Damping force control device

Abstract

To provide a damping force control device that can suppress the occurence of noise of a shock absorber.SOLUTION: A damping force control device controls damping force between a shock absorber interposed between a wheel of a vehicle and a vehicle body of the vehicle. The damping force control device includes: an acquisition unit configured to acquire the physical amount related to motion of the vehicle and an outside air temperature outside the vehicle; and a damping force control unit configured to perform a first damping force control for controlling damping force based on the physical amount when the outside air temperature is a temperature threshold or higher and to perform a second damping force control for, when the outside air temperature is below the temperature threshold, setting damping force to a value greater than the lower limit of the range within the damping force that can be set by the first damping force control.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a damping force control device. [Background technology]

[0002] There is a damping force control device that is provided in a vehicle and controls the damping force of a shock absorber of a suspension system, thereby improving ride comfort and driving stability. For example, a damping force control device that estimates the temperature of a shock absorber and controls the damping force based on the estimation result is known (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3042280 Summary of the Invention [Problem to be solved by the invention]

[0004] In shock absorbers, when the temperature of the hydraulic oil drops, the viscosity of the hydraulic oil increases, and abnormal noise may occur due to the movement of the hydraulic oil as the shock absorber operates. Patent Document 1 does not disclose measures to prevent abnormal noise when the temperature of the shock absorber drops.

[0005] One of the problems to be solved by the present invention is to provide a damping force control device capable of suppressing the generation of abnormal noise in a shock absorber. [Means for solving the problem]

[0006] The damping force control device of the present invention is a damping force control device that controls the damping force of a shock absorber interposed between a wheel of a vehicle and a body of the vehicle, and includes an acquisition unit that acquires a physical quantity related to the movement of the vehicle and an outside air temperature of the vehicle, and a damping force control unit that executes a first damping force control that controls the damping force based on the physical quantity when the outside air temperature is equal to or higher than a temperature threshold, and executes a second damping force control that sets the damping force within a range of the damping force that can be set by the first damping force control to a value greater than the lower limit value of the range when the outside air temperature is less than the temperature threshold. Effect of the Invention

[0007] According to the damping force control device of the present invention, the generation of abnormal noise in the shock absorber can be suppressed. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram illustrating a schematic configuration of an example of a vehicle according to an embodiment. [Diagram 2] FIG. 2 is a schematic diagram showing a schematic configuration of an example of a suspension device in a vehicle according to an embodiment. [Diagram 3] FIG. 3 is a functional block diagram of an example control device of a vehicle according to an embodiment. [Figure 4] FIG. 4 is a flowchart illustrating an example of a damping force control process executed by the control device according to the embodiment. [Diagram 5] FIG. 5 is a flowchart showing an example of the stop / run determination process in the damping force control process according to the embodiment. [Figure 6] FIG. 6 is a flowchart showing an example of a low-temperature response control necessity determination process in the damping force control process according to the embodiment. [Figure 7] FIG. 7 is a flowchart showing an example of a minimum outside air temperature update process in the damping force control process according to the embodiment. [Figure 8] FIG. 8 is a flowchart showing an example of the control setting process in the damping force control process according to the embodiment. [Figure 9] FIG. 9 is a timing chart showing an example of the damping force control process according to the embodiment. [Figure 10] FIG. 10 is a diagram showing an example of the relationship between the vehicle speed and the control current in the low-temperature response control of the damping force control process according to the embodiment. [Figure 11] FIG. 11 is a diagram showing an example of the relationship between the vehicle speed and the control current in the low-temperature response control of the damping force control process according to the first modified example of the embodiment. [Figure 12] FIG. 12 is a diagram showing an example of the relationship between the vehicle speed and the control current in the low-temperature response control of the damping force control process according to the second modified example of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments will be described in detail with reference to the drawings. Note that the present invention is not limited to these embodiments. The following embodiments include similar components. The similar components are given common reference numerals, and duplicated descriptions will be omitted.

