage. When the pilot pressure is the hydraulic pressure upstream of the check valve and this pilot pressure is a predetermined value or more, the valve is opened to allow reverse flow, and the pilot check valve on the supply path side is Hydraulic suspension the pilot pressure discharge path fluid pressure upstream of the pilot check valve as the pilot pressure is characterized by being configured so as to allow backflow opened if more than a predetermined value Detchi.