JPH0645288B2 - Vehicle suspension system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a vehicle height control device capable of performing vehicle height control in three stages of “high”, “medium”, and “low”, and determines that the vehicle is traveling on a rough road by a vehicle height sensor or an acceleration sensor. The vehicle suspension device is configured to cancel the bad road determination after being performed when the road is determined to be a good road for a set time or more.

Conventionally, when traveling on a rough road, the vehicle height is increased to raise the ground minimum height of the vehicle to reduce the contact between the road surface and the vehicle body to improve the running performance on the rough road and reduce the damage to the vehicle body. There is known a vehicle height control device. A certain set time (for example, 2 seconds) for determining a rough road for determining such a rough road traveling
Depending on the condition of the bad road, the judgment that it is a bad road and the judgment that it is a good road are repeated alternately, and the vehicle height increase adjustment for high vehicle height and medium vehicle height Not only is the vehicle height adjustment not repeated smoothly until the vehicle height becomes high, but the air consumption also increases, the frequency of compressor operation increases, and the consumption of battery power increases. Alternatively, when a lamp indicating that the vehicle height is being adjusted is provided, there is a problem that the lamp is repeatedly turned on and off to reduce the reliability of the system.

The present invention has been made in view of the above points, and an object thereof is to provide a vehicle height control device capable of performing vehicle height control in three stages of "high", "medium", and "low" by using a vehicle height sensor or an acceleration sensor. After it is judged that the vehicle is running, the bad road judgment is canceled when the road is judged to be a good road for more than the set time, so that the consumption of battery power can be prevented from increasing. To provide a device.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view of an automobile equipped with this device.

As shown in FIG. 1, front air suspension units FS (FS1, FS2) are respectively provided between the left and right end portions of the front wheel FA side axle and the vehicle body B side member, and the rear wheel BA side. The rear air suspension unit RS is installed between the left and right ends of the axle and the body B side member.
(RS1, RS2) are installed.

These air suspension units FS1, FS2, RS1
, RS2 have almost the same structure,
The air suspension unit will be described with reference numeral S as shown in FIG. 2 and only the portion necessary for vehicle height control will be described, except for the case where the front and the rear are specifically distinguished. Show and explain.

That is, these air suspension unit S
The shock absorber 1 of the strat type damping force switching type is incorporated, and the shock absorber 1 has a front wheel F.
The shock absorber is provided with a cylinder mounted on the A side or the rear wheel BA side and a piston slidably fitted in 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. 1
The damping function according to the position of the inner shutter is exhibited, and the shock can be effectively absorbed.

By the way, a main air spring chamber 3 which also functions as a vehicle height adjusting actuator is disposed above the shock absorber 1 coaxially with the piston rod 2, and a part of the main air spring chamber 3 is a bellows 4. Since it is formed, it is possible to allow the piston rod 2 to move up and down by supplying and discharging air to and from the main air spring chamber 3.

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

Further, the outer wall portion of the shock absorber 1 is provided with a spring receiver 6a directed upward, and the outer wall portion of the sub air spring chamber 5 is formed with a spring receiver 6b directed downward. , 6b, a coil spring 7 is loaded.

Further, these air spring chambers 3 and 5 are connected to each other through a communication passage 9 formed in a control rod 8 rotatably inserted in the piston rod 2.
An on-off valve 1 that constitutes a spring constant switching mechanism is provided in this communication passage 9.
0 is installed.

The on-off valve 10 includes a first valve portion 1a for disconnecting communication between the sub air spring chamber 5 and the communication passage 9 and a second valve portion 10b for disconnecting communication between the main air spring chamber 3 and the communication passage 9. It is made up of:

Therefore, when the on-off valve 10 is in the open mode, the main air spring chamber 3 and the sub air spring chamber 5 can be in communication with each other to reduce the spring constant (softly), and the on-off valve 10 is closed. In the mode, the main air spring chamber 3 and the sub air spring chamber 5 are shut off to increase the spring constant (harden).

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

The spring constant of the suspension can be changed by changing the capacity of the spring chamber.