[0010] FIG. 1 is a schematic diagram showing a schematic configuration of an example of a vehicle 1 according to an embodiment. In this embodiment, the vehicle 1 may be, for example, an automobile (internal combustion engine automobile) using an internal combustion engine (engine, not shown) as a drive source, an automobile (electric automobile, fuel cell automobile, etc.) using an electric motor (motor, not shown) as a drive source, or an automobile (hybrid automobile) using both of them as drive sources. The vehicle 1 may be equipped with various transmissions and various devices (systems, parts, etc.) required to drive the internal combustion engine or the electric motor. The type, number, layout, etc. of the device related to the drive of the wheels 3 in the vehicle 1 may be set in various ways. In this embodiment, as an example, the vehicle 1 is a four-wheeled vehicle (four-wheeled automobile) and has two front wheels 3F on the left and right and two rear wheels 3R ​​on the left and right. In FIG. 1, the front (direction Fr) in the vehicle longitudinal direction is the left side.

[0011] In this embodiment, as an example, the vehicle control system 100 of the vehicle 1 includes a control device 10, a steering device 11, a steering sensor 12, a detection sensor 13, a temperature sensor 14, etc. The vehicle control system 100 also includes a suspension device 4, a rotation sensor 5, a torque sensor 6, etc. corresponding to each of the two front wheels 3F, and also includes a suspension device 4, a rotation sensor 5, a torque sensor 6, etc. corresponding to each of the two rear wheels 3R.

[0012] Fig. 2 is a schematic diagram showing a schematic configuration of an example of the suspension device 4 in the vehicle 1 according to the embodiment. As shown in Fig. 2, the part of the vehicle 1 on the vehicle body 2 side with respect to the suspension device 4 is the sprung part 2a (Fig. 2), and the part of the vehicle 1 on the wheel 3 side with respect to the suspension device 4 is the unsprung part 2b (Fig. 2).

[0013] 1 and 2, vehicle 1 includes basic components as vehicle 1, but only the components related to vehicle control system 100 and the control related to the components will be described here. Wheels 3 are used as a general term for the two front wheels 3F and the two rear wheels 3R. The vertical relative speed of the wheels 3 of vehicle 1 relative to the body 2 of vehicle 1 is also referred to as stroke speed. The stroke speed is also the relative speed between the sprung portion 2a and the unsprung portion 2b.

[0014] The control device 10 receives signals and data from each part of the vehicle control system 100 via a network such as a CAN (Controller Area Network), and controls each part of the vehicle control system 100 and executes various calculations. In this embodiment, the control device 10 is an example of a damping force control device. The control device 10 is configured as a computer and includes an arithmetic processing unit (microcomputer, ECU (Electronic Control Unit), etc., not shown), a storage unit 10e (e.g., ROM (Read Only Memory), RAM (Random Access Memory), flash memory, etc., see FIG. 3), etc. The arithmetic processing unit can read a program stored (installed) in the non-volatile storage unit 10e (e.g., ROM, flash memory, etc.), execute arithmetic processing according to the program, and function (operate) as each part shown in FIG. 3. The storage unit 10e can store data (tables (data groups), functions, etc.) used in various calculations related to the control, calculation results (including values ​​during the calculation), etc.

[0015] The control device 10 controls the damping force of the shock absorber 4b. The damping force control includes normal control and low-temperature response control. The normal control controls the damping force based on a physical quantity related to the motion of the vehicle 1. The low-temperature response control sets the damping force to a high damping force when the outside air temperature of the vehicle 1 is below a threshold value.

[0016] The memory unit 10e stores control information 121. The control information 121 includes an outside air temperature detected by the temperature sensor 14. The control information 121 also includes a minimum outside air temperature, which is the minimum temperature among the outside air temperatures detected by the temperature sensor 14. The control information 121 also includes a low temperature response control necessity flag. A "0" in the low temperature response control necessity flag indicates that low temperature response control is necessary, and a "1" in the low temperature response control necessity flag indicates that low temperature response control is not necessary.

[0017] The steering device 11 includes, for example, a steering wheel, and steers (turns) the two front wheels 3F. The steering sensor 12 detects the steering angle (steering angle, turning angle, steering angle) of the front wheels 3F, and outputs steering angle data indicating the detected steering angle.

