JP2529364Y2 - Electronic suspension system - Google Patents

Description

[Detailed description of the invention] Object of the invention [Industrial application field] The present invention relates to an electronically controlled suspension device for controlling the attitude of a vehicle.

2. Description of the Related Art When a vehicle is braked or stopped, a dive phenomenon occurs in which the vehicle height at the front of the vehicle body decreases. Therefore, conventionally, an electronically controlled suspension device that controls the vehicle's front-back direction inclination posture due to such a dive phenomenon in order to improve ride comfort and steering stability has been known. For example, there is known an apparatus in which a control valve is opened for a certain period of time to keep a vehicle body horizontal when acceleration during deceleration is equal to or higher than a predetermined value (Japanese Utility Model Application Laid-Open No. 60-119631).

[Problems to be Solved by the Invention] In such a conventional electronically controlled suspension device, the vehicle body can be kept horizontal when the acceleration exceeds a certain value. There has been a problem that the steering stability may not be sufficiently improved due to the fluctuation.

Accordingly, an object of the present invention is to provide an electronically controlled suspension device that further improves the steering stability during anti-dive control.

Configuration of the Invention [Means for Solving the Problems] In order to achieve the object, the present invention has the following configuration as means for solving the problems. That is, as illustrated in FIG. 1, in an electronically controlled suspension device having a vehicle height adjusting means M1 between a vehicle and wheels, an acceleration detecting means M2 for detecting longitudinal acceleration of the vehicle
Determining means M3 for determining whether or not to execute anti-dive control based on the acceleration detected by the acceleration detecting means M2; and, when performing the anti-dive control, reducing the ascending control amount on the descending side to descending on the ascending side. The control amount is smaller than the control amount, and the ascending control amount is smaller than the control amount for setting the vehicle posture to the reference vehicle height, and the descending control amount is larger than the control amount for setting the vehicle posture to the reference vehicle height. And an adjustment control means M4 for changing the controlled vehicle height with respect to a reference vehicle height by controlling the vehicle height adjustment means M1.

Further, the determining means M3 calculates a difference between a maximum value and a minimum value of acceleration detected within a predetermined time by the acceleration detecting means M2, and determines whether to execute anti-dive control based on the acceleration difference. The adjustment control means M4 performs control of the vehicle height adjustment means M1 with the ascending control amount and the descending control amount calculated according to the acceleration difference to thereby determine the vehicle height after control as a reference vehicle. It is good also as composition changed with respect to height.

[Operation] In the electronic control suspension device having the above-described configuration, the acceleration detection unit M2 detects the longitudinal acceleration of the vehicle, and the determination unit M3 executes the anti-dive control based on the acceleration detected by the acceleration detection unit M2. Determine whether or not.
And when the adjustment control means M4 executes the anti-dive control,
The ascending control amount on the descending side is smaller than the descending control amount on the ascending side, and the ascending control amount is smaller than the controlling amount for setting the vehicle posture to the reference vehicle height, and the descending control amount is based on the vehicle posture. Vehicle height adjustment means that is larger than the control amount for vehicle height
The vehicle height after control is changed with respect to the reference vehicle height by controlling M1. Therefore, it is possible to improve the contact property during the anti-dive control and improve the steering stability.

Further, when the determination means M3 makes a determination according to the acceleration difference, the determination means M3 calculates the difference between the maximum value and the minimum value of the acceleration detected within a predetermined time by the acceleration detection means M2, and Then, it is determined whether or not to execute the anti-dive control. Then, the adjustment control means M4 changes the controlled vehicle height with respect to the reference vehicle height by controlling the vehicle height adjustment means M1 with the ascending control amount and the descending control amount calculated according to the acceleration difference. . Therefore, the steering stability can be improved, and the tendency of the acceleration increase can be reliably grasped without responding to the instantaneous fluctuation of the acceleration, and the accurate attitude control according to the situation can be performed.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a schematic configuration diagram of an electronic control suspension device according to an embodiment of the present invention, and FIG. 3 is a pneumatic circuit diagram of the electronic control suspension device of the present embodiment. This electronically controlled suspension system includes a front wheel left suspension 1FL and a front wheel right suspension 1
FR, suspension 1RL on the rear left wheel, suspension 1RR on the right rear wheel, this suspension 1FL, 1FR, 1RL, 1
The RR is provided with gas springs 2FL, 2FR, 2RL, 2RR and shock absorbers 3FL, 3FR, 3RL, 3RR, respectively. As shown in FIG. 3, the gas springs 2FL, 2FR, 2RL, and 2RR include main gas chambers 4FL, 4FR, 4RL, and 4RR and sub gas chambers 5FL, 5FR, 5RL, and 5RR, respectively. , 4FR, 4RL, 4RR are part of diaphragm 6F
L, 6FR, 6RL, 6RR, so the main gas chamber 4F
The vehicle height can be changed by supplying and discharging air to L, 4FR, 4RL, and 4RR. In addition, the gas springs 2FL, 2FR, 2RL, 2RR drive the main gas chambers 4FL, 4FR, 4RL, 4RR and the sub gas chambers 5FL, 5FR, 5RL, 5RR by driving the spring motors 7FL, 7FR, 7RL, 7RR. The spring constant can be changed to each of “low”, “medium”, and “high” levels by switching communication / interruption or air flow rate.
The shock absorbers 3FL, 3FR, 3RL, and 3RR drive the absorber motors 8FL, 8FR, 8RL, and 8RR to change the flow rate through an orifice (not shown) to reduce the damping force.
It can be changed to each of "medium" and "high" stages.