Further, a control valve 8a capable of changing the orifice area of the piston 1a of the shock absorber 1 is provided at the lower end of the control rod 8. This control valve 8
a is a control rod 8 which reduces the damping force by increasing the orifice area of the piston 1a when the on-off valve 10 is in the open mode, and reduces the orifice area of the piston 1a when the on-off valve 10 is in the closed mode. It is configured to increase the damping force.

Thus, the vehicle height adjustment of the automobile is performed by the configuration shown in FIG. That is, the compressed air for adjusting the vehicle height is the second
As shown in the figure, a compressor 11 as a compressed air generator, a dryer 12, a joint 13, a rear solenoid valve 14, a front solenoid valve 15 and a pipe 16 for connecting them respectively and a part of a pipe-shaped control rod are connected to each other. It is adapted to be supplied to each suspension unit S via the connection port 17 which is communicated with the passage 9.

The compressor 11 compresses the air sent from the air cleaner 18 and supplies the compressed air to the dryer 12, and the compressed air dried by silica gel or the like of the dryer 12 is indicated by each solid line arrow in FIG. As described above, it is supplied to the suspension unit S. When the compressed air is exhausted from the suspension unit S, the second
Exhaust solenoid valve 1
The compressed air is released to the atmosphere side via 9.

A reserve tank 20 is connected to the dryer 12, and a part of the compressed air is supplied from the 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. A high sensor 22F and a rear vehicle height sensor 22 mounted on a lateral rod 24 of the rear left suspension of the vehicle to detect the rear vehicle height of the vehicle.
It is configured with R and these vehicle height sensors 2
A front vehicle height detection signal and a rear vehicle height detection signal are supplied from 2F, 22R to a control unit 25 as a vehicle height adjustment control unit.

Each of the sensors 22F and 22R in the vehicle height sensor 22 has one of the Hall IC element and the magnet mounted on the wheel FA side and the other mounted on the vehicle body B side, and based on the relative change between the wheel FA side and the vehicle body B side. The distance from the normal vehicle height level and the low vehicle height or the high vehicle height level is detected. The vehicle height sensor may be of various types, for example, one using a phototransistor.

Further, the speedometer 26 has a built-in vehicle speed sensor 27, which detects the vehicle speed and supplies a detection signal to the control unit 25. A switch type vehicle speed sensor is used, and in an electronic speedometer, a transistor open collector output type sensor is used.

Further, an acceleration sensor 28 is provided as a vehicle body attitude sensor for detecting the attitude change of the vehicle body. The acceleration sensor 28 is adapted to detect the attitude change of the pitch, roll and yaw on the spring of the vehicle. For example, when there is no acceleration, the weight is in a suspended state, and the light from the light emitting diode is blocked by the shielding plate and does not reach the photodiode, so that it is possible to detect that there is no acceleration. ing.

When the acceleration acts on the front, back, left, right, or up and down, the acceleration state of the vehicle body is detected by tilting or moving the weight.

Since the acceleration sensor 28 is provided on the spring, the harness connecting the acceleration sensor 28 and the control unit 25 does not cause bending displacement regardless of the stroke of the suspension. Further, the waterproof / dustproof treatment applied to the acceleration sensor 28 can be simplified.

Reference numeral 32 is a steering sensor that detects the rotation speed of the steering wheel 33, that is, the steering speed, 34 is an accelerator sensor that detects the steering speed of an accelerator pedal of an engine (not shown), and 35 is a reserve tank 20 via a three-way switching valve 36, respectively. The three-way switching valve 36 communicates with the reserve tank 20 by a signal from the control unit 25, and a pneumatic drive mechanism. One of the positions where the mechanism 35 communicates with the atmosphere can be selected, and this has the function of rotating the control rod 3 in the opposite direction to a predetermined position to shift from the soft state to the hard state. Instead of the pneumatic drive mechanism 35, a solenoid drive mechanism can be used. Reference numeral LF indicates a boundary between the engine room (left side of the broken line LF) and the vehicle compartment (between the broken lines LF and LR), and LR indicates a boundary between the vehicle compartment and the trunk room (right side of the broken line LR). There is. Further, reference numeral 30 denotes a hump stopper for preventing the cylinder of the shock absorber 1 from being relatively elevated on a bad road or the like, thereby damaging the wall surface or the like of the main air spring chamber 3. Reference numeral 31
Is a mode selection switch as a high vehicle height selection switch. By the way, the mode selection switch 31 automatically controls the vehicle height to the normal vehicle height or the low vehicle height, that is, to set the target vehicle height to the "medium" vehicle height or the "low" vehicle height. The vehicle height can be controlled to a high vehicle height, that is, a high mode in which a “high” vehicle height is set as a target vehicle height can be switched.