[0018] The detection sensor 13 detects a physical quantity related to the motion of the vehicle 1 (vehicle body 2). For example, the detection sensor 13 includes a yaw rate sensor that detects the yaw rate of the vehicle 1 (vehicle body 2) and outputs the detected yaw rate, and an acceleration sensor that detects the acceleration of the vehicle 1 (vehicle body 2) and outputs the detected acceleration. The acceleration of the vehicle 1 (vehicle body 2) includes at least one (for example, all of) the acceleration in the vertical direction of the vehicle 1 (vehicle body 2), the acceleration in the front-rear direction of the vehicle 1 (vehicle body 2), and the acceleration in the lateral direction (width direction) of the vehicle 1 (vehicle body 2). The yaw rate and acceleration are examples of physical quantities related to the motion of the vehicle 1 (vehicle body 2).

[0019] The rotation sensor 5 can output a signal according to the speed (rotation speed, angular velocity, number of rotations, rotation state) related to the rotation of each of the four wheels 3. The control device 10 can calculate the speed (vehicle speed) of the vehicle 1 from the detection result of the rotation sensor 5. Note that, in addition to the rotation sensor 5 for the wheels 3, a rotation sensor (not shown) that detects the rotation of a crankshaft, an axle, etc. may be provided, and the control device 10 may obtain the speed of the vehicle 1 from the detection result of this rotation sensor.

[0020] The torque sensors 6 are provided corresponding to the four wheels 3, respectively, and detect the rotational torque input to each wheel 3.

[0021] The temperature sensor 14 detects the temperature (also referred to as outside air temperature) of the vehicle 1 (air outside the vehicle 1) and outputs the detected outside air temperature to the control device 10. The outside air temperature detected by the temperature sensor 14 is stored in the memory unit 10e as control information 121. In detail, the outside air temperature detected by the temperature sensor 14 is stored in the memory unit 10e as control information 121.

[0022] The outputs of the above sensors are also used for operations (processing) executed by the vehicle 1 other than the damping force control processing, which will be described later.

[0023] FIG. 2 is a schematic diagram showing a schematic configuration of an example of a suspension device 4 in a vehicle according to an embodiment. As shown in FIG. 2, the suspension device 4 is interposed between the wheels 3 and the vehicle body 2, and suppresses the transmission of vibrations and impacts from the road surface to the vehicle body. The suspension device 4 has a coil spring 4a and a shock absorber 4b. The shock absorber 4b can electrically control (adjust) a damping force (damping characteristics). Specifically, the shock absorber 4b has an actuator 4bb that operates based on an input current (also called a control current). The actuator 4bb can change the opening degree of an orifice provided in a piston of the shock absorber 4b, or change the opening degree between a valve body and a valve seat. The actuator 4bb is, for example, a solenoid valve, but is not limited thereto. Thereby, the amount of hydraulic oil flowing between two hydraulic oil chambers partitioned by a piston in the shock absorber 4b is controlled, and the damping force of the shock absorber 4b is adjusted. The suspension device 4 is provided on each of the four wheels 3 (two front wheels 3F and two rear wheels 3R), and the control device 10 can control the damping force of each of the four wheels 3. The control device 10 can control the four wheels 3 so that their damping forces are different from one another. In detail, in order to control the damping force (=damping coefficient x stroke speed) of each shock absorber 4b, the damping coefficient is controlled. More specifically, the damping coefficient is controlled by controlling the current flowing through the actuator 4bb of the shock absorber 4b.

[0024] The above-described configuration of the vehicle control system 100 is merely an example, and can be modified in various ways. Known devices can be used as the individual devices constituting the vehicle control system 100. Each component of the vehicle control system 100 can be shared with other components.

[0025] Specifically, the control device 10 can function (operate) as an acquisition unit 10a, a calculation unit 10b, a timing unit 10c, a damping force control unit 10d, and the like, as shown in Fig. 3, by cooperation between hardware and software (programs), for example. That is, the program can include, for example, modules corresponding to each block except for the memory unit 10e shown in Fig. 3. However, this is not limited to this. For example, the various functional modules such as the acquisition unit 10a, the calculation unit 10b, the timing unit 10c, and the damping force control unit 10d can also be realized by independent hardware.

