JPS6234561B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in hydroneumatic suspensions used in automobiles.

Hydroneumatic suspensions are installed in pairs at the front and rear wheels of a car, and are usually equipped with an auto-leveling mechanism, which allows the suspension unit to adjust when the weight of the vehicle changes due to passengers getting on and off or loading and unloading luggage. The system automatically corrects the vehicle's posture by supplying and discharging the pressure oil inside. In addition, this auto-leveling mechanism has a damper function that determines whether the change in vehicle height is not temporary and allows the auto-leveling mechanism to function before supplying or discharging the pressure oil. By delaying the operation for an appropriate amount of time, it cooperates with the gas spring function of the accumulator attached to the suspension unit, and eliminates the waste caused by auto-leveling against wheel bounce, bounding, pitching, etc. that occur when driving on rough roads. The structure is such that the suspension unit does not suffer from hunting due to excessive oil consumption or continuous operation of supplying and discharging hydraulic oil within the suspension unit.

Furthermore, in the case of such a hydroneumatic suspension, in addition to being equipped with an auto-leveling mechanism as described above, it is also necessary to provide a vehicle height selection function so that the vehicle height can be adjusted arbitrarily. . An example of this vehicle height selection control will now be described in detail with reference to FIG.

Normally, the first switching valve 4 connected in series to the pressure oil supply passage 3 of the parallel hydraulic circuit of the front suspension unit 1 and rear suspension unit 2 is opened, and the second switching valve 5 is opened or closed. In addition, the third switching valve 7 disposed in the drain passage 6 is opened, and the pressure oil supply passage 3 between the first and second switching valves 4 and 5 and the third switching valve 7 are opened. The fourth switching valve 9 disposed in the passage 8 that communicates the is closed. As a result, pressure oil from the hydraulic source 10 consisting of the oil pump 11, unload valve 12, and main accumulator 13 is transferred to the first switching valve 4 and the first check valve 14 (when the second switching valve 5 is closed).
It is led to the inlet 2a of the rear suspension unit 2 via the inlet 2a of the rear suspension unit 2, and to the inlet 1a of the front suspension unit 1 via the first switching valve 4, first and second check valves 14, 15. As a result, each suspension unit 1, 2
The built-in automatic leveling mechanism (not shown) functions normally as a damper, and when the vehicle height changes due to passengers getting on and off, loading and unloading luggage, etc., the hydraulic fluid in each suspension unit 1 and 2 is released. automatically adjusts the vehicle height to the standard position.

Even when driving, especially when cornering, the first to fourth switching valves 4, 5, 7, and 9 are all closed by a G sensor (not shown) that detects rolling of the vehicle body, and as a result, the suspension units 1 and 2 are closed. In the oil-locked state, the suspension units 1, 2 function as mere gas springs due to the accumulators 1c, 2c attached to their upper portions, thereby suppressing rolling.

When lowering the vehicle height to a predetermined height when a passenger gets on and off, the first and second switching valves 4 and 5 are closed, and the third and second switching valves are closed.
The fourth switching valves 7 and 9 are opened. As a result, the pressure oil supply side of each suspension unit 1, 2 becomes lower than the internal pressure of each suspension unit 1, 2, so that the pressure oil in the units 1, 2 is supplied to the first and second relief valves 16, 17. The oil is drained into the oil reservoir 18 via the relief valves 16, 17 and the fourth and third switching valves 9, 7 until the oil reaches a predetermined pressure, thereby lowering the vehicle height to a predetermined height. Here, check the relief valve 1 on the front suspension unit 1 side.
The set pressure 7 is set higher than the set pressure of the relief valve 16 on the rear suspension unit 2 side to prevent the front side from lowering the vehicle height more than necessary, and thereby to supply pressurized oil when the vehicle height returns to normal. This avoids prolonging the recovery time.

When jacking up during tire replacement, the first and fourth switching valves 4 and 9 are opened, the third switching valve 7 is closed, and the second switching valve 5 is opened or closed. As a result, each suspension unit 1,
2, the hydraulic pressure from the hydraulic source 10 is applied to the first switching valve 4, the check valve 14, or the check valves 14, 15 (when the second switching valve 5 is in the closing operation).
At the same time as both suspension units 1 and 2 begin to extend, pressure oil is also supplied from the outlets 1b and 2b via the fourth switching valve 9, and the suspension units 1 and 2 are quickly extended. Stretch to the maximum. In addition, when lowering the vehicle height quickly by moving the oil to the oil drain position, the first switching valve 4 is closed, the second
The third and fourth switching valves 5, 7, and 9 are opened. As a result, the pressure oil supply side of each suspension unit 1, 2 becomes lower than the internal pressure of the units 1, 2, so that the pressure oil in both suspension units 1, 2 is transferred from the inlets 1a, 2a to the second switching valve 5, The internal pressure is drained through the fourth switching valve 9 and the third switching valve 7 until it becomes zero, thereby reducing the vehicle height to a minimum.

