JPH0470161B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a vehicle height adjustment device that can adjust vehicle height in three stages: "high,""medium," and "low," and determines whether the vehicle is driving on a rough road using a vehicle height sensor or an acceleration sensor. The present invention relates to a suspension device for a vehicle that sets a target vehicle height to a high value when a rough road is detected, and suspends vehicle height adjustment for a set time after the rough road determination is canceled.

Conventionally, when driving on rough roads, the purpose of raising the vehicle height is to increase the vehicle's minimum ground clearance, reduce contact between the road surface and the vehicle body, improve drivability on rough roads, and reduce damage to the vehicle body. A vehicle height control device is known. When the rough road judgment is made every set time (for example, 2 seconds), depending on the condition of the rough road, the judgment that the road is bad and the judgment that the road is good may alternate. The vehicle height is repeatedly adjusted to raise the vehicle height for a high vehicle height, and to lower the vehicle height for a medium-high vehicle. The consumption increases and the frequency of compressor operation increases, which increases the consumption of battery power, and if a lamp is provided to indicate that the vehicle height is being adjusted, the lamp turns on and off repeatedly, reducing the reliability of the system. There is a problem.

This invention was made in view of the above points,
The purpose of this is to use a vehicle height control device that can control vehicle height in three stages: "high,""medium," and "low." To provide a suspension device for a vehicle capable of preventing an increase in consumption of battery power by setting a vehicle height to high and suspending vehicle height adjustment for a set time after a bad road judgment is canceled.

An embodiment of this invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of a car equipped with this device. As shown in Fig. 1, front air suspension units are installed between the left and right ends of the front wheel FA side axle and the vehicle body B side member.
FS, FS1, FS2 are installed, and the rear wheel
Rear air suspension units are installed between the left and right ends of the BA side axle and the vehicle body B side members.
RS, RS1, and RS2 are interposed.

These air suspension units FS ₁ , FS
2, RS1, and RS2 have almost the same structure, so unless the front and rear suspension units are specifically explained, the air suspension units will be referred to by reference numerals as shown in Figure 2. The explanation will be made using S, and only the parts necessary for vehicle height control will be illustrated and explained.

That is, these air suspension units S incorporate a strut type damping force switching type shock absorber 1, and this shock absorber 1 has a cylinder attached to the front wheel FA side or the rear wheel BA side, and this The cylinder is equipped with a piston that is slidably inserted into the cylinder, and the cylinder moves up and down with respect to the piston rod 2 in accordance with the up and down movement of the wheel, thereby creating a shock absorber 1.
It has a damping function depending on the position of the shutter inside, allowing it to absorb shock effectively.

Incidentally, a main air spring chamber 3 which also serves as a vehicle height adjustment fluid chamber is disposed coaxially with the piston rod 2 at the top of the shock absorber 1.
Since a part of the main air spring chamber 3 is formed by a bellows 4, the piston rod 2 can be moved up and down by supplying and discharging air to the main air spring chamber 3.

Further, a sub air spring chamber 5 is disposed coaxially with the piston rod 2 directly above the main air spring chamber 3.

Further, the outer wall of the shock absorber 1 is provided with a spring receiver 6a facing upward, and the outer wall of the auxiliary air spring chamber 5 is provided with a spring receiver 6b facing downward. A coil spring 7 is loaded between 6b.

Further, these air spring chambers 3 and 5 are connected to each other via a communication passage 9 bored in a control rod 8 which is rotatably inserted into the piston rod 2. An on-off valve 10 constituting a spring constant switching mechanism is interposed therein.

The on-off valve 10 includes a first valve part 10a that cuts off communication between the auxiliary air spring chamber 5 and the communication passage 9, and a second valve part 10a that cuts off communication between the main air spring chamber 3 and the communication passage 9.
The valve portion 10b is configured to include a valve portion 10b.

Therefore, when the on-off valve 10 is in the open mode,
The main air spring chamber 3 and the auxiliary air spring chamber 5 can be brought into communication with each other to make the spring constant small (soft). By cutting off the chamber 5, the spring constant can be increased (hardened).