[0026] The acquisition unit 10a acquires, from the various sensors described above, physical quantities related to the motion of the vehicle 1. For example, the physical quantities include at least one of the speed of the wheels 3 according to the rotation of the wheels 3, the vertical acceleration of the vehicle 1 (body 2), the longitudinal acceleration of the vehicle 1 (body 2), the lateral acceleration of the vehicle 1 (body 2), the yaw rate of the vehicle 1, the steering angle of the wheels 3, the steering angular velocity of the wheels 3, and the rotational torque of the wheels 3.

[0027] Moreover, the acquisition unit 10a acquires (receives) the temperature of the outside air of the vehicle 1 from the temperature sensor 14.

[0028] As an example, the calculation unit 10b receives predetermined data (input data) acquired by the acquisition unit 10a. The calculation unit 10b calculates a target damping coefficient (damping coefficient) of the shock absorber 4b based on the physical quantity related to the motion of the vehicle 1 acquired by the acquisition unit 10a. The target damping coefficient can be calculated by a known method.

[0029] The timekeeping unit 10c is capable of measuring time. The timekeeping unit 10c includes a plurality of timers. In detail, the timekeeping unit 10c includes a vehicle stop determination timer 10da, an outside air temperature timer 10db, and a running determination timer 10dc.

[0030] The damping force control unit 10d controls the damping force of the shock absorber 4b based on the calculated target damping coefficient. Specifically, the damping force control unit 10d determines a current value to be input to the shock absorber 4b based on the calculated target damping coefficient, and inputs the current value to the shock absorber 4b.

[0031] Here, when the temperature of the hydraulic oil in the shock absorber 4b drops, the viscosity of the hydraulic oil increases, and abnormal noise may occur due to the movement of the hydraulic oil accompanying the operation of the shock absorber 4b. As a result of intensive research, the inventor of the present invention has found that, at an outside air temperature at which abnormal noise occurs in the shock absorber 4b, the generation of abnormal noise in the shock absorber 4b can be suppressed by increasing the damping force of the shock absorber 4b, i.e., by increasing the control current. From this point of view, in this embodiment, the following control is performed as the damping force control.

[0032] The damping force control unit 10d selectively executes normal control and low-temperature response control. The normal control is an example of a first damping force control, and the low-temperature response control is an example of a second damping force control. The normal control controls the damping force based on the physical quantity of the motion of the vehicle 1 when the temperature of the outside air is equal to or higher than the temperature threshold. That is, the normal control controls the damping force of the shock absorber 4b based on the calculated target damping coefficient. Here, in the normal control, a settable range of the damping force is determined in advance. The low-temperature response control sets the damping force higher than the lower limit value of the settable range, which is the range of the damping force that can be set in the normal control, when the temperature of the outside air is less than the temperature threshold. At this time, the low-temperature response control may set the range of the damping force in which the shock absorber 4b does not generate abnormal noise as the upper and lower limit values, and set the damping force within the settable range when the temperature of the outside air is less than the temperature threshold. The range of the damping force in which the shock absorber 4b does not generate abnormal noise is set in advance, for example, by experiments for each type of vehicle 1. In addition, the low temperature response control may set the damping force to a constant value higher than the lower limit value of the settable range regardless of the vehicle speed, which is the speed of the vehicle 1, or may change the damping force according to the vehicle speed. The outside air temperature is a temperature detected by a temperature sensor.

[0033] Furthermore, when the outside air temperature is below the temperature threshold, the damping force control unit 10d performs normal control if the time from when the vehicle 1 comes to a stop until it starts to move is equal to or shorter than a specified time. On the other hand, when the outside air temperature is below the temperature threshold, the damping force control unit 10d performs low temperature response control if the time from when the vehicle 1 comes to a stop until it starts to move exceeds a specified time. When performing low temperature response control, the damping force control unit 10d transitions to normal control if the vehicle 1 has been moving for a specified time or longer.

[0034] In addition, the damping force control unit 10d transitions from low temperature response control to normal control when the outside air temperature remains equal to or higher than the temperature threshold for a specified time after the low temperature response control is executed. In addition, when the outside air temperature falls below the temperature threshold while normal control is being executed, the damping force control unit 10d transitions to low temperature response control at the point when the outside air temperature falls below the temperature threshold.