Next, the operation of the embodiment of the present invention configured as described above will be described. First, the overall operation will be described using the flow chart of FIG. First, in step S1, the vehicle height is automatically adjusted to "medium" as an initial setting.
Alternatively, the auto mode is set to set the vehicle height to "low". Then, the target vehicle height is set to normal, that is, "medium" vehicle height. Next, in step S2, it is determined whether or not the road surface on which the vehicle is traveling is a bad road, which will be described later with reference to FIG. 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 rough, the target vehicle height is also "high" vehicle. Set high. Then, in step S3, a target vehicle height determination which will be described in detail later with reference to FIG. And step S4
The vehicle height signal is read from the vehicle height sensor 22F (22R) into the control unit 25. Then, in step S5, it is determined whether or not the vehicle height detected by the vehicle height sensor 22F (22R) is equal to the target vehicle height set in step S3. If "NO" is determined in this step S5, the process proceeds to step S6 and the vehicle height adjustment toward the target vehicle height is started. For example, when the vehicle height detected in step S4 is lower than the target vehicle height, the vehicle height is increased by supplying air to the main air spring chamber 3 of each suspension unit. On the other hand, the above step S
When the vehicle height detected at 4 is higher than the target vehicle height, the air is exhausted from the main air spring chamber 3 of each suspension unit.
Then, returning to step S2, when the vehicle height becomes equal to the target vehicle height in step S5, the process proceeds to step S7 and the vehicle height adjustment of step S6 is completed.

Next, the rough road determination performed in step S2 of FIG. 3 will be described in detail with reference to the flow chart of FIG. First, in step S10, it is determined whether or not the vehicle speed is 40 km / h or more. If it is determined to be "YES", in step S11, the control unit 25 reads the time measured by a 2-second timer for measuring 2 seconds. And
In step S12, it is determined whether or not 2 seconds have been counted by the 2 second timer. If "NO" is determined in this step S12, the process proceeds to step S13, where the output signal of the vehicle height sensor 22F (22R) outputs the control unit 25.
The output signal of the acceleration (G) sensor 28 is read into the control unit 25 in step S14. After that, when 2 seconds are counted by the 2 second timer, "YES" is determined in step S12 and step S12 is executed.
Proceed to 16. In step S16, the 2-second timer is reset. Then, in step S17, the vehicle height sensor 22 detected in step S13 is detected.
It is determined from F (22R) whether the HH code, that is, the vehicle height higher than the high vehicle height level is output a predetermined number of times, for example, twice or more. If "YES" is determined in this step S17, the process proceeds to step S18. This step S18
Height sensor 2 detected in step S13 in
From 2F (22R), it is determined whether or not the LL code, that is, the vehicle height lower than the low vehicle height level is output twice or more. If "YES" is determined in this step S18, the process proceeds to step S19 and the rough road determination is established. This is done by setting the bad road flag. On the other hand, if "NO" is determined in the above step S17 or S18, the process proceeds to step S20 and the acceleration (G) sensor 28
It is determined whether or not the output signal is turned on a predetermined number of times, for example, twice or more. That is, it is determined whether or not the output of the acceleration (G) sensor 28 has passed through the low acceleration state and the high acceleration state twice or more within 2 seconds. If "YES" is determined in this step S20, the process proceeds to step S21, and the output signal of the acceleration (G) sensor 28 is 2 during the last 2 seconds.
It is determined whether or not it has been turned on more than once. This step S21
If it is determined to be "YES" in step S19, the process proceeds to step S19 and the rough road determination is established. If "NO" is determined in the above step S20, the process proceeds to step S22, and it is determined whether or not the bad road is determined every two seconds a desired number of times, for example, 6 times in succession. That is, it is determined whether or not there is no rough road determination for 12 seconds, and if "YES" is determined, the process proceeds to step S23 to cancel the rough road determination, that is, a good road determination. In this way, a bad road is determined by the output signal of the vehicle height sensor 22F (22R) or the acceleration (G) sensor 28. As described above, if the bad road is not determined in 12 seconds (2 seconds × 6 times) as the first case, the determination in step S22 is “YES” and the good road determination is made (step S23). The vehicle height can be lowered. Also, the second
In this case, when the vehicle overruns a projection or the like that is not judged to be a bad road in 12 seconds (2 seconds × 6 times), the vehicle height is lowered after 12 seconds as in the first case. Therefore,
Even if a bump or the like which is not judged as a bad road is overcome in 12 seconds, the good road judgment will not be unnecessarily delayed. This means that the output of the vehicle height sensor 22F (22R) does not exceed the set value (LL code or HH code) in the bad road determination means, and the output of the acceleration sensor 28 is ON twice or more for two consecutive flows. If not done, it is expensive because it is not judged as a bad road. In addition, the first 12 from the bad road section to the good road section
If the vehicle overshoots a projection that is judged to be a bad road within 2 seconds (2 seconds x 6 times), the vehicle height is lowered if a good road is established after the bad road is judged. Therefore, hunting can be prevented when the bad road section and the good road section are alternately repeated. By the way, the acceleration acting on the acceleration sensor 28 on a rough road basically does not change regardless of whether the vehicle height is standard or high, so that the rough road can be reliably detected. The process proceeds to step S23 where "NO" is determined in step S10. Next, the target vehicle height determination performed in step S3 of FIG. 3 will be described in detail with reference to FIG. First, in step S31, it is determined whether the rough road determination is established. If "YES" is determined in this step S31, step S
The program proceeds to 32 and the target vehicle height is set to high (HIGH). On the other hand, if "NO" is determined in the above step S31, the process proceeds to step S33, and it is determined whether or not the automatic (AUTO) mode is selected by the mode selection switch 31. If "YES" is determined in this step S33, the process proceeds to step S34 and it is determined whether or not the target vehicle height is set to normal (medium). If "NO" is determined in this step S34, it is determined in step S35 whether the vehicle speed detected by the vehicle speed sensor 27 is 70 km / h or less. If "NO" is determined in this step S35, the process proceeds to step S36 and the target vehicle height is set to "low" (low).