On the other hand, in the air circuit AC, each gas spring 2FL, 2FR, 2RL, 2RR
A compressor 10 driven by a motor 9 is provided as a supply source of compressed air to be supplied to the compressor. The discharge side of the compressor 10 is connected to an air dryer 14 and an exhaust switching valve 16 via a check valve 12 for preventing backflow. Have been. Silica gel is sealed in the air dryer 14,
Removes moisture in compressed air. The air dryer 14 is provided with a supply switching valve 22 and a connection switching valve that can be connected / disconnected via a fixed throttle 18 and a check valve 20 for preventing backflow.
24 are connected to one of them. This supply switching valve 22
The other is connected to a relief valve 25 set at a predetermined pressure, and is connected to a high-pressure reserve tank 28 on the front wheel side via a high-pressure reserve switching valve 26 that can communicate and shut off, and can also communicate and shut off. It is connected to a high-pressure reserve tank 32 on the rear wheel side via a high-pressure reserve switching valve 30. These high pressure reserve tanks 28, 32
Pressure sensors 34 and 36 for detecting the air pressure in the high-pressure reserve tanks 28 and 32, and a relief valve 3 set to a predetermined pressure
8,40 respectively.

Further, the other of the supply switching valves 22 includes a main gas chamber 4FL via a leveling valve 42 which can be communicated and shut off, a main gas chamber 4FR via a leveling valve 44, and a main gas chamber 4RL via a leveling valve 46. And a main gas chamber 4RR via a leveling valve 48, respectively. Pressure sensors 50, 52, 54, 56 for detecting air pressure are connected to the main gas chambers 4FL, 4FR, 4RL, 4RR, respectively.

The main gas chamber 4FL on the left side of the front wheel is connected to the main gas chamber 4F on the right side of the front wheel via a discharge valve 58 that can be connected and disconnected.
R is connected to a low-pressure reserve tank 62 on the front wheel side via a similar discharge valve 60. Further, the main gas chamber 4RL on the left side of the rear wheel is connected to a low-pressure reserve tank 68 on the rear wheel side via a discharge valve 64 that can communicate and shut off, and the main gas chamber 4RR on the right side of the rear wheel is connected via a similar discharge valve 66. Each is connected. On the other hand, the low-pressure reserve tank 62 on the front wheel side and the low-pressure reserve tank 68 on the rear wheel side are connected to be always able to communicate. Pressure sensors 70 and 72 for detecting the air pressure of the low-pressure reserve tanks 62 and 68 are connected to these low-pressure reserve tanks 62 and 64, respectively.A relief valve 74 set to a predetermined pressure is connected to the low-pressure reserve tank 62 on the front wheel side. Is connected.

These low-pressure reserve tanks 62, 68 are connected to the other of the connection switching valves 24, and are connected to the suction side of the compressor 10 via a suction switching valve 76 that can communicate and shut off. A check valve 78 is connected to the suction side of the compressor 10 so that the air can be sucked. Without providing this check valve 78, the air circuit
It is also feasible if the AC is configured as a completely closed circuit and air or another gas, such as nitrogen gas, is introduced into the air circuit AC.

The exhaust switching valve 16, the supply switching valve 22, the connection switching valve 24, the high pressure reserve switching valves 26, 30, the leveling valves 42, 44, 46, 48, and the discharge valves 58, 6
In the present embodiment, the normally closed type is used for the suction switching valve 76.

In the present air circuit AC, the high-pressure reserve tanks 28, 32 and the low-pressure reserve tanks 62, 68 are provided on the front wheel side and the rear wheel side, respectively, but one high-pressure reserve tank and one common high-pressure reserve tank are provided on the front wheel side and the rear wheel side. Low-pressure reserve tank.

Further, as shown in FIG. 2, a clearance between the left front wheel and the vehicle body, a vehicle height sensor 80 for detecting the front left vehicle height, a vehicle height sensor 82 for detecting the right front vehicle height, and a left rear wheel. A vehicle height sensor 84 for detecting a vehicle height and a vehicle height sensor 86 for detecting a right rear vehicle height are provided. Each of the vehicle height sensors 80, 82, 84, and 86 outputs a signal corresponding to a positive vehicle height difference when the vehicle height is higher than a predetermined reference vehicle height, and outputs a signal corresponding to a negative vehicle height when the vehicle height is lower than the predetermined reference vehicle height. Outputs a signal corresponding to the height difference. On the other hand, a well-known steering angle sensor 90 for detecting a steering angle of a steered wheel 88, an acceleration sensor 92 as well-known acceleration detecting means for detecting lateral and longitudinal acceleration of the vehicle body, and an output shaft of a transmission (not shown). A vehicle speed sensor 93 for detecting the vehicle speed from the rotation speed. In addition, a vehicle height high switch 94 and a vehicle height low switch 96 for indicating a vehicle height by manual operation are also provided. Further, a brake switch 98 for detecting that the brake pedal 97 is depressed is also provided. The air circuit AC constitutes a vehicle height adjusting means.

Next, the electric system of this embodiment will be described with reference to the block diagram shown in FIG. Each suspension 1FL, 1FR, 1RL,
1RR is driven and controlled by the electronic control circuit 100 to control the attitude of the vehicle. As shown in FIG. 4, the electronic control circuit 100 includes a well-known CPU 102, a ROM 104, and a RAM 106 at the center of a logical operation circuit, and is an input / output circuit for performing input / output with the outside, here, a motor drive circuit 108, a valve drive Circuit 11
0, a sensor input circuit 112, a level input circuit 114, and the like are mutually connected via a common bus 116.

The CPU 102 includes pressure sensors 34, 36, 50, 52, 54, 56, 70, 72, vehicle height sensors 80, 82, 84, 86, a steering angle sensor 90, and an acceleration sensor 9.
2. Signals from the vehicle speed sensor 93 are input via the sensor input circuit 112, and signals from the vehicle height high switch 94, the vehicle height low switch 96 and the brake switch 98 are input via the level input circuit 114. On the other hand, based on these signals and the data in the ROM 104 and the RAM 106, the CPU 102 controls the compressor motor 9 and the spring motors 7FL, 7FR, 7R via the motor drive circuit 108.
L, 7RR and drive signals for driving the absorber motors 8FL, 8FR, 8RL, 8RR are output, and the exhaust switching valve 16, the supply switching valve 22, the connection switching valve 24,
Switching valves 26, 30 for high pressure reserve, leveling valve 42,
Drive signals are output to 44, 46, 48, discharge valves 58, 60, 64, 66 and suction switching valve 76, and each suspension 1FL,
1FR, 1RL, 1RR are controlled.

