JP6900841B2 - Air spring controller - Google Patents

Description

Embodiments of the present invention relate to an air spring control device.

Conventionally, a vehicle equipped with an air spring control device using an air spring using compressed air has been known. In such an air spring control device, the spring constant is changed and the characteristics (hardness) of the air spring are adjusted by opening and closing the spring constant switching valve provided between the air spring and the air tank.

Japanese Patent No. 4715380

However, if the spring constant switching valve closes when the air spring is greatly extended or contracted, the pressure on the air spring side fluctuates when the air spring returns to the neutral state, but the spring constant switching valve The pressure is maintained on the air tank side because the valve is closed. In such a case, the pressure difference (differential pressure) between the inside of the air tank and the inside of the air spring becomes large.

Therefore, in the conventional air spring control device, for example, when the pressure of the air tank is higher than the pressure of the air spring to some extent or more, the pressure on the air tank side presses the spring constant switching valve to prevent it from moving smoothly, and the valve opens. It could be difficult to do. Further, when the pressure of the air spring is larger than the pressure of the air tank to some extent or more, the pressure on the air spring side exerts pressure on the spring constant switching valve to prevent it from moving smoothly, which may make it difficult to open the valve.

Therefore, one of the problems of the embodiment is to provide an air spring control device capable of suppressing the state in which the spring constant switching valve does not move smoothly.

As an example, the air spring control device according to the embodiment of the present invention is provided corresponding to the wheels of the vehicle body and operates according to the flow state of the working fluid, and the air spring is provided corresponding to the air spring and the working fluid. An on-off valve that can change the spring constant of the air spring by interposing between the air spring and the tank and allowing or blocking the flow of the working fluid, and the stroke of the air spring. It is provided with a control unit that limits the valve closing operation of the on-off valve according to the amount or the pressure in the air spring or the tank. Therefore, according to the air spring control device according to the embodiment, as an example, it is possible to prevent the spring constant switching valve (on-off valve) from not moving smoothly.

As an example, the air spring control device further includes a vehicle height detection unit that detects the vehicle height of the vehicle body. Further, the control unit calculates the stroke amount of the air spring from the detected vehicle height, and when the stroke amount is equal to or more than the first threshold value or equal to or less than the second threshold value smaller than the first threshold value, the on-off valve is used. Limit the valve closing operation of. Therefore, according to the air spring control device according to the embodiment, as an example, it is possible to prevent the differential pressure between the inside of the tank and the inside of the air spring from becoming higher than the permissible range in advance.

In the above-mentioned air spring control device, as an example, a first absolute value of the stroke amount that the air spring reaches the first threshold value and a second stroke amount that the air spring reaches the second threshold value from the neutral state. It is different from the absolute value. Therefore, according to the air spring control device according to the embodiment, as an example, it is possible to control the opening / closing operation of the spring constant switching valve (opening / closing valve) according to the characteristics of the air spring.

As an example, the air spring control device further includes a pressure detection unit that detects the pressure in the air spring or the tank. Further, the control unit limits the valve closing operation of the on-off valve when the detected pressure is out of the predetermined range in the state where the on-off valve is opened. Therefore, according to the air spring control device according to the embodiment, as an example, it is possible to prevent the spring constant switching valve (on-off valve) from not moving smoothly with higher accuracy.

As an example, the air spring control device further includes a vehicle height adjusting valve that adjusts the vehicle height of the vehicle body by changing the inflow amount of the working fluid to the air spring. Further, the control unit changes the first threshold value and the second threshold value according to the vehicle height adjusted by the vehicle height adjusting valve. Therefore, according to the air spring control device according to the embodiment, as an example, the spring constant switching valve (on-off valve) is opened and closed with higher accuracy in response to the change in the internal pressure at the neutral position of the air spring due to the vehicle height adjustment. You can control it.

FIG. 1 is a diagram showing an example of the configuration of the air spring control device according to the first embodiment. FIG. 2 is a block diagram showing an example of the functional configuration of the ECU according to the first embodiment. FIG. 3 is a graph illustrating an example of the relationship between the stroke amount of the air spring and the internal pressure of the air spring. FIG. 4 is a flowchart showing an example of the procedure of the air spring control process according to the first embodiment. FIG. 5 is a flowchart showing an example of the procedure of the valve closing restriction process according to the first embodiment. FIG. 6 is a diagram showing an example of the configuration of the air spring control device according to the second embodiment. FIG. 7 is a block diagram showing an example of the functional configuration of the ECU according to the second embodiment. FIG. 8 is a flowchart showing an example of the procedure of the valve closing restriction process according to the second embodiment.

(Embodiment 1)
FIG. 1 is a diagram showing an example of the configuration of the air spring control device 10 according to the present embodiment. As shown in FIG. 1, the air spring control device 10 includes air springs 12FR, 12FL, 12RR, 12RL, air tanks 26FR, 26FL, 26RR, 26RL, spring constant switching valves 24FR, 24FL, 24RR, 24RL, and a vehicle. High sensors 58FR, 58FL, 58RR, 58RL, main flow path 20, pipes 16FR, 16FL, 16RR, 16RL, vehicle height adjustment valves 14FR, 14FL, 14RR, 14RL, compressor unit 30, ECU (Electronic Control Unit) 56 and.

