JPH046562B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vehicle height adjustment device.

In recent years, regardless of the increase or decrease in the number of automobile passengers,
Installing a vehicle height adjustment device that always maintains the vehicle height at a constant height stabilizes the vehicle body posture and maintains the distance between the vehicle body and the road surface at an appropriate constant value. The taillights of the vehicle are lowered so that the headlights point upward during night driving to prevent blinding of other vehicles and improve safety.

2. Description of the Related Art Conventionally, there is a vehicle height adjusting device as shown in FIG. 1, for example. This device consists of suspension units 1 and 1' (for convenience, only the units for the front and rear wheels, which form a pair on the left and right sides, are shown in the drawing).
A shock absorber is provided with air chambers 2 and 2' in communication with each other, and the air pressure in these air chambers is automatically increased or decreased according to changes in vehicle height, and the vehicle height is always kept constant by the air pressure. A vehicle height sensor 3 that detects changes in vehicle height due to changes in the number of passengers, etc., a vehicle height control circuit 4 as a vehicle height control means, and air pressure for feeding into the air chambers 2 and 2'. The air pressure generating device 5 includes an air pressure generator 5 that generates air pressure, and an air pressure tank 6.

The air pressure generator 5 is composed of an air compressor (air pump) 8 driven by an electric motor 7, and the discharge side of the air compressor 8 is connected to a pipe 9.
The pneumatic tank 6 is connected via a dryer 10 and a check valve 11 to store air pressure in the pneumatic tank 6, and the pneumatic tank 6 is connected via a conduit 12 via an electromagnetic switching valve 13 for introducing air pressure. Connected to the air chamber 2, the solenoid of the switching valve 13 is connected to the vehicle height control circuit 4 via a conductor 14 in response to an input signal from the vehicle height sensor 3, which indicates that the vehicle height has become lower than the set value due to an increase in the number of passengers, etc. The switching valve 13 is switched to the pneumatic pressure introduction position by the signal input to the pneumatic tank 6, and pneumatic pressure is introduced into the air chambers 2, 2' to increase the pneumatic pressure in the air chambers 2, 2'. The vehicle height is then reset to the set value.

In addition, when the vehicle height becomes higher than the set position due to a decrease in the number of passengers, etc., in order to automatically return it to the set value, the check valve 11, the pneumatic tank 6, and the solenoid switching valve 13 for introducing pneumatic pressure are bypassed. A pneumatic discharge pipe 15 is connected between the pipes 9 and 12, a check valve 16 is provided in the pneumatic discharge pipe 15, and a pneumatic discharge electromagnetic switching valve 17 is provided in the discharge side pipe 9 of the air compressor 8. are connected by a conduit 18, and a signal outputted from the vehicle height control circuit 4 through a conductor 19 switches the switching valve 17 to the air pressure release position, thereby causing the air chambers 2,
The air pressure from 2' opens the check valve 16 and is discharged to the atmosphere from the switching valve 17 via the air pressure discharge line 15, thereby lowering the vehicle height to the set value.

20 is a pressure switch that detects the air pressure in the pneumatic tank 6;
The electric motor 7 is actuated by a drop in the air pressure inside the vehicle, inputs a signal to the vehicle height control circuit 4 via a conductor 21, and drives the electric motor 7 by a signal outputted from the vehicle height control circuit via a conductor 22. There is.

On the other hand, the weight distribution of a vehicle between the front and rear wheels changes depending on the number of passengers (carrying load), and the turning characteristics also change accordingly. For example, when one or two people are on board, the rear seats are empty, so the weight distribution is biased towards the front wheels, and four to two people are on board.
When five people are on board, they also sit in the rear seats, which increases the load on the rear wheels. Therefore, when 4 to 5 people are on board, compared to when 1 to 2 people are on board, the rear wheel load increases and the vehicle tends to oversteer. For this reason, if the suspension spring constant etc. are set to optimize the turning characteristics when 1 to 2 people are riding, the turning characteristics will tend to oversteer when 4 to 5 people are riding, and conversely, when 4 to 5 people are riding, the turning characteristics will tend to oversteer. If the suspension specifications are set to optimize the characteristics, the turning characteristics tend to understeer when one or two people are on board.