On the other hand, if "YES" is determined in the above step S34, the process proceeds to step S37, and it is determined whether or not the vehicle speed detected by the vehicle speed sensor 27 is 90 km / h or more. If "YES" is determined in this step S37, step S3
At 8, it is determined whether or not the vehicle speed is 90 km / h or more for 10 seconds. If "YES" is determined in this step S38, the process proceeds to the above step S36, and the target vehicle height is set low. That is, even if the target vehicle height is normal, when the vehicle speed is 90 km / h or more for 10 seconds, the target vehicle height is set to low (low) to ensure traveling stability. On the other hand, if "NO" is determined in the above step S37, the process proceeds to step S39 and the target vehicle height is set to normal (medium).

If it is determined to be "NO" in step S33, that is, the high vehicle height selection mode, the process proceeds to step S40 and it is determined whether the target vehicle height is set to a high level. "YES" in this step S40
If it is determined that the vehicle speed is 70 km /
It is determined whether or not h or more. If "NO" is determined in this step S41, the process proceeds to the above step S32. On the other hand, if "YES" is determined in the above step S41, it is determined in step S42 whether 10 seconds have elapsed since the vehicle speed became 70 km / h or more. If "NO" is determined in this step S42, the above step S32
If it is determined to be "YES" in step S42, the process proceeds to step S39.

On the other hand, if "NO" is determined in the above step S40, the process proceeds to step S43 and it is determined whether or not the target vehicle height is at the normal (medium) level. If "YES" is determined in this step S43, the process proceeds to the above step S44 and it is determined whether or not the vehicle speed is 50 km / h or less. This step S
If it is determined to be "YES" at 44, the above step S3 is performed.
Go to 2. On the other hand, in steps S43 and S44, "N
If it is determined to be "O", the process proceeds to step S34.

In this way, when the rough road determination is established, the target vehicle height is set high.