The air springs 12FR, 12FL, 12RR, and 12RL each function as a vehicle height adjusting unit. The air springs 12FR, 12FL, 12RR, and 12RL are provided corresponding to the wheels of the vehicle (not shown). Hereinafter, when each air spring is not distinguished, it is simply referred to as "air spring 12". The air spring 12 is connected to each wheel.

Each air spring 12 changes the suspended state of the wheels with respect to the vehicle body according to the supply and discharge of the working fluid (for example, air). Further, the air spring 12 has a function of absorbing the vibration of the vehicle by the elasticity of the internal air. The air springs 12FR and 12FL may be referred to as front wheel height adjusting portions. Further, the air springs 12RR and 12RL may be referred to as a rear wheel vehicle height adjusting unit. A known structure can be used for the air spring 12.

The air tanks 26FR, 26FL, 26RR, and 26RL are tanks that are provided corresponding to each of the air springs 12 and can hold air. Hereinafter, when each air tank is not distinguished, it is simply referred to as "air tank 26". The air tank 26 is made of, for example, metal or resin.

Further, the pipes 16FR, 16FL, 16RR, 16RL connect between each air spring 12 and the air tank 26. Hereinafter, when each pipe is not distinguished, it is simply referred to as "pipe 16". Air can flow (inflow and outflow) between each air spring 12 and each air tank 26 through each pipe 16.

The spring constant switching valves 24FR, 24FL, 24RR, and 24RL are on-off valves that are provided between the air springs 12 and the air tanks 26 to switch the spring constants of the air springs 12. Hereinafter, when each spring constant switching valve is not distinguished, it is simply referred to as "spring constant switching valve 24".

As shown in FIG. 1, each spring constant switching valve 24 is provided in the middle of each pipe 16. Each spring constant switching valve 24 has, for example, a solenoid and a spring that are ON / OFF controlled. Each spring constant switching valve 24 is normally opened by the electromagnetic force generated by the solenoid when the specified control current is supplied, and is opened by the urging force of the spring when the solenoid is in the non-energized state. It is a type electromagnetic control valve.

That is, when the solenoid is in the non-energized state, the spring constant switching valve 24 is in the open state, so that the air spring 12 and the air tank 26 are in a communicating state in which air can flow in both directions. Further, when the solenoid is energized and the spring constant switching valve 24 is closed, the flow of air between the air spring 12 and the air tank 26 is cut off.

When the spring constant switching valve 24 is closed, the flow of air to the air tank 26 is cut off, so that the spring constant of the air spring 12 becomes high. In this case, the characteristics of the air spring 12 become hard. Each spring constant switching valve 24 is individually opened / closed controlled by the ECU 56 described later. For example, a drive IC (not shown) controls ON / OFF of supply of a specified control current to the spring constant switching valve 24 based on a control signal from the ECU 56. The drive IC (not shown) may be provided outside the ECU 56 or may be included inside the ECU 56.

The vehicle height sensors 58FR, 58FL, 58RR, and 58RL are connected to suspension arms (lower arms, etc.) that connect the vehicle body and wheels (not shown) for each wheel, and detect the amount of vertical displacement between the suspension arm and the vehicle body. .. Hereinafter, when each vehicle height sensor is not distinguished, it is simply referred to as "vehicle height sensor 58". Further, the vehicle height sensor 58 may adopt a configuration in which the vehicle height is measured by directly measuring the distance to the road surface with ultrasonic waves or a laser. The vehicle height sensor 58 transmits the detected vehicle height (vehicle height sensor value) to the ECU 56 via, for example, a controller area network (CAN; Controller Area Network) (not shown). Further, the vehicle height sensor 58 and the ECU 56 may be connected to each other so as to be able to communicate with each other by a dedicated line. The vehicle height sensor 58 is an example of the vehicle height detection unit in the present embodiment.

The compressor unit 30 includes a compressor 36, a dryer 38, a throttle mechanism 40, a relief valve 42, an exhaust side filter 50, an intake side filter 52, and check valves 44 and 46. The operation of each configuration of the compressor unit 30 is controlled by the ECU 56 described later.

The compressor 36 is driven by a motor (not shown). When the compressor 36 operates, air is taken in from the outside through the intake side filter 52, and the compressed air is replenished to the air spring 12 and the air tank 26 through the main flow path 20.

The dryer 38 is located on the downstream side of the compressor 36 and removes the moisture of the taken-in air. Further, the throttle mechanism 40 includes an orifice 40a and a check valve 40b, and adjusts the passing speed of air from the dryer 38 to the main flow path 20.

Further, the air flowing out from the air spring 12 and the air tank 26 through the main flow path 20 is discharged through the exhaust side filter 50 when the relief valve 42 is in the valve open state. The relief valve 42 is, for example, a normally closed electromagnetic control valve that is closed by the urging force of a spring when the solenoid is in the non-energized state and is opened when the solenoid is in the energized state.

The vehicle height adjusting valves 14FR, 14FL, 14RR, and 14RL block or communicate the flow of air supplied and discharged by the compressor unit 30 between the main flow path 20 and the air spring 12 and the air tank 26 (with respect to the air spring 12). By changing the amount of air inflow), the vehicle height of the vehicle body (not shown) is adjusted. Hereinafter, when each vehicle height adjusting valve is not distinguished, it is simply referred to as "vehicle height adjusting valve 14". For example, when the compressor unit 30 sends the air taken in from the outside to the main flow path 20, the vehicle height adjusting valve 14 opens, and the air flows into the air spring 12 and the air tank 26 to increase the vehicle height. To rise. Further, when the compressor unit 30 does not send the air taken in from the outside to the main flow path 20, the vehicle height adjusting valve 14 is opened, and the air flows out from the air spring 12 and the air tank 26, so that the vehicle height is lowered. To do.