In the ROM 104, as shown in FIG. 10, a map MAP-a corresponding to a graph showing an acceleration difference ΔG described later on the vertical axis and an estimated longitudinal acceleration α described later on the horizontal axis, as shown in FIG. The vertical axis of the estimated longitudinal acceleration α, which will be described later, is plotted on the vertical axis, and the absolute value of the vehicle height correction amount C as a control amount is plotted on the horizontal axis. As the estimated longitudinal acceleration α increases, the absolute value of the vehicle height correction amount C also increases. The corresponding map MAP-b is stored.

The graph of FIG. 11, first, as shown in FIG. 12,
When anti-dive control is performed, the target vehicle height (two-dot chain line) is determined to be lower than the reference vehicle height (solid line) on both the front wheel side and the rear wheel side, and the front wheel side is lower than the rear wheel side. Next, a difference CF on the front wheel side and a difference CR on the rear wheel side with respect to the vehicle height (broken line) after the posture change of the vehicle without the anti-dive control is set as the control amount. To determine this control amount according to the longitudinal acceleration G, first,
The graph shown in FIG. 13 is obtained. The graph of FIG. 13 is a graph in which the longitudinal acceleration G generated in the vehicle is plotted on the vertical axis, and the variation ΔH from the reference vehicle height is plotted on the horizontal axis, and there is no anti-dive control according to the longitudinal acceleration G. FIG. 5 shows the amount of change on the front wheel side and the rear wheel side at the time, and the amount of change (target vehicle height) on the front wheel side and the rear wheel side after anti-dive control. From this graph, the control amount according to the longitudinal acceleration G, that is, the difference CF on the front wheel side and the difference CR on the rear wheel side between the target vehicle height and the change amount when there is no anti-dive control is obtained. The graph of FIG. 11 is determined from the CF and the difference CR on the rear wheel side.

Also, as shown in FIG. 14, the pressure P4F in the main gas chambers 4FL, 4FR on the front wheel side, which varies depending on the conditions of the empty vehicle, is stored in the ROM 104.
With the L and P4FR as parameters, the vertical axis represents the discharge change pressure ΔPFH that changes due to the outflow of air in the high-pressure reserve tank 28 on the front wheel side, and the horizontal axis represents the vehicle height correction amount C on the front wheel side on the horizontal axis. As shown in FIG. 15, the map MAP-c uses the pressures P4RL and P4RR in the main gas chambers 4RL and 4RR on the rear wheel side, which vary depending on the conditions of the empty vehicle, as parameters, and air in the low-pressure reserve tank 68 on the rear wheel side. A map MAP-d corresponding to a graph showing the suction change pressure ΔPRL that changes due to the inflow on the vertical axis and the vehicle height correction amount C on the rear wheel side on the horizontal axis, as shown in FIG. Reserve tank release change pressure Δ
When the compressed air is supplied to the front gas side main gas chambers 4FL and 4FR using PFH as a parameter, the vertical axis represents the pressure reduction time tCF required for the high pressure reserve tank pressure PFH to decrease in pressure according to the discharge change pressure ΔPFH. Front wheel high pressure reserve tank pressure P
FH / main gas chamber pressure P4FL, map MAP-e according to the graph showing the P4FR on the horizontal axis, and as shown in FIG. 17, the rear wheel side low pressure reserve tank suction change pressure ΔPFL is used as a parameter, Low pressure reserve tank 6 from main gas chamber 4RL, 4RR
When the air is released to the pressure change pressure ΔPRL, the vertical axis indicates the pressure increase time tDR required for the low-pressure reserve tank pressure PRL to change according to the suction change pressure ΔPRL, and the rear wheel side main gas chamber pressures P4RL, P4
A map MAP-f corresponding to a graph showing the RR / low-pressure reserve tank pressure PRL on the rear wheel side on the horizontal axis, the valve drive duty ratio described later on the vertical axis as shown in FIG. 18, and the correction amount ΔH on the horizontal axis. MAP-g corresponding to the graph shown in FIG.

Further, in the ROM 104, a map MAP-h showing the relationship between the discharge change pressure ΔPRH of the high pressure reserve tank 32 on the rear wheel side and the rear wheel side vehicle height correction amount C similar to FIG. A map MAP-i showing the relationship between the suction change pressure ΔPFL of the front wheel side low pressure reserve tank 62 and the front wheel side vehicle height correction amount C, and the pressure reduction time tCR of the rear wheel side high pressure reserve tank 32 similar to FIG.
Map MAP-j showing the relationship between the ratio of the main gas chamber pressures P4RL, P4RR to the rear wheel side high pressure reserve tank pressure PRH,
The boost time tD of the front-wheel low-pressure reserve tank 62 as in FIG. 17
A map MAP-k showing the relationship between F and the ratio of the front wheel side low pressure reserve tank pressure PFL to the main gas chamber pressures P4FL and P4FR is also stored.

Next, the processing performed in the electronic control circuit 100 will be described with reference to the flowcharts of FIGS.

