JP6735196B2 - Vehicle suspension system - Google Patents

Description

The present invention relates to a vehicle suspension device that controls a damping force of a damper based on a vehicle state quantity calculated based on a wheel speed fluctuation amount.

As a damper used for a vehicle suspension, various damping force variable dampers (hereinafter sometimes referred to as DFV dampers) that variably control a damping force stepwise or steplessly have been developed. As a mechanism for making the damping force variable, for example, an MRF system in which a magneto-rheological fluid (MRF) is used as hydraulic fluid and the viscosity of MRF is controlled by a magnetic fluid valve provided on a piston It has been known.

In Patent Document 1, a basic input amount of a vehicle (an input amount received by a wheel from a road surface or the like) is calculated based on a wheel speed fluctuation detected by a wheel speed sensor, and the calculated basic input amount is expressed as a vehicle model (representing vehicle behavior. ) Is input to calculate the state quantity of the vehicle, and the damping force control of the damping force variable damper is performed based on the calculated state quantity of the vehicle.

JP, 2014-008884, A

However, in the vehicle suspension device according to Patent Document 1, when the load capacity of the vehicle changes, the change in the load capacity is fed back without using the load sensor to control the damping force of the damping force variable damper. Is neither disclosed nor suggested. Therefore, there is room for improvement in the vehicle suspension device according to Patent Document 1 in that the ride comfort is kept good without using the load sensor even when the load capacity changes.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a vehicle suspension device that can maintain a good riding comfort without using a load sensor even when the vehicle load changes. To do.

In order to solve the above problems, the present invention is a vehicle suspension device including a damping force variable damper that is provided on at least a rear wheel of a vehicle and is capable of adjusting a damping force based on an input signal. A wheel speed sensor that detects a wheel speed of a wheel, a basic input amount calculation unit that calculates a basic input amount of the vehicle based on a variation of the wheel speed detected by the wheel speed sensor, and a vehicle that represents the behavior of the vehicle Based on a state quantity calculator that calculates the state quantity of the vehicle by inputting the basic input quantity to a model, and the front-back difference of the wheel speed detected by the calculated state quantity of the vehicle and the wheel speed sensor. And a control unit that controls the damping force of the damping force variable damper.

In the present invention, the control unit performs the damping force control of the damping force variable damper based on the vehicle state amount calculated by the state amount calculation unit and the front-back difference of the wheel speed detected by the wheel speed sensor.
According to the research conducted by the present inventors, it was found that the front-rear difference in wheel speed has a predetermined correlation with the loading amount. Therefore, in the present invention, when the damping force control of the damping force variable damper is performed, the loading amount based on the difference between the front and rear wheel speeds is referred to as an input signal in addition to the state amount of the vehicle.

According to the present invention, the damping force control of the damping force variable damper is performed based on the front-back difference of the wheel speed that can be regarded as the loading amount in addition to the state amount of the vehicle. Therefore, even when the loading amount of the vehicle changes, the load sensor It is possible to maintain a good ride comfort without using.

According to the present invention, it is possible to obtain a vehicle suspension device that can maintain a good riding comfort without using a load sensor even when the load capacity of a vehicle changes.

1 is a block diagram showing a schematic configuration of a vehicle suspension device according to an embodiment of the present invention. 6 is a flowchart showing a damping force control procedure by the vehicle suspension device. It is explanatory drawing showing the correlation of the front-back difference of a wheel speed, and a loading amount. FIG. 9 is an explanatory diagram illustrating an example of a map referred to when calculating a control compensation gain according to a change in a load amount.

Hereinafter, a vehicle suspension device according to the present invention will be described in detail with reference to the drawings, taking an example in which the device is applied to a four-wheeled vehicle.