Each vehicle height adjusting valve 14 is a normally closed electromagnetic control valve that is closed by the urging force of a spring when the solenoid is in the non-energized state and is opened when the solenoid is in the energized state. .. Each vehicle height adjusting valve 14 is individually opened / closed controlled by an ECU 56 described later.

The ECU 56 is equipped with a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an SSD (Solid State Drive, flash memory), and the like, and has a hardware configuration using a normal computer. It has become. The ECU 56 acquires the detection results of the vehicle height sensor 58, the wheel speed sensor, the acceleration sensor, the steering angle sensor, etc. (not shown), the input value by the user, and the like via the CAN or the like. Further, the ECU 56 functions as a control unit that controls the spring constant switching valve 24, the vehicle height adjusting valve 14, and the compressor unit 30.

FIG. 2 is a block diagram showing an example of the functional configuration of the ECU 56 according to the present embodiment. As shown in FIG. 2, the ECU 56 includes an acquisition unit 151, a calculation unit 152, a determination unit 153, a switching determination unit 154, an output unit 155, a change unit 156, and a storage unit 150.

Each configuration of the acquisition unit 151, the calculation unit 152, the determination unit 153, the switching determination unit 154, the output unit 155, and the change unit 156 is realized by the CPU of the ECU 56 executing the program stored in the ROM. .. It should be noted that these configurations may be configured to be realized by a hardware circuit.

The storage unit 150 is a storage device such as a RAM or SSD. As shown in FIG. 2, the storage unit 150 of the present embodiment stores the upper limit value of the stroke amount, the lower limit value of the stroke amount, the vehicle height setting value, and the valve closing prohibition flag.

The vehicle height set value is a set value indicating the current vehicle height. In the present embodiment, the vehicle height setting values are, for example, three types of normal, high, and low. The vehicle height setting value is set by the user, for example, via an operation unit (not shown). Further, the vehicle height setting value may be changed according to the vehicle speed, road conditions, and the like. The vehicle height setting value in this embodiment is an example, and is not limited to this.

The valve closing prohibition flag is a flag indicating whether or not the spring constant switching valve 24 can be closed. For example, if the closing of the spring constant switching valve 24 is not prohibited, the valve closing prohibition flag is "0", and if the closing of the spring constant switching valve 24 is prohibited, the valve closing prohibition flag is "1". ". The valve closing prohibition flag is individually provided for each spring constant switching valve 24. The valve closing prohibition flag is set by the determination unit 153 described later.

The stroke amount is the length of the air spring 12 extending or contracting from the neutral position. Further, the upper limit value and the lower limit value of the stroke amount indicate the range of the stroke amount in which the differential pressure between the air tank 26 and the air spring 12 is within the allowable range even when the spring constant switching valve 24 is closed.

For example, when the stroke amount of the air spring 12 is equal to or more than the upper limit value or the lower limit value of the stroke amount and the spring constant switching valve 24 is closed, then when the air spring 12 returns to the neutral state, the air spring 12 side The amount of pressure fluctuation increases. In this case, the differential pressure between the inside of the air tank 26 and the inside of the air spring 12 becomes large, and the spring constant switching valve 24 does not move smoothly.

On the other hand, if the stroke amount of the air spring 12 is larger than the lower limit value of the stroke amount and within the range smaller than the upper limit value and the spring constant switching valve 24 is closed, even if the air spring 12 returns to the neutral state after that. , The amount of pressure fluctuation on the air spring 12 side is relatively small. In this case, the differential pressure between the inside of the air tank 26 and the inside of the air spring 12 is within the allowable range, and the state in which the spring constant switching valve 24 can be smoothly opened and closed is maintained.

FIG. 3 is a graph illustrating an example of the relationship between the stroke amount of the air spring 12 and the internal pressure of the air spring 12. The horizontal axis of the graph shown in FIG. 3 indicates the stroke amount (mm) of the air spring 12, and the vertical axis indicates the pressure (internal pressure) (Mpa) in the air spring 12. In the present embodiment, as shown in FIG. 3, the stroke amount when the air spring 12 is in the neutral state is "0", the contracted length (stroke amount) of the air spring 12 is a positive number, and the air spring 12 The length of extension (stroke amount) is represented by a negative number. Further, the stroke amount when the air spring 12 contracts is referred to as a bounce side stroke amount, and the stroke amount when the air spring 12 is extended is also referred to as a rebound side stroke amount.

As shown in FIG. 3, in general, the relationship between the stroke amount of the air spring 12 and the internal pressure of the air spring 12 is non-linear. For example, when the air spring 12 contracts, the fluctuation of the internal pressure of the air spring 12 becomes larger than when the air spring 12 expands by the same length. Therefore, when the internal pressure when the air spring 12 is in the neutral state is "1.1" and the fluctuation of the pressure by "0.2" up and down is set as the allowable range, the upper limit value of the stroke amount (bound side). The stroke amount) is "40", and the lower limit value of the stroke amount (stroke amount on the rebound side) is "-50". By setting the absolute value of the upper limit value and the absolute value of the lower limit value of the stroke amount to different values in this way, the permissible range of the stroke amount more in line with the characteristics of the air spring 12 can be determined. The stroke amount of the air spring 12 and the value of the internal pressure of the air spring 12 shown in FIG. 3 are examples, and are not limited thereto.