As described above, each of the front and rear suspension units can be operated to select the vehicle height as needed. When selecting the vehicle height,
For example, when draining the hydraulic oil in the suspension units 1 and 2 from the normal vehicle height position, each hydraulic oil chamber 1d,
Hydraulic oil chamber 1 of 2d and accumulators 1c and 2c
Since e and 2e are in communication with each other, as the hydraulic oil drains, the accumulators 1c and 2c
The internal pressure of the hydraulic oil chambers 1e and 2e also drops.

Therefore, when raising the vehicle height to the standard vehicle height position again after draining the hydraulic oil to a certain extent in this way, the amount of oil required to extend the suspension unit bodies 1', 2' to a predetermined amount and the accumulator 1c must be adjusted. ，
The amount of oil required to compress the insides of the gas chambers 1f and 2f of the gas chambers 2c to a predetermined pressure must be fed from the hydraulic source 10.

As a result, the return operation time of the suspension units 1 and 2 becomes longer, so the oil pump needs to have a large capacity to compensate for the change in volume of the accumulators 1c and 2c. It was something that would end up happening.

In view of the conventional situation, the present invention has been developed to connect the hydraulic oil chamber of the suspension unit main body and the hydraulic oil chamber of the accumulator, and to connect the hydraulic pressure of the pressure oil supply passage and the hydraulic pressure of the drain passage of the suspension unit to both ends of the spool. These valves are operated by the mutual difference between these oil pressures, and are communicated through an on-off valve that is operated.The on-off valve is closed only when the suspension unit changes the vehicle height from the standard vehicle height position, and the vehicle height is adjusted accordingly. This eliminates the change in volume of the hydraulic oil chamber on the accumulator side at the time of change, so that even if the oil pump has a small capacity, the time required for the suspension unit to return to extension is not prolonged.

Embodiments of the present invention will be described in detail below with reference to the drawings.

That is, in the present invention, as illustrated in FIGS. 1 and 2, the hydraulic oil chambers 1d, 2d of the suspension unit bodies 1', 2', the accumulators 1c,
The hydraulic oil chambers 1e, 2e of the suspension units 1, 2 are communicated with the hydraulic oil chambers 1e, 2e of the suspension units 1, 2 through an on-off valve 20. When this happens, the valves are closed so that the capacities of the hydraulic oil chambers 1e and 2e of the accumulators 1c and 2c do not change.

As this on-off valve 20, a spool valve is used as shown in FIG. This spool valve 20
are the hydraulic oil chambers 1e of the accumulators 1c and 2c,
2e and a passage 2 that communicates with the hydraulic oil chambers 1d and 2d of the suspension units 1 and 2.
Oil chambers 26 and 27 are formed at both ends of the spool 23 and the end faces of the pistons 24 and 25, and the oil chamber 26 on the piston 24 side is connected to the pressure oil supply side of the suspension unit, that is, the first The first switching valve 4 shown in the figure is communicated with the pressure oil supply passage 3 downstream, and the hydraulic pressure of this pressure oil supply passage 3 is applied to one end side of the spool 23, while the oil chamber 27 on the piston 25 side is switched to the third switching valve. A set spring that communicates with the drain passage 6 upstream of the valve 7 and loads the oil chamber 27 with the hydraulic pressure of the drain passage 6 to bias the spool 23 toward one end on which the hydraulic pressure of the pressure oil supply passage 3 acts. It is loaded with 28 bullets.

Therefore, according to the present invention having such a configuration,
For example, under normal conditions, suspension units 1 and 2
Since the hydraulic pressure from the hydraulic source 10 is applied to the pressure oil supply side, the oil chamber 2 on the piston 24 side of the spool valve 20
While the supply pressure is acting on the spool 23, the third switching valve 7 is open on the drain side, so the oil chamber 27 on the piston 25 side of the spool valve 20 is at atmospheric pressure. The difference in hydraulic pressure acting on both ends is greater than the spring force of the set spring 28. Therefore, the spool 23 is moved to the second position by the internal pressure of the oil chamber 26 against the spring force of the set spring 28.
The hydraulic oil chambers 1 of the accumulators 1c and 2c are moved to the right as shown by the solid line in the figure, and the passages 21 and 22 are communicated with each other.
e, 2e and suspension unit body 1',
2' are connected to the hydraulic oil chambers 1d and 2d. As a result, the auto-leveling mechanism functions normally, and the accumulators 1c and 2c can function as gas springs when the vehicle is bounding.

When the vehicle shifts from this state to, for example, cornering, the full switching valves 4, 5, 7, and 9 are closed and the suspension units 1 and 2 are placed in the oil lock state, so the oil chamber 26 is still in the first switching state. Valve 4 and inlets 1a of units 1 and 2,
2a, while the oil chamber 27 side is at atmospheric pressure even though the third switching valve 7 is closed, so the spool valve 20 is in the open state. During cornering, rolling can be suppressed without inhibiting the gas spring action of the accumulators 1c and 2c.