[Configuration of vehicle suspension device 11 according to the present invention]
FIG. 1 is a block diagram showing a schematic configuration of a vehicle suspension device 11 according to an embodiment of the present invention. In FIG. 1, the elements related to the four wheels 13 are differentiated by adding numerical suffixes to the front and rear and left and right. That is, for example, the subscript (FR) for the front right wheel 13, the subscript (FL) for the front left wheel 13, the subscript (RR) for the rear right wheel 13, the subscript (RL) for the rear left wheel 13, Each is attached. Further, when collectively referring to each of the elements related to the four wheels 13, the subscripts are omitted.

As shown in FIG. 1, a vehicle suspension device 11 according to an embodiment of the present invention is provided on a wheel 13 of a vehicle (four-wheeled vehicle) 10 and has a coil spring 14 and a damping force variable damper (DFV damper) 15. It is configured to include a suspension 16 and a damper control ECU 17 (details will be described later). The wheels 13 are suspended on the vehicle body (not shown) of the vehicle 10 via suspensions 16.
The vehicle 10 is, for example, a front-wheel drive vehicle in which an engine is mounted on the front of the vehicle body and front wheels are drive wheels.
Although not particularly limited, the DFV damper 15 is, for example, a monotube type (de-carbonate type), and has a known configuration that adopts the MRF type.

Various sensors belonging to the input system are connected to the damper control ECU 17 via a communication medium 19 such as CAN. Examples of various sensors belonging to the input system include a wheel speed sensor 21, a vehicle speed sensor 23, a steering angle sensor 25, a lateral G sensor 27, and a yaw rate sensor 29.
The wheel speed sensors 21FR, 21FL, 21RR, 21RL detect the rotation speeds of the wheels 13FR, 13FL, 13RR, 13RL, respectively. The vehicle speed sensor 23 detects the speed of the vehicle body (vehicle speed). The steering angle sensor 25 detects a steering angle of a steering wheel (steering member) (not shown). The lateral G sensor 27 detects the lateral acceleration of the vehicle body. The yaw rate sensor 29 detects the yaw rate of the vehicle body. The detection values of the various sensors 21, 23, 25, 27, 29 belonging to these input systems are sent to the damper control ECU 17 via the communication medium 19.

The suspension 16 (including the DFV damper 15) belonging to the output system is connected to the damper control ECU 17. The damper control ECU 17 is configured by a microcomputer including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like.
This microcomputer reads and executes programs and data stored in the ROM, and controls the damping force of the DFV damper 15 based on the difference between the front and rear wheel speeds that the damper control ECU 17 can regard as the vehicle state amount and the load amount. It operates so as to perform execution control relating to various functions including the function of performing.

In order to realize the above-mentioned damping force control function, the damper control ECU 17 is configured to include an acquisition unit 31, a basic input amount calculation unit 33, a state amount calculation unit 35, a determination unit 37, and a control unit 39.

The acquisition unit 31 has a function of acquiring detection values of various sensors 21, 23, 25, 27, 29 belonging to the input system.

The basic input amount calculation unit 33 uses the well-known formula 1 (see paragraph 0035 of JP-A-2014-8884) on the basis of the fluctuation ΔVw of the wheel speed detected by the wheel speed sensor 21 of the vehicle 10. It has a function of calculating the unsprung load u1 which is the basic input amount for each of the wheels 13FR, 13FL, 13RR, 13RL.
u1=k·ΔVw (Formula 1)
However, k is a proportional constant.

The state quantity calculation unit 35 inputs the calculated basic input quantity into a known vehicle model representing the behavior of the vehicle 10 (see "One-wheel model 38" described in paragraph 0038 of JP-A-2014-8884). Has a function of calculating the state quantity (the sprung speed and the stroke speed of the suspension 16) of the vehicle 10 for each of the wheels 13FR, 13FL, 13RR, 13RL.

The determination unit 37 has a function of determining whether or not the vehicle 10 is traveling at a constant speed and straight ahead based on the vehicle speed detected by the vehicle speed sensor 23 and the steering angle detected by the steering angle sensor 25. ..