Further, since the value of the internal pressure when the air spring 12 is in the neutral state changes depending on the vehicle height set value, the upper limit value and the lower limit value of the stroke amount differ depending on the vehicle height setting. FIG. 3 shows a case where the vehicle height setting value is normal. When the vehicle height is set to high, the internal pressure in the neutral state becomes higher, and when the vehicle height is set to low, the internal pressure in the neutral state becomes lower. The storage unit 150 stores the upper limit value and the lower limit value of the stroke amount in association with each vehicle height set value.

Further, in general, the maximum stroke amount of each air spring 12 may differ between the front side and the rear side, so the upper limit value and the lower limit value of the stroke amount are the front wheel height adjusting portion (air spring 12FR, 12FL) and the rear. Different values may be set in the wheel height adjusting portions (air springs 12RR, 12RL). Further, the upper limit value and the lower limit value of the stroke amount may be set different values on the right side (air spring 12FR, 12RR) and the left side (air spring 12FL, 12RL) of the vehicle body.

The upper limit value of the stroke amount is an example of the first threshold value in the present embodiment, and the lower limit value of the stroke amount is an example of the second threshold value in the present embodiment. Further, the absolute value of the upper limit value of the stroke amount is an example of the first absolute value in the present embodiment, and the absolute value of the lower limit value of the stroke amount is an example of the second absolute value in the present embodiment.

Returning to FIG. 2, the acquisition unit 151 acquires various sensor values and the like transmitted via the CAN or a dedicated line or the like. More specifically, the acquisition unit 151 acquires the detection result of the vehicle height sensor 58 (vehicle height sensor value) and the detection result of the wheel speed sensor, the acceleration sensor, the steering angle sensor, etc. (not shown).

Further, the acquisition unit 151 acquires the state of supply of the control current to the spring constant switching valve 24 and the vehicle height adjusting valve 14. For example, the acquisition unit 151 acquires from the drive IC (not shown) whether the drive IC (not shown) turns the supply of the control current to the spring constant switching valve 24 in the ON state or the OFF state. The method of acquiring the control current supply state is not limited to this.

In addition, the acquisition unit 151 acquires the user's operation information transmitted from the operation unit (not shown). The operation unit (not shown) is, for example, an input button, a touch panel, or the like, and accepts an operation of changing the characteristics of the air spring 12 and an operation of changing the vehicle height set value by the user. The information acquired by the acquisition unit 151 is not limited to these.

The calculation unit 152 calculates the stroke amount of the air spring 12 from the vehicle height sensor value acquired by the acquisition unit 151. For example, the calculation unit 152 calculates a value obtained by subtracting the acquired vehicle height (vehicle height sensor value) from the vehicle height when the air spring 12 is in the neutral state as the stroke amount of the air spring 12. The stroke amount calculation method is not limited to this.

The determination unit 153 determines the open / closed state of the spring constant switching valve 24 for each spring constant switching valve 24, and determines whether or not the calculated stroke amount is within the range from the lower limit value to the upper limit value of the stroke amount. Make a decision.

More specifically, the determination unit 153 determines the open / closed state of each spring constant switching valve 24 from the state of supply of the control current to each spring constant switching valve 24 acquired by the acquisition unit 151. For example, the determination unit 153 determines that the spring constant switching valve 24 is in the closed state when the supply of the control current to the spring constant switching valve 24 is in the ON state. Further, the determination unit 153 determines that the spring constant switching valve 24 is in the open state when the supply of the control current to the spring constant switching valve 24 is in the OFF state.

Further, when the determination unit 153 determines that the spring constant switching valve 24 is in the valve open state, the stroke amount calculated by the calculation unit 152 is set to an upper limit value from the lower limit value of the stroke amount stored in the storage unit 150. Determine if it is within range. More specifically, since the upper limit value and the lower limit value of the stroke amount differ depending on the vehicle height set value, the determination unit 153 refers to the current vehicle height set value stored in the storage unit 150 and sets the vehicle height set value. The upper and lower limits of the associated stroke amount are compared with the calculated stroke amount.

The determination unit 153 prohibits (limits) the closing of the spring constant switching valve 24 when the calculated stroke amount is equal to or greater than the upper limit value of the stroke amount or equal to or less than the lower limit value of the stroke amount. In this case, the determination unit 153 sets, for example, "1" to the valve closing prohibition flag of the spring constant switching valve 24 of the storage unit 150. Further, the determination unit 153 does not prohibit (limit) the closing of the spring constant switching valve 24 when the calculated stroke amount is within a range larger than the lower limit value of the stroke amount and smaller than the upper limit value. In this case, the determination unit 153 sets, for example, "0" to the valve closing prohibition flag of the spring constant switching valve 24 of the storage unit 150. The method for prohibiting (restricting) closing the spring constant switching valve 24 is not limited to this.

The switching determination unit 154 determines the spring constant for each air spring 12 according to the detection results of various sensors acquired by the acquisition unit 151, the operation of changing the characteristics of the air spring 12 by the user, and the valve closing prohibition flag. Determine whether to switch.