Next, when the vehicle height is changed from the normal vehicle height position described above, for example, when lowering the vehicle height to the boarding/exiting position, the first and second switching valves 4 and 5 are closed as described above. In addition, in order to open the third and fourth switching valves 7 and 9, the pressure oil supply sides of the suspension units 1 and 2, and therefore the oil chamber 26 side of the spool valve 20, are at atmospheric pressure, and the oil at atmospheric pressure is The difference in oil pressure with the chamber 27 side becomes smaller than the spring force of the set spring 28. As a result, the spring force of the set spring 28 moves the spool 23 to the left as shown by the chain line in FIG. 2, and the piston 25 closes the passage 21. Therefore, communication between the hydraulic oil chambers 1e, 2e of the accumulators 1, 2 and the hydraulic oil chambers 1d, 2d of the suspension unit bodies 1', 2' is cut off, so that no oil is released from the suspension units 1, 2. Only the hydraulic oil in the hydraulic oil chambers 1d and 2d of the main bodies 1' and 2' is drained. Note that when the oil chamber 26 of the spool valve 20 is communicated with the supply passage 3 downstream of the check valves 14 and 15, the pressure on the oil chamber 26 side becomes equal to the set pressure of the relief valves 16 and 17; The mutual difference between the pressure and the atmospheric pressure on the oil chamber 27 side becomes smaller than the spring force of the set spring 28. Spool valve 20 similarly closes.

Furthermore, since the second switching valve 5 is also opened during oil draining, both oil chambers 26 and 2 of the spool valve 20 are opened at this time.
7 becomes atmospheric pressure, and in this case too, the spool valve 20 closes quickly to drain only the hydraulic oil in the hydraulic oil chambers 1d and 2d of the suspension unit bodies 1' and 2', and in both cases, the Muleta 1c,
There is no change in the volume of the hydraulic oil chambers 1e, 2e of 2c.

Therefore, in order to return the vehicle to the standard vehicle height position from such a state, it is only necessary to pump the amount of hydraulic oil necessary for the specified extension of the suspension unit bodies 1' and 2' from the hydraulic source 10, and the oil pump is then used. In other words, if an oil pump with a conventionally used capacity is used, the return operation time can be shortened accordingly.

In addition, when jacking up the vehicle as opposed to lowering the vehicle height as described above, pressure oil (same pressure as the inlet side) is also introduced from the drain side of the suspension units 1 and 2, so the spool valve 20 Both oil chambers 26 and 27 have the same internal pressure, and the spring force of the set spring 28 is greater than the difference in these oil pressures. As a result, the spool 23 is moved to the left in FIG. 2 by the spring force of the set spring 28 to close the valve, and in this case as well, the accumulators 1c and 2c
The volumes of the hydraulic oil chambers 1e and 2e are not changed.

Therefore, in order to return to the standard vehicle height from the jack up, it is only necessary to drain the predetermined reduced oil amount from the suspension unit bodies 1' and 2' since the internal pressure of the accumulators 1 and 2 has not increased. The recovery time can be greatly reduced.

As described above, according to the present invention, when changing the vehicle height based on the standard vehicle height posture, it is possible to avoid a change in the volume of the hydraulic oil chamber on the accumulator side of the suspension unit, so that the vehicle height posture is returned to the standard vehicle height posture again. In this case, the supply and discharge of hydraulic oil corresponding to the volume recovery of the accumulator-side hydraulic oil chamber is eliminated, and as a result, there is a practical effect that the return operation time can be significantly shortened. In addition, the on-off valve that provides such an effect is a spool valve, and its operation is performed by the hydraulic pressure of the pressure oil supply passage and the drain passage of the suspension unit. In addition to eliminating the need for manual opening/closing operations, it can be constructed at a lower cost than in the case of using the same.

[Brief explanation of the drawing]

FIG. 1 is a diagram of an operation control system for a hydroneumatic suspension, and FIG. 2 is a sectional view showing the main parts of the present invention. 1, 2...Suspension unit, 1',
2'...Suspension unit body, 1c, 2
c...Accumulator, 1d, 2d...Hydraulic oil chamber of suspension unit body, 1e, 2e...
... Hydraulic oil chamber of accumulator, 3 ... Pressure oil supply passage, 6 ... Drain passage, 20 ... Opening/closing valve, 2
3... Spool, 26, 27... Oil chamber, 28...
Set spring.

Claims (1)

[Claims] 1 In a hydroneumatic suspension installed between a suspension member of a vehicle and the vehicle body, the hydraulic fluid chambers 1d and 2d of the suspension unit body and the working chamber of the accumulator attached to the suspension unit body. 1e, 2
Insert the spool 23 into the outlet 1 of the suspension unit by directing the spool 23 between the spool 23 and
The inlets 1a, 2a and the outlets 1b, 2b of the suspension unit are communicated with each other through an on-off valve 20 which is biased by the hydraulic pressure of the drain passage 6 connected to the drain passages 6 and the spring force of the set spring 28 that carries the drain passage 6. The spool 23 of this on-off valve 20 is connected to the spool 23 of the on-off valve 20 by communicating both the inlet and the outlet with the pressure oil supply passage or the drain passage so that hydraulic oil can be supplied or discharged from both.
A hydropneumatic suspension characterized in that the opening/closing valve is closed when the mutual difference in oil pressure acting on both ends of the suspension becomes smaller than the spring force of a set spring 28.