However, although the above-mentioned conventional vehicle height adjustment device functions to keep the vehicle height constant, it does not have the function to correct the turning characteristics that change due to changes in the axle load distribution between the front and rear wheels, so it cannot be adjusted under any loading conditions. However, it was not possible to obtain appropriate turning characteristics.

In the case of a suspension using the above-mentioned type of vehicle height adjustment device, the present invention provides that the vehicle height adjustment air chambers provided in the pair of left and right suspension units are communicated with each other, and that this communication can be adjusted. By focusing on the fact that the suspension roll rigidity on the front wheel side or the rear wheel side can be selectively adjusted or the suspension roll rigidity can be adjusted individually, a control valve that adjusts communication between the air chambers, and air pressure detection means for detecting the height of the air pressure of The control is based on a signal indicating the operation of a roll stiffness control means for varying the suspension roll stiffness on at least one side of the rear wheel and a switching valve for correcting a change in vehicle height, regardless of the output signal of the air pressure detection means. We provide a vehicle height adjustment device that is equipped with a vehicle height adjustment priority means that opens the valve, and this vehicle height adjustment device ensures the vehicle height adjustment function and always maintains an appropriate level under any loading conditions. In order to obtain turning characteristics,
This is an attempt to solve the above problem.

Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 2 shows an embodiment of the present invention, in which the same parts as in FIG. 1 are designated by the same reference numerals. However, in this example, the suspension units 1 and 1' are respectively suspension units for the two rear wheels.

In the present invention, a control valve 24 for adjusting the degree of communication is provided in the communication passage 23 that communicates between the air chambers 2 and 2' provided in the shock absorbers of the rear two-wheel suspension units 1 and 1'. This control valve 24 is a normally closed electromagnetic on-off valve, and its solenoid 2
4a is connected from a roll stiffness control circuit 25 as a roll stiffness control means and a vehicle height adjustment priority means to an electric line 26.
The communicating path 23 is opened and closed by being turned on and off by a signal supplied through the .

A pressure switch 27 as air pressure detection means is connected to the communication path 23, and on/off signals from the pressure switch are supplied to the roll rigidity control circuit 25 through an electric line 28. Switching valve control signals from the electric lines 14 and 19 are also input to the roll stiffness control circuit 25, and the roll stiffness control circuit 25 turns on and off the solenoid 24a based on the above input signals.

The roll stiffness control circuit 25 includes, for example, an averaging circuit 29, an OR gate 30, and a drive circuit 31, as shown in FIG. The averaging circuit 29 averages the on/off signals of the pressure switch 27. When the air pressure in the air chambers 2, 2' frequently fluctuates due to bounces from the road surface while the wheels are running, the pressure switch 27 This is provided to prevent the roll control circuit 25 from operating frequently. This averaging circuit 29
The output is supplied to the OR gate 30 together with the signals from the electric lines 14 and 19, and the OR gate 30 takes the logical sum of these input signals and energizes the control valve solenoid 24a via the drive circuit 31 as appropriate.

The operation of the vehicle height adjusting device of the present invention having the above-mentioned structure will be explained next.

When the live load is small, the rear wheel load is low, and therefore the air pressure determined by the rear wheel load in the air chambers 2, 2' relating to the two rear wheels is also low. At this time, pressure switch 2
7 is open and cannot supply an H level signal to the OR gate 30. By the way, if at this time the vehicle height control circuit 4 is supplying the H level signal to the switching valve 13 or 17 during the aforementioned vehicle height adjustment operation, the H level signal is supplied to the drive circuit 31 via the OR gate 30. , the solenoid 24a via this drive circuit.
As a result of being energized, the control valve 24 opens, and air pressure can be supplied to and discharged from both air chambers 2, 2', and the vehicle height adjustment function can be performed as described above. When this vehicle height adjustment is completed and the above-mentioned H level signals on the electric lines 14 and 19 disappear, the OR gate 30
cannot output an H level signal, and the control valve 24 is closed. As a result, the communication path 23 is blocked and the communication between the air chambers 2 and 2' is cut off.
2' acts as an independent air spring, and the suspension roll rigidity on the rear wheel side increases accordingly. The suspension roll rigidity is greater than the suspension roll rigidity on the front wheel side.