When a key switch (not shown) is turned on, the electronic control suspension apparatus executes the suspension control routine shown in FIGS. 5 to 8 together with other control routines. First, initialization of data, flags, etc. (Step 20
0), pressure sensor 34, 36, 50, 52, 54, 56, 70, 72, vehicle height sensor
A process (step 205) of reading signals from the sensors 80, 82, 84, 86, the steering angle sensor 90, the acceleration sensor 92, and the vehicle speed sensor 93 via the sensor input circuit 112 is performed. Next, the vehicle state is calculated based on the signal from each sensor (step
200). For example, the current longitudinal acceleration G detected by the acceleration sensor 92 is read at regular intervals, for example, at intervals of 8 msec, and based on the sum of longitudinal accelerations G at regular intervals of ta, eg, at intervals of 32 msec, Equation (1) To calculate the average longitudinal acceleration n.

Also, the current lateral acceleration Gan detected by the acceleration sensor 92 is read at regular intervals, for example, at every 8 msec,
The average lateral acceleration ▼ n is calculated based on the sum of the lateral accelerations Gan every fixed time, for example, every 64 msec. Furthermore, the current vehicle height Hn detected by each of the vehicle height sensors 80, 82, 84, 86 is read at regular intervals, for example, at intervals of 8 msec, and based on the sum of vehicle heights Hn at regular intervals, for example, at intervals of 32 msec. To calculate the average vehicle height n.

Subsequently, if the later-described rapid control interruption flag is not set (step 215) and the later-described anti-dive flag is not set (step 220), the current vehicle speed V calculated in the process of step 210 becomes a predetermined value. Speed Va, for example, 25 km / h or more, and the current lateral acceleration Ga
Is smaller than a predetermined acceleration Ga0, for example, 0.3 g (g = gravity acceleration, the same applies hereinafter), the brake switch 97 is depressed to turn on the brake switch 98, and the steering wheel 88 detected by the steering angle sensor 90. If the absolute value of the steering angle θ is less than a predetermined angle θo, for example, 45 degrees, and the absolute value of the steering angular velocity is less than a predetermined angular velocity o, for example, 140 degrees / sec, the dive condition is such that anti-dive control is performed. A judgment is made (step 225). When it is determined that the dive condition is satisfied, first, as shown in FIG. 9, within a predetermined time tb immediately after determining that the dive condition is determined, for example, 96 ms, a predetermined time ta ( For example 3
The maximum average longitudinal acceleration GMAX (for example, 3) and the minimum average longitudinal acceleration GMIN of the three average longitudinal accelerations 1, 2, and 3 detected by the acceleration sensor 92 every 2 ms)
Acceleration difference ΔG (= GMAX−GM)
IN) is calculated (step 230).

Next, this acceleration difference ΔG is equal to a predetermined acceleration ΔGo, for example, 0.0
If the weight is 96 g or more (step 235), the anti-dive flag is set (step 240). Subsequently, according to the calculated acceleration difference ΔG, a predetermined map MA
P-a, that is, the estimated longitudinal acceleration α is temporarily obtained from the graph of FIG. 10 (step 245), and the estimated longitudinal acceleration α
Based on the predetermined map MAP-b, that is, the eleventh map
A front-wheel-side vehicle height correction amount CF and a rear-wheel-side vehicle height correction amount CR as control amounts are calculated from the graph in the figure (step 250).

Subsequently, based on the calculated vehicle height correction both CF and CR, the discharge change pressure ΔPFH of the high pressure reserve tank 28 for supplying and discharging air to and from each of the main gas chambers 4FL, 4FR, 4RL, and 4RR and the low pressure reserve tank A suction change pressure ΔPRL of 68 is calculated (step 255). This is shown in Figure 14 (Map MAP-c)
, The pressure in the front-wheel side gas spring as a parameter
Vehicle height correction amount C based on P4FL, P4FR and front wheel side vehicle height correction amount CF
The discharge change pressure ΔPFH of the front-wheel high-pressure reserve tank that changes by supplying air corresponding to F is calculated. Also, based on FIG. 15 (map MAP-d), the air corresponding to the vehicle height correction amount CR is obtained by using the rear wheel side main gas chamber pressures P4RL, P4RR and the rear wheel side vehicle height correction amount CR as parameters. Then, the suction change pressure ΔPRL of the rear wheel side low pressure reserve tank 68, which is changed by sucking the air, is calculated (step 255).

Next, based on the calculated discharge change pressure ΔPFH and suction change pressure ΔPRL, each valve drive time T for communicating the high pressure reserve tank 28 or the low pressure reserve tank 68 with each of the main gas chambers 4FL, 4FR, 4RL, 4RR is determined. Calculate (Step 26
0). This is shown in Fig. 16 (Map MAP-
e), the discharge change pressure ΔPFH as a parameter
And high pressure reserve tank pressure PFH / main gas chamber pressure P4FL, P
The pressure reduction time tCF of the front wheel side high pressure reserve tank 28 is calculated by 4FR. Next, the valve driving time TCF is calculated by the following equation (2) taking into account the pipe resistance coefficient, the valve coefficient and the like based on the step-down time tCF.

TCF = A × tCF + B (2) On the rear wheel side, based on the suction change pressure ΔPRL and the main gas chamber pressures P4RL, P4RR / low pressure reserve tank pressure PRL as parameters, based on FIG. 17 (map MAP-f). The boost time tDR of the wheel side low pressure reserve tank 68 is calculated. Next, the valve driving time TD is calculated by the following equation (3), taking into account the pipe resistance coefficient, the valve coefficient, and the like based on the boosting time tDR.
Calculate R.

TDR = C × tDR + D (3) After calculating each valve drive time TCF, TDR, a timer for a predetermined time t1, for example, about 60 msec, used for executing a process described later is set (step 265). Next, the high-pressure reserve switching valve 26, the leveling valves 42 and 44, the discharge valve 6
4, 66 are respectively driven (step 270). For example, the high-pressure reserve switching valve 26 and the leveling valves 42 and 44 according to the front wheel side valve drive time TCF, the discharge valves 64 and 66 according to the rear wheel side valve drive time TDR, and the respective valves 42, 44, Drive is performed so that the closing timing coincides with 64 and 66.