When it is determined that the vehicle 10 is traveling steadily at a constant speed and straight ahead, the control unit 39 determines the front-back difference between the calculated state quantity of the vehicle 10 and the wheel speed detected by the wheel speed sensor 21. Based on the above, it has a function of controlling the damping force of the DFV damper 15. In addition, when it is determined that the vehicle 10 is traveling steadily at a constant speed and in a straight line, the damping force control of the DFV damper 15 is performed based on the difference between the front and rear wheel speeds (loading amount). Is based on the fact that in a traveling scene involving acceleration/deceleration or a traveling scene involving a curved road, the correlation of the loading amount with respect to the front-rear difference in wheel speed is inferior to that in a steady traveling scene.

[Damping force control procedure by vehicle suspension device 11]
Next, a damping force control procedure by the vehicle suspension device 11 according to the embodiment of the present invention will be described with reference to FIGS. 2 to 4. FIG. 2 is a flowchart showing a damping force control procedure by the vehicle suspension device 11. FIG. 3 is an explanatory diagram showing the correlation between the front-rear difference in wheel speed and the loading amount. FIG. 4 is an explanatory diagram illustrating an example of a map that is referred to when calculating the control compensation gain according to the change in the load amount.

In step S11 shown in FIG. 2, the acquisition unit 31 of the damper control ECU 17 acquires the detection values of the various sensors 21, 23, 25, 27, 29 belonging to the input system.

In step S12, the basic input amount calculator 33 of the damper control ECU 17 applies the unsprung load u1 that is the basic input amount of the vehicle 10 to each wheel 13FR, based on the wheel speed variation ΔVw detected by the wheel speed sensor 21. It is calculated for each of 13FL, 13RR, and 13RL.

In step S13, the state quantity calculation unit 35 of the damper control ECU 17 inputs the basic input quantity calculated in step S12 to the vehicle model representing the behavior of the vehicle 10 so that the state quantity of the vehicle 10 (sprung speed and suspension 16). Stroke speed) of each wheel 13FR, 13FL, 13RR, 13RL is calculated.

In step S14, the determination unit 37 of the damper control ECU 17 determines whether or not the vehicle 10 is traveling at a constant speed based on whether or not the time differential value of the vehicle speed detected by the vehicle speed sensor 23 is less than a predetermined threshold value. To do. The determination unit 37 determines that the vehicle 10 is traveling at a constant speed when the time differential value of the vehicle speed is less than a predetermined threshold value.

As a result of the determination in step S14, when it is determined that the vehicle 10 is not traveling at a constant speed (“No” in step S14), the damper control ECU 17 jumps the process flow to step S17.
On the other hand, as a result of the determination in step S14, if it is determined that the vehicle 10 is traveling at a constant speed (“Yes” in step S14), the damper control ECU 17 shifts the processing flow to the next step S15. Let go.

In step S15, the determination unit 37 of the damper control ECU 17 determines whether the vehicle 10 is traveling straight ahead based on whether the time differential value of the steering angle detected by the steering angle sensor 25 is less than a predetermined threshold value. judge. The determination unit 37 determines that the vehicle 10 is traveling straight when the time differential value of the steering angle is less than a predetermined threshold value.

As a result of the determination in step S15, when it is determined that the vehicle 10 is not traveling straight ahead (“No” in step S15), the damper control ECU 17 jumps the processing flow to step S17.
On the other hand, as a result of the determination in step S15, when it is determined that the vehicle 10 is traveling straight ahead (“Yes” in step S15), the damper control ECU 17 advances the processing flow to the next step S16. Let

In step S16, the control unit 39 of the damper control ECU 17 determines whether the vehicle 10 is traveling at a constant speed and straight ahead in a steady state. With reference to the correlation with the amount, the integrated amount according to the front-back difference in wheel speed (front wheel speed-rear wheel speed) is estimated.

In step S17, if the control unit 39 of the damper control ECU 17 determines that the vehicle 10 is not traveling steadily (either one of constant speed traveling and straight traveling), it is determined in step S13. The damping force control of the DFV damper 15 is performed based on the state quantity of the vehicle 10 calculated in. After that, the damper control ECU 17 returns the flow of processing to step S11 to sequentially perform the following processing. The damping force control based on the state quantity of the vehicle 10 in step S17 is the same as the existing technology.