That is, by rotating the control rod 8, the on-off valve 10 can be opened and closed.
By opening and closing, the spring chamber capacity can be changed.

By changing this spring chamber capacity, the spring constant of the suspension can be changed.

Further, the lower end of the control rod 8 is provided with a control valve 8a that can change the orifice area of the piston 1a of the shock absorber 1. This control valve 8a is configured by the control rod 8 to increase the orifice area of the piston 1a to reduce the damping force when the on-off valve 10 is in the open mode, and to reduce the damping force when the on-off valve 10 is in the closed mode.
The damping force is increased by reducing the orifice area.

Thus, the vehicle height adjustment of the automobile is carried out by the configuration shown in FIG. That is, as shown in FIG. 2, compressed air for adjusting the vehicle height is transmitted from a compressor 11 as a compressed air generating device to a dryer 12,
Each suspension unit is It is now supplied to S.

The compressor 11 compresses the air sent from the air cleaner 18 and supplies the compressed air to the dryer 12. The compressed air dried by silica gel or the like in the dryer 12 is shown by the solid line arrows in FIG. Like, suspension unit S
supplied to Furthermore, when compressed air is exhausted from the suspension unit S, the exhaust solenoid valve 1 is
Via 9, the compressed air is released to the atmosphere.

Note that the dryer 12 includes a reserve tank 20.
A portion of the compressed air is supplied from this reserve tank 20 to each suspension unit S via an air supply solenoid valve 21.

Further, as shown in FIG. 2, a vehicle height sensor 22 is provided, and this vehicle height sensor 22 is attached to a lower arm 23 of the front right suspension of the vehicle to detect the front vehicle height of the vehicle. The vehicle height sensor 22F includes a height sensor 22F and a rear vehicle height sensor 22R that is attached to the lateral rod 24 of the rear left suspension of the vehicle and detects the rear vehicle height of the vehicle.
A front vehicle height detection signal and a rear vehicle height detection signal are supplied from 2F and 22R to a control unit 25 serving as a vehicle height adjustment control section.

Each sensor 22F, 22 in the vehicle height sensor 22
R is the Hall IC element and one of the magnets connected to the wheel FA.
and the other side is attached to the vehicle body B side to detect the distance from the normal vehicle height level and the low vehicle height or high vehicle height level, respectively. Note that the vehicle height sensor may be of any other type, for example, one using a phototransistor.

Furthermore, the speedometer 26 has a built-in vehicle speed sensor 27, which detects the vehicle speed and sends a detection signal to the control unit 2.
Mechanical speedometers use a reed switch type vehicle speed sensor, and electronic speedometers use a transistor-based open collector output type sensor.

Further, an acceleration sensor 28 is provided as a vehicle body posture sensor that detects changes in the posture of the vehicle body.
This acceleration sensor 28 is designed to detect changes in the vehicle body posture such as pitch, roll, and yaw on the car's springs. For example, when there is no acceleration, the weight is in a hanging state, and the light from the light emitting diode is directed toward the shielding plate. The structure is such that the absence of acceleration can be detected by blocking the light from reaching the photodiode.

When acceleration acts in the front and back, left and right, or up and down directions, the weight tilts or moves, and the acceleration state of the vehicle body is detected.

Since the acceleration sensor 28 is provided on a spring, the acceleration sensor 28 and the control unit 2
5, the harness that connects the 5 is not affected by the stroke of the suspension and will not be bent or displaced. Further, the waterproof/dustproof treatment applied to the acceleration sensor 28 can also be simplified.