For example, in the switching determination unit 154, when the acquisition unit 151 acquires an operation for changing the characteristics of the air spring 12 by the user, the valve closing prohibition flag for each spring constant switching valve 24 may be "0". If (that is, if valve closing is not prohibited), it is determined that the spring constant of the air spring 12 associated with the spring constant switching valve 24 is switched higher. Further, in the switching determination unit 154, when the acquisition unit 151 acquires an operation for changing the characteristics of the air spring 12 by the user, the valve closing prohibition flag for each spring constant switching valve 24 may be "1". If (that is, if valve closing is prohibited), it is determined that the spring constant of the air spring 12 associated with the spring constant switching valve 24 is not switched and the standard setting is maintained.

Further, the switching determination unit 154 may determine whether or not to switch the spring constant of the air spring 12 according to the vehicle speed and the like and the valve closing prohibition flag, not limited to the change operation by the user. For example, the switching determination unit 154 can determine that the spring constant is not switched as standard when the vehicle is running steadily, and can set the mode in which the riding comfort is prioritized. Further, the switching determination unit 154 determines that the spring constant is switched higher when the valve closing prohibition flag is "0" when the vehicle is turning or sudden acceleration / deceleration. When the spring constant becomes high, the mode gives priority to stabilizing the vehicle posture. The switching determination unit 154 determines from the detection results of the wheel speed sensor, acceleration sensor, steering angle sensor, etc. (not shown) acquired by the acquisition unit 151 whether the vehicle is running steadily or turning or suddenly accelerating or decelerating. Judgment shall be made.

Further, the conditions under which the switching determination unit 154 determines the switching of the spring constant are not limited to these. For example, if there is at least one spring constant switching valve 24 in which the valve closing prohibition flag is set to "1", the switching determination unit 154 does not switch the spring constants of all the air springs 12 and keeps the standard setting. You may judge.

The output unit 155 outputs a control signal according to the result of determining whether or not to switch the spring constant of the air spring 12 by the switching determination unit 154, thereby individually operating the opening / closing operation of each spring constant switching valve 24. Control. Specifically, when the switching determination unit 154 determines that the spring constant of the air spring 12 is switched to a high value, the output unit 155 outputs a control signal to a drive IC (not shown) to control the spring constant switching valve 24. Turn on the current supply. When the control current supply is turned on, the spring constant switching valve 24 is closed and the spring constant of the air spring 12 is increased.

Further, when the switching determination unit 154 determines that the spring constant of the air spring 12 is not switched high, that is, the standard setting is set, the output unit 155 does not output a control signal to a drive IC (not shown). In this case, the supply of the control current to the spring constant switching valve 24 remains in the OFF state, and the spring constant switching valve 24 maintains the valve open state. The method of controlling the opening / closing operation of the spring constant switching valve 24 by the output unit 155 is an example, and the method is not limited thereto.

When the acquisition unit 151 acquires the vehicle height setting value input by the user, the change unit 156 changes the vehicle height setting value stored in the storage unit 150. Further, the changing unit 156 may adopt a configuration in which the vehicle height setting value is changed according to the vehicle speed or the like.

Next, the air spring control process executed by the air spring control device 10 of the present embodiment configured as described above will be described. FIG. 4 is a flowchart showing an example of the procedure of the air spring control process according to the present embodiment. It is assumed that the processing of this flowchart is repeatedly executed at predetermined time intervals, for example, when the ignition power of the vehicle is turned on. In addition, the processing of this flowchart is executed regardless of whether the vehicle is stopped or running.

In the input process, the acquisition unit 151 acquires whether or not the user has changed the characteristics of the air spring 12 from an operation unit (not shown). Further, the acquisition unit 151 acquires the detection results of the wheel speed sensor, the acceleration sensor, and the steering angle sensor (not shown) (S1).

Next, the valve closing restriction process is executed (S2). FIG. 5 is a flowchart showing an example of the procedure of the valve closing restriction process according to the present embodiment.

First, the acquisition unit 151 acquires the presence or absence of power supply to each spring constant switching valve 24 from a drive IC (not shown) (S21). Further, the acquisition unit 151 acquires the detection result (vehicle height sensor value) of each vehicle height sensor 58 (S22).

The calculation unit 152 calculates the stroke amount of each air spring 12 from the vehicle height sensor value acquired by the acquisition unit 151 (S23).

The determination unit 153 determines whether or not each spring constant switching valve 24 is in the open state based on the presence or absence of power supply to each spring constant switching valve 24 acquired by the acquisition unit 151 (S24). When the supply of the control current to the spring constant switching valve 24 is in the OFF state, the determination unit 153 determines that the spring constant switching valve 24 is in the valve open state (S24 “Yes”).

When the spring constant switching valve 24 is in the valve open state, the determination unit 153 determines the current vehicle height set value stored in the storage unit 150 and the lower limit value of the stroke amount associated with the current vehicle height set value. Get the upper limit and. Then, the determination unit 153 determines whether or not the stroke amount of the air spring 12 associated with the spring constant switching valve 24 is within the range (within a predetermined range) from the lower limit value to the upper limit value of the stroke amount. (S25). For example, when the spring constant switching valve 24FR is in the valve open state and the current vehicle height setting value is "normal", the determination unit 153 determines that the stroke amount of the air spring 12FR is the lower limit value "-50" of the stroke amount. It is determined from the above whether or not it is within the range of the upper limit value "40".