[0035] Furthermore, the damping force control unit 10d executes normal control regardless of the outside air temperature when the speed of the vehicle 1 is equal to or greater than the speed threshold. The speed threshold is, for example, the speed at which the occupants cannot hear abnormal noises of the shock absorbers 4b due to the running sounds of the vehicle 1 (road noise, engine sound, etc.), and is set by experiment, etc. The low temperature response control can be executed when the speed of the vehicle 1 is less than the speed threshold.

[0036] That is, the damping force control section 10d transitions from the low-temperature response control to the normal control when one or more of the following conditions (1A) to (3A) are satisfied, for example. Condition (1A) is that vehicle 1 has been traveling for a certain period of time. Condition (2A) is that the outside air temperature has risen and a certain period of time has elapsed. The condition (3A) is that the vehicle speed reaches a vehicle speed (vehicle speed threshold) at which the abnormal noise of the shock absorber 4b is not audible.

[0037] Moreover, the damping force control section 10d shifts from the normal control to the low-temperature corresponding control when one of the following conditions (1B) to (3B) is satisfied, for example. Condition (1B) is that the outside air temperature is below the temperature threshold and the vehicle 1 is stopped for a certain period of time. Condition (2B) is when the outside air temperature drops and a certain period of time passes. Condition (3B) is that the outside air temperature is below the temperature threshold and the vehicle speed is below a vehicle speed (vehicle speed threshold) at which the abnormal noise of the shock absorber 4b is not audible, that is, the vehicle speed at which the abnormal noise of the shock absorber 4b is audible is reached.

[0038] Next, an example of the damping force control processing executed by the control device 10 will be described. Fig. 4 is a flowchart showing an example of the damping force control processing executed by the control device according to the embodiment. Fig. 5 is a flowchart showing an example of the stop / run determination processing in the damping force control processing according to the embodiment. Fig. 6 is a flowchart showing an example of the low temperature response control necessity determination processing in the damping force control processing according to the embodiment. Fig. 7 is a flowchart showing an example of the minimum outside air temperature update processing in the damping force control processing according to the embodiment. Fig. 8 is a flowchart showing an example of the control setting processing in the damping force control processing according to the embodiment.

[0039] The damping force control process shown in Fig. 4 is started, for example, when an ignition switch (not shown) is turned on, and is repeatedly executed while the ignition switch is in the on state. In the following description, the control of the damping force may be simply referred to as control.

[0040] The damping force control unit 10d executes a stop / run determination process (S11), a low temperature response control necessity determination process (S12), a minimum outside air temperature update process (S13), and a control setting process (S14). Each process will be described in detail below.

[0041] First, the stop / run determination process of S11 will be described with reference to the flowchart shown in FIG. 5. The damping force control unit 10d determines whether the vehicle 1 is stopped and the minimum outside temperature is less than the temperature threshold value of -20°C (S101: stop determination process). The reason for performing the stop determination in this manner is to enable low-temperature response control to be performed when the vehicle 1 has been stopped for a long time and the hydraulic oil of the shock absorber 4b has cooled down. Whether the vehicle 1 is stopped, that is, whether the vehicle 1 is running, is determined from the detection result of the rotation sensor 5. The minimum outside temperature is a temperature included in the control information stored in the storage unit 10e. The temperature threshold value is not limited to -20°C.

[0042] When the damping force control unit 10d determines that the vehicle 1 is stopped and the minimum outside temperature is less than -20 degrees (S101: Yes), it causes the timing unit 10c to start timing the vehicle stop determination timer 10da (S102) and proceeds to S103.

[0043] In S101, when the damping force control unit 10d determines that the vehicle 1 is stopped and the minimum outside temperature is not less than -20 degrees (S101: No), it causes the timing unit 10c to stop timing of the stop determination timer 10da (S106) and proceeds to S107. Note that, in S106, when the timing of the stop determination timer 10da is stopped, the damping force control unit 10d keeps it stopped.

[0044] In S107, the damping force control unit 10d judges whether the current vehicle speed exceeds 20 km / h (traveling judgment process). When the damping force control unit 10d judges that the current vehicle speed exceeds 20 km / h (S107: Yes), it causes the timing unit 10c to start timing the travelling judgment timer 10dc (S108). This process is for making it possible to judge whether the hydraulic oil has been warmed up by the vehicle 1 traveling. After that, the damping force control unit 10d proceeds to S103.