A steering sensor 32 detects the rotational speed of the steering wheel 33, that is, the steering speed.
4 is an accelerator sensor (not shown) that detects the operating speed of the accelerator pedal of the engine; 35 is a pneumatic drive mechanism that is connected to the reserve tank 20 via a three-way switching valve 36 and rotates the control rod 8; The direction switching valve 36 is located at a position where the pneumatic drive mechanism 35 and the reserve tank 20 are communicated with each other by a signal from the control unit 25;
Either one of the positions communicating the pneumatic drive mechanism 35 and the atmosphere can be selected, and this has the function of rotating the control rod 3 in the opposite direction to a predetermined position and shifting from the soft state to the hard state. . Note that instead of the pneumatic drive mechanism 35, a solenoid drive mechanism may be used. In addition, the code LF indicates the engine room (dashed line)
LR indicates the boundary between the passenger compartment and the trunk (to the right of the broken line LR). Moreover, the code 30 is
This figure shows a bump stopper for preventing damage to the wall surface of the main air spring chamber 3 due to the relative rise of the cylinder of the shock absorber 1 on rough roads. Reference numeral 31 is a mode selection switch serving as a high vehicle height selection switch. By the way, this mode selection switch 31 is an auto mode in which the vehicle height is automatically controlled to normal vehicle height or low vehicle height, that is, "medium" vehicle height or "low" vehicle height is set as the target vehicle height. It is possible to switch between a high mode in which the vehicle height is controlled to a high vehicle height, that is, a "high" vehicle height is set as the target vehicle height.

Next, the operation of an embodiment of the present invention configured as described above will be described. First, the overall operation will be explained using the flowchart shown in FIG. First, in step S1, the vehicle height is initially set to an auto mode in which the vehicle height is automatically adjusted to a "medium" or "low" vehicle height. Then, the normal, ie, "medium" vehicle height is set as the target vehicle height. Next, in step S2, the fourth
It is determined whether or not the road surface on which the vehicle is traveling is a rough road, which will be described in detail later using figures.
Then, in step S3, a target vehicle height determination, which will be described in detail later with reference to FIG. 5, is performed, that is, it is determined to what level the target vehicle height should be set. That is, if the high mode is selected by the mode selection switch 31, the "high" vehicle height is set as the target vehicle height, and if it is determined that the road is on a rough road as described above, the "high" vehicle height is also set as the target vehicle height. Set high. The process then proceeds to step S4, where vehicle height signals are read into the control unit 25 from the vehicle height sensors 22F and 22R. Then, in step S5, it is determined whether the vehicle height detected by the vehicle height sensors 22F and 22R is equal to the estimated vehicle height set in step S3. If the determination in step S5 is "NO", the process proceeds to step S6 and vehicle height adjustment is started toward the target vehicle height. For example, if the vehicle height detected in step S4 is lower than the target vehicle height, the vehicle height is raised by supplying air to the main air spring chamber 3 of each suspension unit. On the other hand, if the vehicle height detected in step S4 is higher than the target vehicle height, air is exhausted from the main air spring chamber 3 of each suspension unit. Then, the process returns to step S2, and when the vehicle height becomes equal to the target vehicle height in step S5, the process proceeds to step S7.
Then, the vehicle height adjustment in step S6 is completed.

Next, refer to the flowchart in Figure 4 and proceed to the third step.
The rough road judgment performed in step S2 in the figure will be explained in detail. First, in step S10, it is determined whether the vehicle speed is 40 km/h or more, and if the determination is ``YES'', the control unit 25 reads the time of the 2-second timer for counting 2 seconds in step S11. Then, in step S12, it is determined whether two seconds have been counted by the two second timer. If the determination in step S12 is "NO", the process advances to step S13 and the vehicle height sensor 2 is checked.
2F, 22R output signal control unit 2
5, and proceed to step S14 to calculate the acceleration (G).
The output signal of the sensor 28 is sent to the control unit 2.
5. Then, the process advances to step S15 and the rough road determination is canceled. This is done, for example, by resetting a rough road flag in the memory area of the control unit 25 that is set when the vehicle travels on a rough road. Thereafter, when 2 seconds have been counted by the 2 second timer, a determination of ``YES'' is made in step S12, and the process proceeds to step S16. In this step S16, the two second timer is reset. Then, the process proceeds to step S17, and from the vehicle height sensor 22F (22R) detected in step S13,
It is determined whether the HH code, that is, the vehicle height higher than the high vehicle height level has been output two or more times. If the determination in step S17 is ``YES'', the process advances to step S18. In step S18, the vehicle height sensors 22F and 22 detected in step S13 are
It is determined whether the R to LL code, that is, the vehicle height lower than the low vehicle height level has been output two or more times. If the determination in step S18 is ``YES'', the process advances to step S19 and the rough road determination is established. This is done by setting the rough road flag. On the other hand, step S17 or S18 above
If the determination is "NO" in step S20, it is determined whether the output signal of the acceleration (G) sensor 28 has been turned on two or more times. In other words, it is determined whether the output of the acceleration (G) sensor 28 has passed through a state of low acceleration and high acceleration two or more times within two seconds. If ``YES'' is determined in this step S20, the process proceeds to step S21, where it is determined whether the output signal of the acceleration (G) sensor 28 has been turned on twice or more during the previous two seconds. If the determination in step S21 is ``YES'', the process proceeds to step S19, where the rough road determination is established, and if the determination in step S21 is ``NO'', the process proceeds to step S15, where the rough road determination is canceled. . In this way, the vehicle height sensor 22F, 22R or the acceleration (G) sensor 28
A rough road judgment is made based on the output signal.