When the determination unit 153 determines that the stroke amount of the air spring 12 is not within the range from the lower limit value to the upper limit value of the stroke amount (S25 “No”), the determination unit 153 sets “1” in the valve closing prohibition flag of the storage unit 150. By doing so, the closing of the spring constant switching valve 24 associated with the air spring 12 is prohibited (S26). For example, when the determination unit 153 determines that the stroke amount of the air spring 12FR is equal to or more than the upper limit value “40” or the lower limit value “-50” of the stroke amount, the spring constant switching valve 24FR is prohibited from closing. To do.

Further, the determination unit 153 determines that the spring constant switching valve 24 is in the closed state when the supply of the control current to the spring constant switching valve 24 is in the ON state (S24 “No”). In this case, the determination unit 153 sets the valve closing prohibition flag of the storage unit 150 to “0” so as not to limit the closing of the spring constant switching valve 24 associated with the air spring 12 (S27). ). Further, even when the determination unit 153 determines that the stroke amount of the air spring 12 is within the range larger than the lower limit value of the stroke amount and smaller than the upper limit value (S25 “Yes”), the valve closing prohibition flag of the storage unit 150 is also set. By setting "0" to, the closing of the spring constant switching valve 24 associated with the air spring 12 is not restricted (S27). Even if the valve closing prohibition flag is set to "1" by the valve closing prohibition processing executed up to the previous time, the judgment unit 153 sets the valve closing prohibition flag to "0" in the valve closing prohibition processing this time. Then, the prohibition of closing the spring constant switching valve 24 is released.

When the flow of the valve closing restriction process shown in FIG. 5 is completed, the flow returns to the flow of the air spring control process shown in FIG. 4, and the spring constant switching determination process is executed (S3).

In the spring constant switching determination process, the switching determination unit 154 determines whether or not the user has changed the characteristics of the air spring 12 acquired by the acquisition unit 151 in the process of S1, a wheel speed sensor, an acceleration sensor, a steering angle sensor, etc. (not shown). It is determined whether or not to switch the spring constant for each air spring 12 according to the detection result of.

For example, in the switching determination unit 154, when the acquisition unit 151 acquires an operation for changing the characteristics of the air spring 12 by the user, if the valve closing prohibition flag is "1", the spring constant of the air spring 12 is constant. It is judged that the standard setting is used without switching. Further, the switching determination unit 154 obtains the spring constant of the air spring 12 if the valve closing prohibition flag is "0" when the acquisition unit 151 acquires the operation of changing the characteristics of the air spring 12 by the user. Is judged to be switched high. Further, the switching determination unit 154 has acquired the non-acquisition that the acquisition unit 151 has acquired whether the vehicle is running steadily or is turning or suddenly accelerating or decelerating even when the user does not change the characteristics of the air spring 12. Judgment is made from the detection results of the wheel speed sensor, acceleration sensor, and steering angle sensor shown in the figure. When the switching determination unit 154 determines that the vehicle is turning or sudden acceleration / deceleration, if the valve closing prohibition flag is "0", the switching determination unit 154 determines that the spring constant is switched high.

Next, in the output process, the output unit 155 individually performs the opening / closing operation of each spring constant switching valve 24 according to the result of determining whether or not to switch the spring constant of the air spring 12 by the switching determination unit 154 of S3. (S4). For example, when the switching determination unit 154 determines that the spring constant of the air spring 12FR is switched to a high value, the output unit 155 outputs a control signal to a drive IC (not shown) to supply a control current to the spring constant switching valve 24FR. Is turned on. Further, when the switching determination unit 154 determines that the spring constant of the air spring 12FR is not switched high, that is, the standard setting is maintained, the output unit 155 does not output a control signal to the drive IC (not shown) and the spring constant switching valve. The valve open state of 24FR is maintained.

As described above, according to the air spring control device 10 of the present embodiment, the spring constant switching valve 24 is closed according to the stroke amount of the air spring 12 or the pressure in the air spring 12 or the air tank 26. By limiting the operation, the differential pressure between the inside of the air tank 26 and the inside of the air spring 12 is reduced, so that it is possible to prevent the spring constant switching valve 24 from not moving smoothly.

Further, according to the air spring control device 10 of the present embodiment, the spring constant switching valve 24 can be prevented from moving smoothly, so that the spring constant can be switched even if a spring having a smaller repulsive force is used. The valve 24 can be opened, and the spring constant switching valve 24 can be miniaturized.

Further, the air spring control device 10 of the present embodiment limits the closing operation of the spring constant switching valve 24 when the stroke amount of the air spring 12 is equal to or more than the upper limit value of the stroke amount or equal to or less than the lower limit value of the stroke amount. To do. Therefore, according to the air spring control device 10 of the present embodiment, it is possible to prevent the differential pressure between the inside of the air tank 26 and the inside of the air spring 12 from becoming higher than the permissible range in advance.

Further, according to the air spring control device 10 of the present embodiment, since the absolute value of the upper limit value of the stroke amount and the absolute value of the lower limit value of the stroke amount are different, the spring constant switching valve corresponding to the characteristics of the air spring 12 It is possible to control the opening / closing operation of the 24.