As described above in detail, according to the present invention, in a vehicle height control device capable of performing vehicle height control in three stages of "high", "medium", and "low", the acceleration acting on the vehicle body as a vehicle height sensor or sprung is detected. After the acceleration sensor determines that the vehicle is running on a bad road, the bad road determination is canceled when the road is a good road for more than the set time. It is possible to prevent an increase in the consumption of the battery power source due to the repetition of the vehicle height increase adjustment and the vehicle height decrease adjustment being alternately repeated.

Furthermore, according to the present invention, since the acceleration sensor detects the acceleration acting on the vehicle body which is on the spring, the acceleration sensor can be attached to the vehicle body side. Therefore, since the harness connecting the acceleration sensor and the controller does not relate to the stroke of the suspension and bending displacement does not occur, the waterproof / dustproof treatment can be greatly simplified.

In addition, since the acceleration acting on the vehicle body on a bad road does not basically change regardless of whether the vehicle height is the standard vehicle height or the high vehicle height, it is possible to reliably detect the bad road. Moreover, when the road changes from a good road to a bad road, the acceleration on the vehicle body on the spring often lags behind the vertical acceleration on the spring, but in the present invention, the vehicle height sensor also determines the bad road. Since it is configured to do so, there is no problem that the rough road determination is delayed.

In addition, the output of the vehicle height sensor does not exceed the set value in the rough road determination means, and the vehicle height in which the output of the acceleration sensor exceeds the set range within the predetermined time is not detected more than once, and the set value is set within the set time. If the acceleration is not detected more than a predetermined number of times more than a desired number of times in succession, the road is not judged to be a bad road.
6 times, 2 seconds is the set time, 6 times is a desired number of times) If you get over a projection that is not judged as a bad road, the vehicle height will be lowered after 12 seconds, and the projection will not be judged as a bad road in 12 seconds. It is possible to prevent the delay of the good road judgment from being unnecessarily delayed even if the vehicle gets over the road.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an automobile equipped with this device, FIG. 2 is an overall configuration diagram of this device, and FIGS. 3 to 5 are flow charts for explaining the operation of one embodiment. 11 ... Complexer 25 ... Control unit 27 ... Vehicle speed sensor 31 ... Mode selection switch

Front Page Continuation (72) Inventor Akio Furumura No. 1 Nakashinri, Hashime-cho, Okazaki-shi, Aichi Pref. Mitsubishi Motors Corporation, Passenger Car Technology Center (72) Inventor Masaru Sugawara 1 Nakashin-ri, Hashime-cho, Okazaki, Aichi Address Mitsubishi Motors Corporation, Passenger Car Technology Center (72) Inventor Shigeo Kaya, Nakasiri, No. 1, Hashime-cho, Okazaki City, Aichi Prefecture Mitsubishi Motors Corporation, Passenger Car Technology Center (72) Inventor Isao Hiroshima Machijiri Shinrikiri No. 1 Mitsubishi Motors Corporation, Passenger Vehicle Technology Center (56) References JP 59-63219 (JP, A) JP 59-75816 (JP, A) JP 59-34908 ( JP, A) JP-A-53-26021 (JP, A)

Claims (1)

[Claims] 1. A hydraulic suspension unit having a vehicle height adjusting fluid actuator, which is interposed between a vehicle wheel side member and a vehicle body side member, and a relative displacement between the wheel side member and the vehicle body side member. A vehicle height sensor for detecting a vehicle height based on the above, an acceleration sensor for detecting an acceleration acting on the vehicle body as a sprung body, and a vehicle height exceeding a set range within a set time is detected a predetermined number of times or more, Or a bad road determination means for determining a bad road when acceleration exceeding a set value is detected a predetermined number of times or more within a set time, and a vehicle height exceeding a set range is not detected more than once within the set time, In addition, a good road determination means for determining a good road when a state in which acceleration exceeding a set value is not detected more than a predetermined number of times within a set time is continuously detected a desired number of times, and a good road is determined. If target car If the normal vehicle height is set as, and a bad road is determined, the target vehicle height setting means for setting the vehicle height higher than the normal vehicle height as the target vehicle height, and the vehicle height by controlling the fluid actuator. And a control device for adjusting the vehicle height to the target vehicle height.