[0045] In S103, the damping force control unit 10d determines whether the current outside air temperature exceeds 20° C. The current outside air temperature is the temperature detected by the temperature sensor 14. When the damping force control unit 10d determines that the current outside air temperature exceeds 20° C. (S103: Yes), it causes the timing unit 10c to start timing the outside air temperature timer 10db (S104). This process is intended to make it possible to determine, for example, whether the outside air temperature has risen and the hydraulic oil has warmed up while the vehicle 1 is not running.

[0046] On the other hand, when the damping force control unit 10d determines that the current outside air temperature does not exceed 20° C. (S103: No), it causes the timing unit 10c to stop timing the outside air temperature timer 10db (S105). Note that, when timing of the outside air temperature timer 10db is stopped in S105, the damping force control unit 10d keeps it stopped.

[0047] Next, the process of determining whether or not low temperature response control is required in S12 will be described with reference to the flowchart shown in Fig. 6. The damping force control unit 10d determines whether the time measured by the travel determination timer 10dc exceeds the threshold value of 60 minutes or the time measured by the outside air temperature timer 10db exceeds the threshold value of 60 minutes (S201).

[0048] If the damping force control unit 10d determines that the time measured by the driving judgment timer 10dc exceeds the threshold value of 60 minutes or the time measured by the outside air temperature timer 10db exceeds the threshold value of 60 minutes (S201: Yes), the damping force control unit 10d proceeds to S202.

[0049] In S202, the damping force control unit 10d sets the low temperature response control necessity flag to "1" in the control information 121, rewrites the minimum outside temperature to 100°C which is a predetermined high temperature, and stops the vehicle stop determination timer 10da. The predetermined high temperature is not a temperature detected by the temperature sensor 14, but a previously set abnormally high temperature (a temperature that does not normally occur). After S202, the damping force control unit 10d ends the low temperature response control necessity determination process.

[0050] In S201, if the damping force control unit 10d determines that the time measured by the driving judgment timer 10dc does not exceed the threshold value of 60 minutes and that the time measured by the outside air temperature timer 10db does not exceed the threshold value of 60 minutes (S201: No), the damping force control unit 10d proceeds to S203.

[0051] In S203, the damping force control unit 10d determines whether the vehicle stop determination timer 10da has exceeded the threshold value of 10 minutes. When the damping force control unit 10d determines that the vehicle stop determination timer 10da has exceeded the threshold value of 10 minutes (S203: Yes), the damping force control unit 10d proceeds to S204.

[0052] In S204, the damping force control unit 10d sets the low-temperature response control necessity flag to "0" in the control information 121, and stops the traveling determination timer 10dc. After S202, the damping force control unit 10d ends the low-temperature response control necessity determination process.

[0053] In S203, when the damping force control unit 10d determines that the vehicle stop determination timer 10da has not exceeded the threshold value of 10 minutes (S203: No), the damping force control unit 10d ends the low-temperature response control necessity determination process.

[0054] Next, the minimum outside air temperature updating process of S13 will be described with reference to the flowchart shown in Fig. 7. The damping force control unit 10d determines whether or not the current outside air temperature is lower than the minimum outside air temperature stored in the storage unit 10e (S301).

[0055] If the current outside air temperature is lower than the minimum outside air temperature stored in the memory unit 10e (S301: Yes), the damping force control unit 10d rewrites the minimum outside air temperature in the memory unit 10e to the current outside air temperature and updates the minimum outside air temperature (S302).

[0056] On the other hand, if the current outside air temperature is not lower than the minimum outside air temperature stored in the memory unit 10e (S301: No), the damping force control unit 10d terminates the minimum outside air temperature update process without updating the minimum outside air temperature in the memory unit 10e.

[0057] Next, the control setting process of S14 will be described with reference to the flowchart shown in Fig. 8. The damping force control unit 10d judges whether the low-temperature response control necessity flag is "0" (i.e., low-temperature response control is necessary) and the minimum outside air temperature is less than the temperature threshold value of -20°C (S401). In this way, by using the minimum outside air temperature, it is possible to reduce the influence of frequent fluctuations in the outside air temperature compared to the case where the current outside air temperature is used sequentially.