Thus, when the carrying load is small, the turning characteristics tend to understeer as described above, but this tendency can be weakened and the turning characteristics can be corrected to be appropriate. If this correction becomes excessive, the control valve 24 may not completely close the communication passage 23 in its closed state, but may limit the degree of communication, or the virtual An orifice 32 may also be provided in parallel to the control valve 24 as shown by the lines.

On the other hand, if the laminated load is heavy and the rear wheel load increases significantly, the air pressure in the air chambers 2, 2' increases as the rear wheel load increases and closes the pressure switch 27.
At this time, the pressure switch 27 supplies an H level signal to the OR gate 30, and this H level signal
As a result of being supplied to the drive circuit 31 through the gate, the control valve 24 is opened by energizing the solenoid 24a. Therefore, the air chambers 2 and 2' are communicated with each other, and the suspension roll rigidity on the rear wheel side is lowered and becomes smaller than the suspension roll rigidity on the front wheel side.

Thus, when the carrying load is large, the turning characteristics tend to oversteer as described above, but this tendency can be weakened and the turning characteristics can be corrected to be appropriate.

As mentioned above, in order to vary the suspension roll rigidity between the front and rear wheels depending on the load, the air chambers 2, 2' of the rear wheel suspension units 1, 1' are adjusted as in the above embodiment. Instead of communicating and blocking, the purpose can be achieved by communicating and blocking the air chambers 34 and 34' of the front wheel suspension units 33 and 33' as shown in Fig. 4, or by combining the two. .

In the former example, as shown in FIG.
The control valve 24' to be inserted into the communication path 35 between 4 and 34' is a normally open electromagnetic on-off valve, and the solenoid 24'a is a roll stiffness control circuit as a roll stiffness control means and vehicle height adjustment priority means. 25 performs on/off control via an electric line 26. The roll stiffness control circuit 25' is supplied with a signal from the pressure switch 27' connected to the communication path 35 via the electric line 28', and also receives switching valve signals from the electric lines 14 and 19. As shown in FIG. 5, it consists of an averaging circuit 36, an OR gate 37, a NAND gate 38, an AND gate 39, and a drive circuit 40, which function similarly to the circuit 29 in the example described above.

In the device of this example having such a configuration, during the vehicle height adjustment when an H level signal is output to either the electric line 14 or 19, the OR operation is performed to calculate the logical sum of the signals.
Gate 37 supplies an H level signal to one input terminal of NAND gate 38. Here, when the pressure switch 27' that responds to the heavy load is closed, an H level signal is supplied from this pressure switch to the other input terminal of the NAND gate 38, and the NAND gate 38 converts the L level signal into an AND gate. Supply to 39. When the load is light and the pressure switch 27' is open, an L level signal is supplied from the pressure switch to the AND gate 39. Therefore, during vehicle height adjustment, the AND gate 39 cannot output an H level signal regardless of the signal level from the pressure switch 27', that is, regardless of the stacked load, and the solenoid 24'a is kept in the deenergized state. .
As a result, the control valve 24' is opened and the air chamber 34,
34' are communicated with each other so that the vehicle height adjustment is not hindered.

On the other hand, when the vehicle height adjustment is completed and no H level signal is output to either of the electric lines 14 or 19, the OR
Gate 37 cannot supply an H level signal to NAND gate 38, and this NAND gate 38 supplies an H level signal to AND gate 39. Therefore, the output signal level of AND gate 39 is determined by the signal level from pressure switch 27'.
When the load is heavy and the pressure switch 27' is closed to supply an H level signal to the AND gate 39, this AND gate supplies an H level signal to the drive circuit 40, which passes through the solenoid 24'. energize a. As a result, the control valve 24' closes, cutting off the communication between the air chambers 34, 34', producing an air spring action in each air chamber 34, 34', and increasing the suspension roll rigidity on the front wheel side accordingly. The relative suspension roll rigidity between the front and rear wheels can be made different, for example, the suspension roll rigidity can be made larger than the suspension roll rigidity on the rear wheel side.

Therefore, when the carrying load is heavy, the turning characteristics tend to oversteer as described above.
This tendency can be weakened and the turning characteristics can be corrected to be appropriate. In addition, if this correction becomes excessive, the communication between the air chambers 34, 34' is not completely cut off, but only limited, even when the control valve 24' is closed, as shown in FIG. An orifice 32' may also be provided in parallel to the control valve 24' as shown in phantom.