Incidentally, since the acceleration acting on the acceleration sensor 28 on a rough road is basically the same whether the vehicle height is standard or high, the rough road can be reliably detected.

Next, referring to FIG. 5, proceed to step S3 in FIG.
The target vehicle height determination carried out will be explained in detail. First, in step S31, it is determined whether or not the rough road determination is established. If the determination in step S31 is ``YES'', the process advances to step S32 and the target vehicle height is set to high (HIGH). On the other hand, if the determination in step S31 is "NO", the process proceeds to step S33, where it is determined whether or not the rough road determination has been cleared after the determination has been made. If the determination in step S33 is ``YES'', the process advances to step S34, where it is determined whether 12 seconds have elapsed since the rough road determination was canceled. "NO" in this step S34
If it is determined that this is the case, the process proceeds to step S35, where the vehicle height adjustment is put on hold, that is, the air supply and exhaust to each suspension unit is stopped. On the other hand, if the determination in step S34 is YES, the process advances to step S36, where the suspension of the vehicle height adjustment made in step S35 is released, and the process advances to step S37, where the mode selection switch 31 selects AUTO. It is determined whether the mode is selected. This step S37
If the determination is ``YES'' in step S38, it is determined whether the target vehicle height is set to normal (medium). If the determination in step S38 is "NO", the process proceeds to step S39, where it is determined whether the vehicle speed detected by the vehicle speed sensor 27 is 70 km/h or less. "NO" in this step S39
If it is determined that this is the case, the process advances to step S40 and the target vehicle height is set to "low".

On the other hand, if the determination in step S38 is ``YES'', the process proceeds to step S41, where it is determined whether the vehicle speed detected by the vehicle speed sensor 27 is 90 km/h or more. If the determination in step S41 is ``YES'', it is determined in step S42 whether or not the vehicle speed has been 90 km/h or higher for 10 seconds. If the determination in step S42 is ``YES'', the process proceeds to step S40, where the target vehicle height is set to low. In other words, even if the target vehicle height is normal,
When the vehicle speed exceeds 90 km/h for 10 seconds, the target vehicle height is set to low to ensure driving stability.
On the other hand, if the determination in step S41 is "NO", the process proceeds to step S43, where the target vehicle height is set to normal (middle).

By the way, if "NO" is selected in step S37 above,
That is, if it is determined that the high vehicle height selection mode is selected, the process proceeds to step S44, where it is determined whether the target vehicle height is set to a high level. If it is determined as "YES" in this step S44, the step
Proceeding to S45, it is determined whether the vehicle speed is 70 km/h or more. If the determination in step S41 is "NO", the process advances to step S32. On the other hand, if the determination in step S45 is ``YES'', the process proceeds to step S46 and waits until the vehicle speed reaches 70km/h or higher.
It is determined whether 10 seconds have elapsed. This step
If the determination is "NO" in S46, the process proceeds to step S32, and the determination is "YES" in step S46.
If it is determined that this is the case, the process advances to step S43.