When it is determined in step S18 that the vehicle 10 is traveling steadily (constant speed and traveling straight), the control unit 39 of the damper control ECU 17 of the vehicle 10 calculated in step S13. The damping force control of the DFV damper 15 is performed based on the state amount and the loading amount estimated based on the front-back difference of the wheel speeds in step S16.
In practice, the control unit 39 of the damper control ECU 17 controls the damping force control amount of the DFV damper 15 based on the state amount of the vehicle 10 and the control compensation corresponding to the load amount estimated based on the front-back difference of the wheel speeds. Multiply the gain (see, for example, FIG. 4). Accordingly, the control unit 39 obtains the damping force control amount of the DFV damper 15 after the load amount compensation. The control unit 39 controls the damping force of the DFV damper 15 by using the damping force control amount of the DFV damper 15 after the compensation of the load amount thus obtained.
After that, the damper control ECU 17 returns the flow of processing to step S11 to sequentially perform the following processing. The gist of the present invention is the damping force control based on the state amount of the vehicle 10 and the front-back difference (loading amount) of the wheel speed in step S18.

[Operational Effects of Vehicle Suspension Device 11]
Next, operation effects of the vehicle suspension device 11 according to the embodiment of the present invention will be described.
The vehicle suspension device 11 according to the first aspect (corresponding to claim 1) is provided on at least the rear wheels 13RR, 13RL of the vehicle 10, and the damping force variable dampers 15RR, 15RL capable of adjusting the damping force based on an input signal. Equipped with. However, the front wheels 13FR and 13FL of the vehicle 10 may also be provided with the damping force variable dampers 15FR and 15FL.
The vehicle suspension device 11 based on the first aspect includes wheel speed sensors 21FR, 21FL, 21RR, 21RL for detecting the wheel speeds of the wheels 13FR, 13FL, 13RR, 13RL of the vehicle 10, and wheel speed sensors 21FR, 21FL. , 21RR, 21RL, and a basic input amount calculation unit 33 that calculates the unsprung load u1 that is the basic input amount of the vehicle 10 based on the variation ΔVw of the wheel speed, and a basic input to the vehicle model that represents the behavior of the vehicle 10. By inputting the amount (unsprung load u1), the state quantity calculation unit 35 that calculates the state quantity (the sprung speed and the stroke speed of the suspension 16) of the vehicle 10, and the calculated state quantity and the wheel speed of the vehicle 10 A control unit 39 that controls the damping force of the damping force variable dampers 15RR and 15RL based on the front-rear difference (loading amount).

According to the vehicle suspension device 11 based on the first aspect, the damping force control of the damping force variable dampers 15RR, 15RL is performed based on not only the state amount of the vehicle 10 but also the front-back difference of the wheel speed that can be regarded as the loading amount. Even when the load capacity of the vehicle 10 changes, the riding comfort can be maintained well without using the load sensor.

Further, the vehicle suspension device 11 according to the second aspect (corresponding to claim 2) has a difference in front and rear wheel speeds in a traveling scene involving acceleration/deceleration or in a traveling scene involving a curved road as compared with a steady traveling scene. It was created based on the new finding that the correlation of loading capacity is poor.
That is, the vehicle suspension device 11 based on the second aspect is the vehicle suspension device 11 based on the first aspect, and includes a vehicle speed sensor 23 that detects the vehicle speed of the vehicle 10 and steering of a steering member included in the vehicle 10. Based on the steering angle sensor 25 that detects the angle, the vehicle speed detected by the vehicle speed sensor 23, and the steering angle detected by the steering angle sensor 25, it is determined whether or not the vehicle 10 is traveling at a constant speed and straight ahead. The determination part 37 which determines is further provided.
When the determination unit 37 determines that the vehicle 10 is traveling steadily, the control unit 39 controls the damping force of the damping force variable dampers 15RR and 15RL based on the difference in front and rear (wheel load) of the wheel speeds. To do.