Therefore, as shown in FIG. 9, the vehicle height H on the front wheel side starts to change with a slight delay with the brake pedal 97 depressed and the longitudinal acceleration G changed as shown by the solid line. When the drive signal is output to the valve by executing the process of step 270, the valve starts driving after a delay time tta, for example, about 30 ms, and is compressed from the high-pressure reserve tank 28 to the main gas chambers 4FR and 4FL on the front wheel side. Air is rapidly supplied, and the air is rapidly discharged from the main gas chambers 4RL and 4RR on the rear wheel side to the low-pressure reserve tank 68. Therefore, a small delay time ttb
Later, for example, about 30 ms later, the effect on the vehicle height H due to the supply and exhaust of air appears. In FIG. 9, a change in the vehicle height H when air is not supplied or discharged is indicated by a two-dot chain line. Further, in the present embodiment, the predetermined time t1 set by executing the processing of step 265 is set equal to the sum of the delay times tta and ttb (t1 = tta + ttb). Thereby, the posture of the vehicle body is controlled lower than the reference vehicle height and the front wheel side is lower than the rear wheel side, as in the target vehicle height shown in FIG. 12, so that aiming is prevented.

When the process of step 270 is executed, the control routine is repeatedly executed after executing the process described later, and it is determined that the anti-dive flag is set by executing the process of step 220 described above. If it is determined that the control flag is not set (step 27
5) It is determined whether or not a predetermined time t1 of the timer set by execution of the processing of step 265 has elapsed (step
280). After the predetermined time t1 has elapsed, each shock absorber 3F
When the damping forces of L, 3FR, 3RL, and 3RR are not switched (step 285), the damping force is switched and the damping force is increased by one level to prevent the vehicle from shaking due to sudden gas supply and exhaust (step 290). ). For example, when the damping force is “low”, the absorber motors 8FL, 8FR, 8RL, and 8RR are driven to switch the damping force to “medium”. When the damping force is “medium”, the damping force is switched to “high”. If the damping force is switched (step 290), or it is determined that the predetermined time t1 has not elapsed (step 280), or if it is determined that the damping force has been switched (step 285),
Each valve drive time TCF, T by executing the process of step 270
Until driving of each valve according to DR is completed (Step 29
5) Repeat this control routine. When driving of each valve is completed (step 295), the maximum acceleration p of the average longitudinal acceleration is detected (step 300). If it is determined that the maximum acceleration p has been detected (step 30)
5), the damping force of the shock absorbers 3FL, 3FR, 3RL, 3RR whose damping force has been raised by one level by executing the processing of step 290 is restored (step 310).

Next, when the depression of the brake pedal 97 is relaxed, the longitudinal acceleration G decreases, and the current average longitudinal acceleration becomes a predetermined ratio y of the maximum acceleration p, for example, 70% or less (step 315), the control returns. A control flag is set (step 320). Subsequently, a timer for a predetermined time t2, for example, about 60 msec, which is used for executing the processing described later, is set (step 325). When you set the timer,
Each valve is driven in order to return the vehicle, which is lower than the reference vehicle height and is controlled to the forward leaning posture by performing the above-described process, to the reference vehicle height (step 330). That is, in accordance with the front wheel side vehicle height correction amount CF and the rear wheel side vehicle height correction amount CR calculated by executing the processing of step 250 described above, step 255,
The posture is controlled in the direction opposite to the posture control direction by executing the processes of 260 and 270. First, map MAP-
The front-wheel-side low-pressure reserve tank changes by inhaling air corresponding to the vehicle height correction amount CF based on the front-wheel-side gas spring internal pressures P4FL, P4FR and the front wheel-side vehicle height correction amount CF based on i. The suction change pressure ΔPFL of 62 is calculated. Further, based on the vehicle height correction amount CF on the rear wheel side, the discharge change pressure ΔPRH of the rear wheel side high pressure reserve tank 32 is also mapped M.
It is calculated based on AP-h. Next, based on the calculated suction change pressure ΔPFL and discharge change pressure ΔPRH, the valve drive for the front wheels is performed in consideration of the map MAP-j, k and the pipeline resistance in the same manner as in the processing of step 260 described above. The time TDF and the rear wheel side valve drive time TCR are calculated. In accordance with the calculated front wheel side valve drive time TDF, the discharge valves 58 and 60 are driven in accordance with the rear wheel side valve drive time TCR.
Switching valve for high pressure reserve 30, leveling valve 46, 48
Are driven such that the closing timings of the valves 30, 46, 48, 58, and 60 match (step 330).

Next, each valve is driven to repeatedly execute the present control routine. When the anti-dive flag and the return control flag are set (steps 220 and 275), and the vehicle height feedback flag described later is not set ( Step 335), it is determined whether or not a predetermined time t2 of the timer set by execution of the processing of step 325 has elapsed (step 340). When the predetermined time t2 has elapsed and the damping force of each of the shock absorbers 3FL, 3FR, 3RL, 3RR has not been switched (step 345), the damping force is switched,
The damping force is increased by one level (step 350). For example, when the damping force is “low”, the absorber motor 8FL,
Drive 8FR, 8RL, 8RR to switch the damping force to “medium”.
When the damping force is “medium”, the damping force is switched to “high”. The damping force is switched (step 350), or it is determined that the predetermined time t2 has not elapsed (step 34).
0) or when it is determined that the damping force has already been switched (step 345), this process is performed until the drive of each valve according to each valve drive time TDF, TCR by execution of the process of step 330 ends (step 355). Repeat the control routine. After each valve is driven (step
355), the absolute value of the average longitudinal acceleration is the predetermined acceleration G1,
For example, if the weight is 0.15 g or less (step 360), a timer for a predetermined time t3, for example, about 300 msec used for execution of the processing described later is set (step 365). Subsequently, when the absolute value of the average vehicle height is equal to or greater than the predetermined value ΔH0, a vehicle height feedback flag is set (step 375) to perform feedback control to the reference vehicle height (step 370), and the valve drive duty ratio D is set. It is calculated (step 380).
Wheels with a negative average vehicle height are installed in the main gas chambers 4FL, 4FR, 4RL, 4RR corresponding to the wheels in the high-pressure reserve switching valves 26,3.
0, in order to drive the leveling valves 42, 44, 46, 48 to supply compressed air from the high pressure reserve tanks 28, 32, the valve drive duty ratio according to the average vehicle height (= correction amount ΔH) according to FIG. D is calculated. The wheels having a positive average vehicle height H are the main gas chambers 4FL, 4FR, 4R corresponding to the wheels.
In order to drive the discharge valves 58, 60, 64, 66 from L, 4RR to discharge air to the low-pressure reserve tanks 62, 68, the first
Referring to FIG. 8, a valve drive duty ratio D corresponding to the average vehicle height (= correction amount ΔH) is calculated (step 380).
After calculating the valve drive duty ratio D, each valve is driven according to the duty ratio D (step 385).