On the other hand, if the determination in step S44 is "NO", the process proceeds to step S47, where it is determined whether the target vehicle height is at the normal (middle) level. If the determination in step S47 is ``YES'', the process proceeds to step S48, where it is determined whether the vehicle speed is 50 km/h or less. If the determination in step S48 is ``YES'', the process advances to step S32. On the other hand, if the determination in steps S47 and S48 is "NO", the process advances to step S38. In this way, vehicle height adjustment is suspended for 12 seconds after the bad road judgment is canceled.

As detailed above, according to this invention, "high"
In a vehicle height control device that can perform vehicle height control in three stages: "medium" and "low," it is determined that the vehicle is traveling on a rough road using a vehicle height sensor or an acceleration sensor that detects acceleration acting on the vehicle body as a sprung mass. In this case, the target vehicle height is set high, and after the bad road judgment is canceled, the vehicle height adjustment is put on hold for a set period of time, so the judgment that the road is bad and the road is good alternates. It is possible to prevent the battery power consumption from increasing due to repeated vehicle height raising adjustments and vehicle height lowering adjustments being repeated alternately.

In addition, when a judgment is made that the road is rough, the target vehicle height is set to a high vehicle height and vehicle height raising control is performed, and when the rough road judgment is canceled, the vehicle height has reached the high vehicle height. Even if the vehicle height adjustment is not performed, the vehicle height adjustment is suspended at that point, so it is possible to eliminate wasteful air consumption caused by continuing vehicle height raising control from that point on.

Further, according to the present invention, since the acceleration sensor detects acceleration acting on the sprung vehicle body, the acceleration sensor can be attached to the vehicle body. Therefore, the harness that connects the acceleration sensor and the controller is not related to the stroke of the suspension and does not undergo bending displacement, making waterproofing and dustproofing much simpler.

Furthermore, on rough roads, the acceleration acting on the vehicle body is basically the same whether the vehicle height is standard or high, so rough roads can be detected reliably. Moreover, when the road changes from a good road to a bad road, the acceleration generated on the sprung body of the vehicle often lags behind the vertical acceleration generated on the unsprung part. Since the vehicle is configured to determine whether the road is rough, there is no problem of a delay in determining whether the road is rough.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of a car equipped with this device, Figure 2 is an overall configuration diagram of this device, and Figures 3 to 5
The figure is a flowchart for explaining the operation of one embodiment. 11...Compressor, 25...Control unit, 27...Vehicle speed sensor, 31...Mode selection switch.

Claims (1)

[Scope of Claims] 1. A hydraulic suspension unit that is interposed between a wheel side member and a vehicle body side member and has a fluid chamber for adjusting vehicle height, a vehicle height sensor that detects vehicle height, and a spring. A vehicle height detection signal obtained by an acceleration sensor that detects acceleration acting on the vehicle body and the vehicle height sensor is compared with a set target vehicle height, and the vehicle height is displaced to the target vehicle height. and a control device having vehicle height adjustment means for controlling the supply and discharge of fluid to the vehicle height adjustment fluid chamber to adjust the vehicle height, and the control device is configured to adjust the vehicle height within a set time using the vehicle height sensor. When the first condition is satisfied, in which the vehicle height is detected more than a set number of times when the vehicle height exceeds the set range, or the second condition is satisfied, in which the acceleration sensor detects a change in acceleration exceeding the set value more than the set number of times within a set time. Sometimes it is determined that the road is bad,
a rough road determining means for canceling the determination that the road is on a rough road when neither the first condition nor the second condition is satisfied by the vehicle height sensor and the acceleration sensor; When the determination means does not determine that the road is bad, the normal vehicle height is set as the target vehicle height, and when the rough road determination means determines that the road is rough, the target vehicle height is set. and target vehicle height setting means for setting a high vehicle height higher than the normal vehicle height, and further, the control device further comprises a target vehicle height setting means for setting a high vehicle height higher than the normal vehicle height; a rough road release detection means for detecting that the judgment that the road is on a bad road has been canceled; A suspension device for a vehicle, further comprising vehicle height adjustment holding means for stopping fluid supply and discharge by the vehicle height adjustment means.