[0058] When the damping force control unit 10d determines that the low-temperature response control necessity flag is "0" (that is, low-temperature response control is necessary) and the minimum outside air temperature is less than the temperature threshold value of -20°C (S401: Yes), the damping force control unit 10d proceeds to S402.

[0059] In S402, the damping force control unit 10d determines whether or not the current vehicle speed of the vehicle 1 is less than the vehicle speed threshold value of 150 km / h. When the damping force control unit 10d determines that the current vehicle speed of the vehicle 1 is less than the vehicle speed threshold value of 150 km / h (S402: Yes), it sets low-temperature response control as the damping force control and executes the low-temperature response control (S403).

[0060] On the other hand, when the damping force control unit 10d determines in S401 that the low-temperature response control necessity flag is "0" (i.e., low-temperature response control is necessary) and the minimum outside air temperature is not less than the temperature threshold value of -20°C (S401: No), and when the damping force control unit 10d determines in S402 that the current vehicle speed of the vehicle 1 is not less than the vehicle speed threshold value of 150km / h (S402: No), the damping force control unit 10d sets normal control as the damping force control and executes the normal control (S404). Here, for example, when the vehicle 1 is an electric vehicle, the running sound of the vehicle 1 is relatively small, so that when an abnormal sound of the shock absorber 4b occurs, the abnormal sound is easily transmitted to the inside of the vehicle. Therefore, it is better to execute the low-temperature response control even when the vehicle is traveling at a relatively high speed. For this reason, the threshold value is set to 150km / h as an example. Note that the threshold values ​​described above are not limited to the above.

[0061] As described above, the control device 10 of this embodiment performs low-temperature response control, which is control for increasing the damping force when the outside air temperature is low and the vehicle speed is low, in order to suppress abnormal noise from the shock absorber 4b. Furthermore, if the shock absorber 4b warms up due to an increase in the outside air temperature or the vehicle 1 being driven for a certain period of time while the low-temperature response control is being performed, the control device 10 transitions from low-temperature response control to normal control because no abnormal noise is generated from the shock absorber 4b.

[0062] Fig. 9 is a timing chart showing an example of the damping force control process according to the embodiment. As shown in Fig. 9, switching between normal control and low-temperature response control is performed by the processes in Figs.

[0063] 10 is a diagram showing an example of the relationship between the vehicle speed and the control current in the low temperature response control of the damping force control process according to the embodiment. As shown in FIG. 10, in the present embodiment, in the low temperature response control, the control current is constant regardless of the vehicle speed.

[0064] As described above, in this embodiment, the control device 10 (damping force control device) controls the damping force of the shock absorber 4b4b interposed between the wheel 3 of the vehicle 1 and the body 2 of the vehicle 1. The control device 10 includes an acquisition unit 10a and a damping force control unit 10d. The acquisition unit 10a acquires a physical quantity related to the motion of the vehicle 1 and an outside air temperature of the vehicle 1. When the outside air temperature is equal to or higher than a temperature threshold, the damping force control unit 10d executes normal control (first damping force control) that controls the damping force based on the physical quantity, and when the outside air temperature is lower than the temperature threshold, executes low-temperature response control (second damping force control) that sets the damping force higher than the lower limit value of the settable range, which is the range of the damping force that can be set in the normal control.

[0065] According to this configuration, when the temperature of the outside air is below the temperature threshold, the damping force control unit 10d executes low-temperature response control to set the damping force higher than the lower limit of the settable range, which is the range of the damping force that can be set by normal control, so that the generation of abnormal noise of the shock absorber 4b can be suppressed. In addition, at this time, whether to execute normal control or low-temperature response control is determined based on the temperature of the outside air of the vehicle 1 corresponding to the temperature of the shock absorber 4b, so that the generation of abnormal noise of the shock absorber can be further suppressed compared to the case where the generation of abnormal noise of the shock absorber 4b is suppressed without using the temperature of the outside air of the vehicle 1. In addition, for example, by using a temperature sensor 14 that detects the outside air temperature displayed on a display device in the vehicle cabin as the damping force control, an increase in the configuration and cost of the vehicle 1 can be suppressed.