On the other hand, each valve is driven, the control routine is repeatedly executed, and when it is determined that the vehicle height feedback flag is set by executing the processing of step 335 (step 335), the setting is executed by executing the processing of step 365. It is determined whether or not a predetermined time t3 of the timer has elapsed (step 390). When the predetermined time t3 has elapsed and the damping force of each of the shock absorbers 3FL, 3FR, 3RL, 3RR has not been switched (step 395), the shock absorber 3F whose damping force has been increased by one level by executing the processing of step 350.
The damping forces of L, 3FR, 3RL, and 3RR are restored (step 400). By returning the damping force to the original value and executing the processing of step 370, it is determined that the absolute value of the average vehicle height H is smaller than the predetermined value ΔH0, and that the damping force has already been switched (step
405), clear all the flags mentioned above (step 4)
Ten).

On the other hand, if it is determined in step 215 that a rapid control flag described later has been set, target vehicle height control (step 411) is performed. In this target vehicle height control,
The absolute value of the difference between the vehicle height H of each wheel detected by each vehicle height sensor 80, 82, 84, 86 and the target vehicle height Hn during normal straight running is a predetermined value ΔH, for example, the minimum value that can control the vehicle height If it is larger, the compressor 10 and each valve are driven to set the vehicle height H of each wheel to the target vehicle height Hn. For example, a wheel lower than the target vehicle height Hn drives the compressor 10 and also drives the supply switching valve 22 and one of the leveling valves 42, 44, 46, and 48 corresponding to the wheel having the low vehicle height H, and the vehicle height is reduced. Compressed air is supplied to one of the main gas chambers 4FL, 4FR, 4RL, and 4RR according to the low H wheel. The amount of compressed air supplied at this time is an amount according to the capacity of the compressor 10, the flow path resistance, and the like, and the vehicle height H gradually reaches the target vehicle height Hn. When the target vehicle height Hn is reached, the driving of the compressor 10 and the valves 22, 42, 44, 46, 48 is stopped.

The wheels higher than the target vehicle height Hn are, for example, the exhaust switching valve 16, the connection switching valve 24, and any of the discharge valves 58, 60, 64 corresponding to the wheels having a higher vehicle height H without driving the compressor 10. , 66 to discharge the air in one of the main gas chambers 4FL, 4FR, 4RL, 4RR corresponding to the wheel having a high vehicle height H to the atmosphere. The discharge amount at this time is an amount corresponding to the throttle 18 and the flow path resistance, and the vehicle height H is gradually reduced to the target vehicle height.
Reach Hn. When the target vehicle height Hn is reached, each valve 16, 24, 58, 60,
Stop driving of 64 and 66.

When it is determined that the dive condition is not satisfied by executing the processing of step 225, or when it is determined that the acceleration difference ΔG is smaller than the predetermined acceleration ΔGo by executing the processing of step 235, it is determined that another rapid control condition is satisfied (step 412). ),
Another rapid control is performed (step 413). As another quick control, taking anti-squat control as an example, similarly to anti-dive control, for example, the time required to pass through three of the six throttle opening degrees detected by a throttle opening sensor (not shown) is predetermined. Time, for example, within 80 msec, and the variation of each vehicle height detected by the vehicle height sensors 80, 82, 84, 86 is less than a predetermined value, for example, less than 24 mm, and the absolute value of the lateral acceleration Ga is the predetermined acceleration Gao, For example, a steering wheel smaller than 0.3 g and detected by the steering angle sensor 90
The absolute value of the steering angle θ of 88 is smaller than a predetermined angle θo, for example, 45 degrees, and the absolute value of the steering angular velocity is a predetermined angular velocity o, for example,
If it is smaller than 140 degrees / sec, it is determined that the squirt condition is such that anti-squirt control is performed. When the acceleration difference ΔG, which is the difference between the maximum average longitudinal acceleration GMAX and the minimum average longitudinal acceleration GMIN detected within a predetermined time immediately after determining the squat condition, is equal to or greater than a predetermined acceleration, for example, 0.072 g, A vehicle height correction amount C as a predetermined control amount is obtained according to the acceleration difference ΔG, and the rear wheel side vehicle height is higher than the front wheel side vehicle height according to the vehicle height correction amount C. To control.

Next, the above control is performed, and the high-pressure reserve tanks 28, 3
The compressed air in 2 is consumed, and the pressure PFH in the high-pressure reserve tank 28 detected by the pressure sensor 34 or the pressure PRH in the high-pressure reserve tank 32 detected by the pressure sensor 36 performs the rapid attitude control. When the pressure falls below a predetermined high-pressure interruption pressure Pa, for example, 9.5 atm (absolute pressure) (step 415), a rapid control interruption flag is set (step 420). Subsequently, the compressor 10 is driven by the compressor motor 9, and at the same time, the supply switching valve 22, one of the leveling valves 42, 44, 46, 48, the suction switching valve 76, and the like are driven (step 425), and the low-pressure reserve tank is operated. When the air in the tanks 62, 68 or the pressure in the low-pressure reserve tanks 62, 68 is lower than the atmospheric pressure, the atmosphere is compressed through the check valve 78 and any one of the main gas chambers 4F
Supply to L, 4FR, 4RL, 4RR.