In the vehicle suspension device 11 based on the second aspect, in a traveling scene involving acceleration/deceleration (in which the correlation of the loading amount with respect to the front-back difference of the wheel speed is inferior to that in a steady traveling scene) or a traveling scene involving a curved road, The damping force control of the DFV damper 15 based on the difference between the front and rear wheel speeds (loading amount) is not performed.

According to the vehicle suspension device 11 based on the second aspect, the damping force control of the DFV damper 15 based on the difference between the front and rear wheel speeds (loading amount) can be performed with high accuracy while suppressing an error.

Further, the vehicle suspension device 11 based on the third aspect (corresponding to claim 3) appropriately controls the damping force of the DFV damper 15 when the load balance in the left-right direction (width direction) of the vehicle 10 is different. It was created with the aim of doing so.
That is, in addition to the configuration of the vehicle suspension device 11 based on the first aspect , the vehicle suspension device 11 according to the third aspect also includes the control unit 39 based on the state amount of the vehicle 10 and the left/right difference in wheel speed. The damping force control of the damping force variable dampers 15RR and 15RL is performed.

According to the vehicle suspension device 11 based on the third aspect, the damping force control of the damping force variable dampers 15RR and 15RL is independently performed based on the left and right difference in wheel speed in addition to the state quantity of the vehicle 10. Even when the load balance in the left-right direction (width direction) of the vehicle 10 changes, it is possible to maintain good riding comfort without using a load sensor.

[Other Embodiments]
The embodiment described above shows an example of embodying the present invention. Therefore, the technical scope of the present invention should not be limitedly interpreted by this. This is because the present invention can be implemented in various forms without departing from the gist or the main features thereof.

For example, in the description of the embodiment of the present invention, the damping force variable damper has been described by exemplifying the MRF type damper, but the present invention is not limited to this example. The damping force variable damper may be of any type as long as the damping force can be variably controlled stepwise or steplessly.

10 Vehicle 11 Vehicle Suspension Device 13 Wheel 15 Damping Force Variable Damper 21 Wheel Speed Sensor 23 Vehicle Speed Sensor 25 Steering Angle Sensor 33 Basic Input Quantity Calculator 35 State Quantity Calculator 37 Judgment Section 39 Control Section

Claims (3)

A suspension device for a vehicle, which is provided at least on a rear wheel of a vehicle and includes a damping force variable damper capable of adjusting a damping force based on an input signal,
A wheel speed sensor for detecting the wheel speed of each wheel provided in the vehicle,
A basic input amount calculation unit that calculates a basic input amount of the vehicle based on a change in wheel speed detected by the wheel speed sensor,
A state quantity calculation unit that calculates the state quantity of the vehicle by inputting the basic input quantity to a vehicle model representing the behavior of the vehicle,
A control unit that performs damping force control of the damping force variable damper based on the front-back difference of the wheel speed detected by the calculated state quantity of the vehicle and the wheel speed sensor,
A vehicle suspension device comprising: The vehicle suspension device according to claim 1, wherein
A vehicle speed sensor for detecting the vehicle speed of the vehicle,
A steering angle sensor for detecting a steering angle of a steering member provided in the vehicle,
Based on the vehicle speed detected by the vehicle speed sensor and the steering angle detected by the steering angle sensor, a determination unit for determining whether or not the vehicle is traveling at a constant speed and straight ahead, further comprising:
The control unit performs a damping force control of the damping force variable damper based on the front-back difference of the wheel speed when the determination unit determines that the vehicle is traveling normally. Suspension system for vehicles. The vehicle suspension device according to claim 1, wherein
The vehicle suspension characterized in that the control unit controls the damping force of the damping force variable damper based on the calculated state quantity of the vehicle and the left-right difference between the wheel speeds detected by the wheel speed sensor. apparatus.

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