Further, the air spring control device 10 of the present embodiment sets the upper limit value of the stroke amount and the lower limit value of the stroke amount according to the vehicle height of the vehicle body adjusted by the vehicle height adjusting valve 14, that is, the current vehicle height set value. change. Therefore, according to the air spring control device 10 of the present embodiment, the opening / closing control of the spring constant switching valve 24FR is performed with higher accuracy in response to the change in the internal pressure at the neutral position of the air spring 12 due to the vehicle height adjustment. Can be done.

(Embodiment 2)
In the air spring control device 10 of the first embodiment, the valve closing operation of the spring constant switching valve 24 is limited according to the stroke amount of the air spring 12. The air spring control device 1010 of the present embodiment limits the valve closing operation of the spring constant switching valve 24 according to the pressure in the air tank 26.

FIG. 6 is a diagram showing an example of the configuration of the air spring control device 1010 according to the second embodiment. As shown in FIG. 6, the air spring control device 1010 of the present embodiment includes pressure sensors 32FR, 32FL, 32RR, and 32RL in addition to the same configuration as that of the first embodiment. Hereinafter, when each pressure sensor is not distinguished, it is simply referred to as "pressure sensor 32".

Each pressure sensor 32 is installed in each air tank 26 and can detect the pressure in each air tank 26. The pressure sensor 32 transmits the detected pressure to the ECU 56 via, for example, the CAN. Further, the pressure sensor 32 and the ECU 56 may be connected to each other so as to be able to communicate with each other by a dedicated line.

When the spring constant switching valve 24 is in the open state, the pressure in the air spring 12 and the pressure in the air tank 26 are equal to each other. Therefore, the installation position of the pressure sensor 32 is not limited to the inside of the air tank 26, and may be installed in the air spring 12 or the pipe 16. The pressure sensor 32 is an example of the pressure detection unit in this embodiment.

FIG. 7 is a block diagram showing an example of the functional configuration of the ECU 56 according to the present embodiment. As shown in FIG. 7, the ECU 56 includes an acquisition unit 1151, a determination unit 1153, a switching determination unit 154, an output unit 155, a change unit 156, and a storage unit 1150. The switching determination unit 154, the output unit 155, and the change unit 156 have the same functions as those in the first embodiment.

The storage unit 1150 of the present embodiment stores the upper limit value of the pressure, the lower limit value of the pressure, the vehicle height set value, and the valve closing prohibition flag. The vehicle height set value and the valve closing prohibition flag are the same as those in the first embodiment.

The upper and lower limits of the pressure are the air spring 12 and the air tank 26 in the valve open state in which the differential pressure between the air tank 26 and the air spring 12 is within the allowable range even when the spring constant switching valve 24 is closed. Indicates the range of pressure inside. In the example shown in FIG. 3, when the vehicle height setting value is "normal" and the air spring 12 is in the neutral state, the pressure (internal pressure) in the air spring 12 and the air tank 26 becomes "1.1". .. Further, in the present embodiment, as shown in FIG. 3, the permissible range is the fluctuation of the pressure by "0.2" up and down from the neutral state. In this case, the upper limit of the pressure is "1.3" and the lower limit of the pressure is "0.9".

Further, since the value of the internal pressure when the air spring 12 is in the neutral state changes depending on the vehicle height set value, the upper limit value and the lower limit value of the pressure differ depending on the vehicle height setting. The storage unit 1150 stores the upper limit value and the lower limit value of the pressure in association with each vehicle height set value.

Returning to FIG. 7, the acquisition unit 1151 acquires the detection result (pressure value) of the pressure in each air tank 26 from each pressure sensor 32 after having the function of the first embodiment.

Further, when the determination unit 1153 has the function of the first embodiment and determines that the spring constant switching valve 24 is in the valve open state, the pressure in the air tank 26 acquired by the acquisition unit 1151 is currently measured. It is determined whether or not the pressure is within the range from the lower limit value to the upper limit value of the pressure associated with the vehicle height set value of.

The determination unit 1153 prohibits the closing of the spring constant switching valve 24 when the pressure in the air tank 26 is equal to or higher than the upper limit value of the pressure or lower than the lower limit value of the pressure. In this case, the determination unit 1153 sets “1” in the valve closing prohibition flag of the spring constant switching valve 24 of the storage unit 1150. Further, the determination unit 1153 does not limit the closing of the spring constant switching valve 24 when the pressure in the air tank 26 is within a range larger than the lower limit value of the pressure and smaller than the upper limit value. In this case, the determination unit 1153 sets “0” in the valve closing prohibition flag of the spring constant switching valve 24 of the storage unit 1150.

Next, the process executed by the air spring control device 1010 of the present embodiment configured as described above will be described. The procedure of the air spring control process of the present embodiment is the same as the flowchart of the first embodiment described with reference to FIG. In the present embodiment, the content of the valve closing restriction process of S2 is different from that of the first embodiment. FIG. 8 is a flowchart showing an example of the procedure of the valve closing restriction process according to the present embodiment.

The process of acquiring the presence / absence of power supply to each spring constant switching valve 24 in S21 of FIG. 8 is the same as the process of the first embodiment shown in FIG.

Next, the acquisition unit 1151 acquires the detection result (pressure value) of the pressure in each air tank 26 from each pressure sensor 32 (S122).

Next, the determination unit 1153 determines whether or not each spring constant switching valve 24 is in the valve open state, as in S24 of the first embodiment.