On the other hand, in step 415, when the pressure is equal to or higher than the high-pressure interruption pressure Pa and the rapid control interruption flag is not set (step 430), the pressure PFL in the low-pressure reserve tank 62 detected by the pressure sensor 70 or the pressure sensor 72 is detected.
PRL in the low-pressure reserve tank 68 detected by
However, when the pressure exceeds a predetermined low-pressure interruption pressure Pb at which the rapid attitude control cannot be performed, for example, 6 atm (absolute pressure) (step 435), the processing of steps 420 and 425 is executed.

On the other hand, if the rapid control interruption flag is set (step 430), that is, if the compressor 10 or the like is driven, the pressure PFH in the high-pressure reserve tank 28 and the pressure PRH in the high-pressure reserve tank 32 become rapid attitude control. The compressor 10 and the like are driven until a predetermined pressure Pc (for example, 11 atm (absolute pressure)) greater than the high-pressure interrupting pressure Pa, which is necessary to execute the operation with a margin (Step 440).
5) When the pressure exceeds the predetermined pressure Pc (step 440), the processing of step 435 is executed.

In step 435, it is determined that the pressure is lower than the low pressure interruption pressure Pb, and the rapid control interruption flag is set (step 445), and the pressure PFL in the low pressure reserve tank 62 and the pressure PRL in the low pressure reserve tank 68 are rapidly controlled. If the pressure exceeds a predetermined pressure Pd, for example, 5 atm (absolute pressure), which is smaller than the low pressure interruption pressure Pb necessary to execute the process with a margin (step 450), the processing of steps 420 and 425 is executed. When the pressure falls below the predetermined pressure Pd (Step 450), the processing of Steps 420, 425, etc. is executed, and the high pressure reserve tank 2
Clearing the rapid control interruption flag assuming that both pressures in the low pressure reserve tanks 62 and 68 are less than the predetermined pressure Pd because both pressures in the pressure tanks 8 and 32 are equal to or higher than the predetermined pressure Pc. (Step 455), the compressor 10 is driven by the compressor motor 9, the supply switching valve 22,
Driving of the leveling valves 42, 44, 46, 48, the suction switching valve 76, and the like is stopped (step 460). If it is determined in step 445 that the rapid control interruption flag has not been set, the processing in steps 455 and 460 is executed. When the process of step 425 or 460 is executed, the process temporarily goes to “NEXT”.

Note that the processing of step 235 operates as the determination means M3, and the processing of steps 235, 245 to 260, 270 functions as the adjustment control means.

As described above, the electronically controlled suspension device of the present embodiment provides an acceleration difference between the maximum average longitudinal acceleration GMAX and the minimum average longitudinal acceleration GMIN within a predetermined time tb immediately after determining that the dive condition is satisfied (step 225). ΔG is calculated (step 230). This acceleration difference ΔG is equal to the predetermined acceleration ΔGo
When the above is the case, it is determined that the anti-dive control is to be executed, and a vehicle height correction amount C as a predetermined control amount is obtained in accordance with the acceleration difference ΔG, and the gas spring 4FL is determined in accordance with the vehicle height correction amount C. , 4FR, 4RL, 4RR and reserve tanks 28, 32, 6
It communicates with and shuts off the gas springs 4FL, 4FR, 4RL, and 4RR to control the attitude of the vehicle (steps 235 and 245).
Or 260,270).

Therefore, according to the electronic control suspension device of the present embodiment, the control amount for lowering the vehicle body on the lower side is made smaller than the lower control amount on the upper side, and the control amount for raising the vehicle attitude is set to the reference vehicle height. The lowering control amount is controlled to be larger than the control amount for setting the vehicle attitude to the reference vehicle height.

Therefore, the position of the center of gravity of the vehicle body can be lowered as compared to before the control, the change of the grounding load due to the longitudinal acceleration is reduced, the control performance and the like are improved, the steering stability is improved, and the vertical movement of the vehicle body is improved. And steering stability is also improved from this point.

Further, by calculating the acceleration difference ΔG, the tendency of the increase in the acceleration can be reliably grasped without responding to the instantaneous fluctuation of the acceleration, and the attitude control can be accurately performed with good response according to the situation. Therefore, it is possible to improve ride comfort and steering stability.

Next, an air circuit AC2 of another embodiment different from the air circuit AC of FIG. 3 will be described with reference to FIG. In this air circuit AC2, the same components as those of the air circuit AC described above are denoted by the same reference numerals, and description thereof is omitted.

In the air circuit AC2, the high-pressure reserve tank 28a and the low-pressure reserve tank 62a on the front wheel side, and the high-pressure reserve tank 32a and the low-pressure reserve tank 68a on the rear wheel side are integrally formed. One of the high-pressure reserve switching valve 26 connected to the high-pressure reserve tank 28a on the front wheel side and the high-pressure reserve switching valve 30 connected to the high-pressure reserve tank 32a on the rear wheel side are connected to each other by a communication switching valve 501 capable of communicating and shutting off. Connected through. Therefore, even if the two high-pressure reserve switching valves 26 and 30 are simultaneously driven, the high-pressure reserve tanks 28a and 32a do not communicate with each other unless the communication switching valve 501 is driven.