[0066] In addition, when the outside air temperature is below the temperature threshold and the time from when the vehicle 1 comes to a stop until when it starts moving is less than a specified time, the damping force control unit 10d performs normal control, and when the outside air temperature is below the temperature threshold and the time from when the vehicle 1 comes to a stop until when it starts moving exceeds a specified time, the damping force control unit 10d performs low temperature response control.

[0067] According to this configuration, when the outside air temperature is below the temperature threshold and the time from when the vehicle 1 comes to a stop to when it starts moving exceeds a specified time, the damping force control unit 10d implements low temperature response control, thereby suppressing the generation of abnormal noise from the shock absorber 4b.

[0068] Furthermore, when the state in which the outside air temperature is equal to or higher than the temperature threshold value continues for a specified time after the low-temperature response control is executed, the damping force control section 10d transitions from the low-temperature response control to the normal control.

[0069] According to this configuration, frequent changes in control are suppressed compared to a case in which the control is switched from low-temperature response control to normal control when the outside air temperature becomes equal to or higher than the temperature threshold value.

[0070] Furthermore, when the speed of the vehicle 1 is equal to or greater than the speed threshold, the damping force control unit 10d executes normal control regardless of the outside air temperature.

[0071] According to this configuration, when the speed of the vehicle 1 is equal to or greater than the speed threshold, if the abnormal noise of the shock absorber 4b becomes difficult to hear due to the traveling noise of the vehicle 1 (road noise, engine noise, etc.), normal control is executed, thereby improving the ride comfort.

[0072] Next, a modified example will be described.

[0073] Fig. 11 is a diagram showing an example of the relationship between vehicle speed and control current in low temperature response control of the damping force control process according to the first modified example of the embodiment. As shown in Fig. 11, in this modified example, in low temperature response control, the control current increases stepwise according to the vehicle speed. Note that the settable range of the damping force in normal control may be predetermined according to the vehicle speed.

[0074] Fig. 12 is a diagram showing an example of the relationship between vehicle speed and control current in low temperature response control of the damping force control process according to the second modified example of the embodiment. As shown in Fig. 12, in this modified example, in low temperature response control, the control current increases in proportion to the vehicle speed. Note that the settable range of the damping force in normal control may be predetermined according to the vehicle speed.

[0075] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0076] 1. Vehicle 2. Body 3...wheels 4b…Shock absorber 10...Control device (damping force control device) 10a…Acquisition part 10b…Calculation part 10c…Clock part 10d…Damping force control section

Claims

1. A damping force control device that controls a damping force of a shock absorber interposed between a wheel of a vehicle and a body of the vehicle, an acquisition unit that acquires a physical quantity related to the motion of the vehicle and an outside air temperature of the vehicle; a damping force control unit that executes a first damping force control for controlling the damping force based on the physical quantity when the temperature of the outside air is equal to or higher than a temperature threshold, and executes a second damping force control for setting the damping force higher than a lower limit value of the range that can be set by the first damping force control when the temperature of the outside air is lower than the temperature threshold; A damping force control device comprising:

2. The damping force control unit performs the first damping force control when the outside air temperature is less than the temperature threshold and the time from when the vehicle stops to when it starts to move is equal to or less than a specified time, and performs the second damping force control when the outside air temperature is less than the temperature threshold and the time from when the vehicle stops to when it starts to move exceeds the specified time. The damping force control device according to claim 1 .

3. the damping force control unit transitions from the second damping force control to the first damping force control when a state in which the outside air temperature is equal to or higher than the temperature threshold value continues for a specified time after the second damping force control is executed. The damping force control device according to claim 1 .

4. The damping force control unit executes the first damping force control regardless of the outside air temperature when the speed of the vehicle is equal to or higher than a speed threshold value. The damping force control device according to claim 1 .

5. The second damping force control sets the damping force to a constant value higher than a lower limit value of the range regardless of a vehicle speed, which is a speed of the vehicle, or changes the damping force according to the vehicle speed. The damping force control device according to claim 1 .

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