When the spring constant switching valve 24 is in the valve open state (S24 “Yes”), the determination unit 1153 is associated with the current vehicle height set value stored in the storage unit 150 and the current vehicle height set value. Obtain the lower and upper limits of pressure.

Then, the determination unit 1153 determines whether or not the pressure (internal pressure) of the air tank 26 associated with the spring constant switching valve 24 is within the range from the lower limit value to the upper limit value of the pressure (S125).

When the determination unit 1153 determines that the pressure of the air tank 26 is out of the range of the upper limit value (outside the predetermined range) from the lower limit value of the pressure (S125 “No”), the spring constant switching valve 24FR is closed. Prohibit (S26). For example, when the spring constant switching valve 24FR is in the open state and the current vehicle height setting value is "normal", the determination unit 1153 determines that the pressure of the air tank 26 is equal to or higher than the upper limit value of the pressure "1.3". Alternatively, if it is determined that the lower limit value is "0.9" or less, the closing of the spring constant switching valve 24FR is prohibited.

Further, when the determination unit 1153 determines that the pressure of the air tank 26 is outside the range (within a predetermined range) larger than the lower limit value of the pressure and smaller than the upper limit value (S125 “Yes”), the spring constant switching valve 24 The valve closing of the valve is not restricted (S27). For example, when the spring constant switching valve 24FR is in the open state and the current vehicle height setting value is "normal", the judgment unit 1153 determines that the pressure of the air tank 26FR is higher than the lower limit value "0.9" of the pressure. If it is determined that the value is largely smaller than the upper limit value "1.3", the closing of the spring constant switching valve 24FR is not restricted.

Further, the determination unit 1153 does not limit the closing of the spring constant switching valve 24 when the determination result of S24 is "No", as in the first embodiment (S27).

When the flow of the valve closing restriction process shown in FIG. 8 is completed, the flow returns to the flow of the air spring control process shown in FIG. 4 and the spring constant switching determination process is executed as in the first embodiment (S3). The spring constant switching determination process of S3 and the output process of S4 are the same as those in the first embodiment.

As described above, the air spring control device 1010 of the present embodiment closes the spring constant switching valve 24 when the detected pressure is out of the predetermined range in the state where the spring constant switching valve 24 is opened. To limit. That is, in the present embodiment, the pressure fluctuation in the air spring 12 and the air tank 26 is not determined from the stroke amount, but the pressure is directly detected. Therefore, according to the air spring control device 1010 of the present embodiment, in addition to the effect of the first embodiment, it is possible to suppress the state in which the spring constant switching valve 24 does not move smoothly with higher accuracy. ..

Although the embodiments of the present invention have been illustrated above, the above-described embodiments and modifications are merely examples, and the scope of the invention is not intended to be limited. The above-described embodiment and modification can be implemented in various other forms, and various omissions, replacements, combinations, and changes can be made without departing from the gist of the invention. Further, the configuration and shape of each embodiment and each modification can be partially replaced.

10, 1010 ... Air spring control device, 12, 12FR, 12FL, 12RR, 12RL ... Air spring, 14, 14FR, 14FL, 14RR, 14RL ... Vehicle height adjustment valve, 16, 16FR, 16FL, 16RR, 16RL ... Pipe, 20 ... Main flow path, 24, 24FR, 24FL, 24RR, 24RL ... Spring constant switching valve, 26, 26FR, 26FL, 26RR, 26RL ... Air tank, 32, 32FR, 32FL, 32RR, 32RL ... Pressure sensor, 56 ... ECU, 58 , 58FR, 58FL, 58RR, 58RL ... Vehicle height sensor, 150, 1150 ... Storage unit, 151,1151 ... Acquisition unit, 152 ... Calculation unit, 153,1153 ... Judgment unit, 154 ... Switching judgment unit, 155 ... Output unit, 156 ... Change part.

Claims (5)

An air spring that is installed corresponding to the wheels of the vehicle body and operates according to the flow state of the working fluid,
A tank corresponding to the air spring and capable of inflow and outflow of the working fluid,
An on-off valve that is interposed between the air spring and the tank and can change the spring constant of the air spring by allowing or blocking the flow of the working fluid.
A control unit that limits the valve closing operation of the on-off valve according to the stroke amount of the air spring or the pressure in the air spring or the tank.
An air spring control device. Further provided with a vehicle height detection unit for detecting the vehicle height of the vehicle body,
The control unit calculates the stroke amount of the air spring from the detected vehicle height, and when the stroke amount is equal to or more than the first threshold value or equal to or less than the second threshold value smaller than the first threshold value. Limiting the valve closing operation of the on-off valve,
The air spring control device according to claim 1. The first absolute value of the stroke amount at which the air spring reaches the first threshold value from the neutral state is different from the second absolute value of the stroke amount at which the air spring reaches the second threshold value from the neutral state.
The air spring control device according to claim 2. A pressure detecting unit for detecting the pressure in the air spring or the tank is further provided.
The control unit limits the valve closing operation of the on-off valve when the detected pressure is out of a predetermined range in the state where the on-off valve is opened.
The air spring control device according to claim 1. Further provided with a vehicle height adjusting valve for adjusting the vehicle height of the vehicle body by changing the inflow amount of the working fluid with respect to the air spring.
The control unit changes the first threshold value and the second threshold value according to the vehicle height adjusted by the vehicle height adjusting valve.
The air spring control device according to claim 2 or 3.

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