The low-pressure reserve tank 62a on the front wheel side is connected to one of a low-pressure reserve switching valve 502 that can communicate and shut off, and the other of the low-pressure reserve switching valve 502 is a suction switching valve 76 and both front-wheel discharge valves 58, 60. Communication switching valve 504 which is connected to
Connected to one of the The other of the communication switching valve 504 is a low-pressure reserve switching valve 506 that can be connected and disconnected.
Connected to the low-pressure reserve tank 68a via
It is connected to both discharge valves 64, 66 on the rear wheel side. Further, a relief valve 508 set to a predetermined pressure is connected to the low-pressure reserve tank 68a. Therefore, the low-pressure reserve tanks 62a, 68a are connected to the low-pressure reserve switching valves 502, 5,
Even when the low pressure reserve switching valves 502 and 506 are driven by the shutoff from other valves and the like by the 06, the low pressure reserve tanks 62a and 68a do not communicate with each other unless the communication switching valve 504 is driven.

The air circuit AC2 connects the main gas chambers 4FL, 4FR to the low-pressure reserve tank 62a by driving the front-wheel low-pressure reserve switching valve 502 and the discharge valves 58, 60. Also, a switching valve 50 for low pressure reserve on the rear wheel side
By driving the discharge valves 6 and the discharge valves 64 and 66, the main gas chambers 4RL and 4RR can communicate with the low-pressure reserve tank 68a.

Thus, the air circuit AC2 is connected to both high-pressure reserve tanks 2
8a, 32a and high-pressure reserve switching valves 26, 30 and low-pressure reserve switching valve 50 for each low-pressure reserve tank 62a, 68a.
2,506, communication switching valves 501,504, reserve tank
The pressure can be controlled for each of 28a, 32a, 62a, and 68a.

Although the embodiment of the present invention has been described above, the present invention is not limited to such an embodiment, and it goes without saying that the present invention can be implemented in various modes without departing from the gist of the present invention.

Effects of the Invention As described in detail above, according to the electronic control suspension device of the present embodiment, the descending control amount on the descending side of the vehicle body is smaller than the descending control amount on the ascending side, and the ascending control amount is the vehicle attitude. Is smaller than the control amount for setting the vehicle height to the reference vehicle height, and the descending control amount is controlled to be larger than the control amount for setting the vehicle posture to the reference vehicle height. Therefore, the reference vehicle height is good for both the front wheel side and the rear wheel side. Lower, and the front wheel side is lower than the rear wheel side,
The position of the center of gravity of the body can be lowered compared to before control,
The spring constant increases, the contact property increases, the change in the contact load due to longitudinal acceleration decreases, the braking performance etc. improve, steering stability can be improved, and the vertical movement of the vehicle body is small, and Stability is improved. In the case where the determination means makes a determination according to the acceleration difference, by calculating the acceleration difference and performing control in accordance with the acceleration difference, the steering stability is improved, and without responding to the instantaneous fluctuation of the acceleration. Thus, it is possible to accurately grasp the increasing tendency of the acceleration and perform the attitude control accurately and responsively according to the situation.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a basic configuration of the present invention, FIG. 2 is a schematic configuration diagram of an electronic control suspension device as one embodiment of the present invention, FIG. 3 is a pneumatic circuit diagram of the present embodiment,
FIG. 4 is a block diagram showing a configuration of an electric system of the present embodiment,
5 to 8 are flowcharts showing an example of a control routine performed in the control circuit of the present embodiment.
The graph shows the relationship between the longitudinal acceleration, the control signal, the vehicle height and time, FIG. 10 shows the relationship between the acceleration difference and the estimated longitudinal acceleration, and FIG. 11 shows the estimated longitudinal acceleration and the vehicle height correction. FIG. 12 is a graph showing the relationship with respect to the reference vehicle height, FIG. 13 is a graph showing the relationship between the longitudinal acceleration and the amount of change from the reference vehicle height, and FIG. 14 is the discharge change pressure. 15 is a graph showing the relationship between the suction change pressure and the vehicle height correction amount, and FIG. 16 is a relationship between the pressure reduction time and the high pressure reserve tank pressure / main gas chamber pressure. FIG. 17 is a graph showing the relationship between the pressure rise time and the main gas chamber pressure / low pressure reserve tank pressure, and FIG.
FIG. 18 is a graph showing the relationship between the drive duty ratio and the correction amount, and FIG. 19 is an air circuit diagram as another embodiment. 2FL, 2FR, 2RL, 2RR… Gas spring 28,28a, 32,32a… High pressure reserve tank 34,36,50,52,54,56,70,72… Pressure sensor 62,62a, 68,68a… Low pressure reserve tank 100 ... Electronic control circuit

Continuing on the front page (72) Inventor Osamu Takeda 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Toshio Aburaya 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (56) Reference Document JP-A-59-190016 (JP, A) JP-A-62-198510 (JP, A) JP-A-61-150809 (JP, A)

Claims (2)

(57) [Scope of request for utility model registration] 1. An electronically controlled suspension device having a vehicle height adjusting means between a vehicle and wheels, comprising: an acceleration detecting means for detecting a longitudinal acceleration of the vehicle; Determining means for determining whether or not to execute the dive control; and during the execution of the anti-dive control, the ascending control amount on the descending side is smaller than the descending control amount on the ascending side, and the ascending control amount determines the vehicle attitude. The vehicle height after control is controlled by controlling the vehicle height adjusting means by an amount smaller than the control amount for setting the reference vehicle height and the descending control amount is larger than the control amount for setting the vehicle posture to the reference vehicle height. An electronically controlled suspension device, comprising: an adjustment control unit that changes the vehicle speed with respect to a reference vehicle height. 2. The method according to claim 1, wherein the determining means calculates a difference between a maximum value and a minimum value of the acceleration detected within a predetermined time by the acceleration detecting means, and determines whether to execute anti-dive control based on the acceleration difference. The adjustment control means controls the vehicle height adjustment means with the ascending control amount and the descending control amount calculated according to the acceleration difference, and thereby adjusts the vehicle height after control to a reference vehicle height. The electronic control suspension device according to claim 1, wherein the electronic control suspension device is registered in a utility model registration.