On the other hand, if the load is light, pressure switch 2
7' opens and supplies an L level signal to the AND gate 39, so that the AND gate 39 cannot output an H level signal and the solenoid 24'a is deenergized. Therefore, the control valve 24' is opened and the air chambers 34,
34', thereby making it possible to make the suspension roll rigidity on the front wheel side smaller than that on the rear wheel side.

Thus, when the carrying load is light, the turning characteristics tend to understeer as described above, but this tendency can be weakened and the turning characteristics can be corrected to be appropriate. In addition, although the above-mentioned embodiment shows an example in which the control valves 24, 24' are provided on either the front wheel side or the rear wheel side, it is also possible to provide control valves on both the front and rear wheels to make the roll stiffness different. It is also possible to increase the effect of varying roll stiffness.

Thus, the vehicle height adjustment device of the present invention has, for example, the configuration of the two examples described above, and the vehicle height adjustment air chambers 2, 2' (34) provided in the pair of left and right suspension units 1, 1' (33, 33'), respectively. . By operating the control valve according to the air pressure of
A roll stiffness control device path 25 (25') as a vehicle height adjustment priority means is configured to preferentially open the switching valve that supplies and discharges air pressure to and from the air chamber during vehicle height change correction operation. In addition to the original vehicle height adjustment function, it is also possible to individually adjust the suspension roll stiffness of at least one of the front wheels or the rear wheels. It can be corrected to an appropriate value, and safety during cornering can be improved.

[Brief explanation of drawings]

Figure 1 is a system diagram showing a conventional vehicle height adjustment device, Figure 2 is a system diagram showing an example of the vehicle height adjustment device of the present invention, Figure 3 is a roll stiffness control circuit diagram of the same device, and Figure 4 is a system diagram of the present invention. FIG. 5 is a system diagram showing another example of the invention vehicle height adjustment device, and FIG. 5 is a roll rigidity control circuit diagram of the same device. 1, 1', 33, 33'... Suspension unit, 2, 2', 34, 34'... Air chamber, 3...
Vehicle height sensor, 4...Vehicle height control circuit, 5...Pneumatic pressure generator, 6...Pneumatic tank, 11, 16...Check valve, 13...Air supply electromagnetic switching valve, 17...
...Air pressure release electromagnetic switching valve, 23, 35...Air chamber communication passage, 24, 24'...Control valve, 25, 25'...
... Roll rigidity control circuit, 27, 27'... Pressure switch, 32, 32'... Orifice.

Claims (1)

[Scope of Claims] 1. An air chamber provided in a pair of left and right suspension units and communicated with each other; a switching valve that supplies and discharges air pressure to and from the air chamber; A vehicle height adjustment device comprising: a vehicle height control means for correcting changes in vehicle height by operating the switching valve; a control valve for controlling communication between the air chambers; air pressure detection means for detecting the height of the air pressure; and based on a signal indicating the height of the air pressure outputted by the air pressure detection means, the control valve is actuated to detect at least one of the front wheels or the rear wheels depending on the vehicle loading condition. On the other hand, the control valve is kept in an open state regardless of the output signal of the air pressure detection means based on a signal indicating the operation of the roll stiffness control means that varies suspension roll stiffness and the switching valve that corrects changes in vehicle height. A vehicle height adjustment device comprising: a vehicle height adjustment priority means for controlling the vehicle height; 2. The roll stiffness control means controls the air in the suspension unit for the rear wheels so that the suspension roll stiffness on the rear wheel side is lower than the suspension roll stiffness on the front wheel side when the vehicle load is heavy compared to when it is light. 2. The vehicle height adjustment device according to claim 1, wherein the control valve for controlling communication between chambers is operated in a direction to open the control valve. 3. The roll stiffness control means adjusts the air chamber of the front wheel suspension unit so that the suspension roll stiffness on the front wheel side is higher than the suspension roll stiffness on the rear wheel side when the vehicle load is heavy compared to when it is light. 2. The vehicle height adjustment device according to claim 1, wherein the control valve for adjusting the communication between the two is operated in a closing direction.