JP2007255434A - Control device for shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for a shock absorber not deteriorating riding quality of a vehicle even if temperature of liquid in the shock absorber changes. <P>SOLUTION: The control device for the shock absorber executes PWM control of a solenoid S and controls generating damping force based on deviation of current flowing in a coil of the solenoid S in a solenoid valve SV changing valve opening according to thrust of the solenoid built in the shock absorber D from target current value. A liquid temperature estimation means estimating liquid temperature in the shock absorber D based on current flowing the coil of the solenoid S or target current value and duty ratio. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a shock absorber control device incorporating a solenoid valve for adjusting damping force.

  In general, in a control device that controls a solenoid, for example, current detection means for detecting a current flowing in the solenoid coil, and control for PWM control of the solenoid by feeding back a current value detected by the current detection means The control means includes an arithmetic unit that calculates a target current value to be supplied to the coil and generates a current command, a pulse generation circuit that generates a PWM signal based on the current command, and a PWM A device having a switching element for supplying a current to the coil at a duty ratio based on a signal is known.

  In the solenoid control device as described above, the current value actually flowing through the solenoid coil is fed back to obtain a deviation between the target current value and the actual current value, and proportional integral control is performed based on this deviation. Etc. are generally performed.

In such a control device, the current value flowing through the solenoid can be accurately matched with the target current value, thereby controlling the valve opening of the solenoid valve and providing a desired damping force to the buffer. This is very useful because it can be generated, and the duty ratio in the PWM signal can be corrected by feeding back the value of the current that actually flows through the solenoid coil and taking the deviation from the target current value. Even if the coil coil temperature changes due to the heat generation of the solenoid coil itself or the usage environment, the coil current value can match the target current value, and the solenoid thrust force Can be controlled as intended (see Patent Document 1).
JP-A-8-240277 (conventional technology column)

  However, when the solenoid control device described above is applied to a solenoid valve of a shock absorber, there are the following problems.

  The shock absorber basically includes a cylinder, a piston slidably inserted into the cylinder, and a piston rod connected to the piston, and hydraulic oil or the like is provided in two chambers partitioned by the piston in the cylinder. When the piston moves with respect to the cylinder, the hydraulic oil in the two chambers is made to exchange with the flow path provided in the piston, etc., and the valve passes through the flow path and resists the liquid passing through the flow path. A damping force is generated by giving a pressure difference to each room.

  And the magnitude of the resistance that the valve gives to the liquid depends on the viscosity of the liquid, but the viscosity of the liquid changes depending on the temperature rise due to repeated expansion and contraction of the buffer and the environment in which the buffer is used, Even if the valve opening is constant, the magnitude of the resistance given to the liquid changes due to the change in the viscosity of the liquid.

  Then, when trying to control a solenoid valve that changes the valve opening according to the thrust of the solenoid with a conventional control device, even if the current feedback control can cope with the temperature change of the coil itself, Changes in liquid viscosity due to changes in liquid temperature cannot be handled, especially when the temperature of the liquid increases, the resistance that the valve gives to the liquid decreases, and the damping force generated by the shock absorber decreases. It will be a situation.

  When the shock absorber is applied to a vehicle, the temperature of the liquid in the shock absorber generally increases with the lapse of the vehicle travel time, so the conventional control device lacks the damping force generated by the shock absorber. As a result, it becomes impossible to perform the vehicle attitude control as intended, and the riding comfort of the vehicle is deteriorated.

  Accordingly, the present invention provides a control device for a shock absorber that has been devised to improve the above-described problems and does not impair the riding comfort of the vehicle even if the temperature of the shock absorber liquid changes. That is.

  In order to achieve the above-described object, the shock absorber control device of the present invention includes a current flowing through a solenoid coil and a target current value in a solenoid valve that changes a valve opening according to a thrust of a solenoid built in the shock absorber. The solenoid is subjected to PWM control based on the deviation from the above to control the generated damping force, and the liquid temperature in the buffer is estimated based on the current flowing through the solenoid coil or the target current value and the duty ratio. The liquid temperature estimation means is provided.

  According to the present invention, since it is possible to estimate the temperature change of the liquid, it becomes possible to appropriately control the valve opening with respect to the temperature of the liquid, regardless of the temperature change of the liquid in the buffer, It is possible to generate a damping force as aimed at the shock absorber.

  Therefore, it becomes possible to generate the damping force as aimed at the shock absorber regardless of the temperature change of the liquid in the shock absorber, so that the vehicle posture and the vehicle body vibration can be appropriately controlled, and the vehicle The riding comfort can be improved. In particular, the vehicle is excellent in riding comfort when starting in a cold region or when the liquid in the shock absorber is at a low temperature or a high temperature.

  In addition, since it is possible to estimate the liquid temperature without providing a sensor for detecting the temperature of the liquid in the buffer, it is possible to estimate the liquid temperature at a low cost.

  Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a conceptual diagram of a shock absorber control device and a shock absorber to which the control device is applied according to an embodiment. FIG. 2 is a system diagram of a shock absorber control device according to an embodiment. FIG. 3 is a map showing the relationship between the damping force and the target current value. FIG. 4 is a flowchart illustrating an example of a procedure of liquid temperature estimation and target current value correction in the shock absorber control device according to the embodiment. FIG. 5 is a diagram showing the relationship between the coil resistance of the solenoid and the duty ratio. FIG. 6 is a map showing the relationship between the coil temperature and the duty ratio with respect to the current value.

  As shown in FIG. 1, the control device for the shock absorber in one embodiment performs PWM control of the solenoid S of the solenoid valve SV built in the shock absorber D, and the current flowing in a coil (not shown) of the solenoid S. A current detector 1 for detecting the current, a control unit 2 for generating a PWM signal for PWM control of the solenoid S, a power supply 3 for supplying power to the coil of the solenoid S, and a solenoid with a duty ratio corresponding to the generated PWM signal And a switching element 4 for applying a voltage to the S coil.

  On the other hand, the shock absorber D is interposed between a vehicle body and an axle (not shown) and exhibits a damping action for damping the vibration of the vehicle body, and is slidably inserted into the cylinder C and the cylinder C. A piston P, a rod R that is movably inserted into the cylinder C and one end of which is connected to the piston P, an upper chamber A and a lower chamber B partitioned by the piston P in the cylinder C, and a piston P Of the upper chamber A and the lower chamber B, and a solenoid valve SV provided in the piston P. In the upper chamber A and the lower chamber B, liquid, In the embodiment, the hydraulic oil is filled, and the solenoid valve SV described above includes a valve portion V provided in the middle of the flow path L and a solenoid S for adjusting the opening degree of the valve portion V.

  In addition, when the shock absorber D expands and contracts, the hydraulic oil corresponding to the volume of the rod R entering or leaving the cylinder C becomes excessive or insufficient in the cylinder C. This is compensated by a change in volume of the gas chamber or a reservoir (not shown). Further, the shock absorber D may be a so-called single cylinder type or a double cylinder type. In the illustrated case, the shock absorber D is a single rod type but may be a double rod type.

  And it is possible to give resistance to the flow of the hydraulic oil at the valve portion V against the alternating current of the hydraulic oil through the flow path L between the upper chamber A and the lower chamber B when the shock absorber D expands and contracts. Further, the opening of the valve portion V can be adjusted according to the thrust of the solenoid S, and the magnitude of the resistance can be adjusted by adjusting the opening. .

  Further, in the above place, the damping force is not generated only by the solenoid valve SV, but another passage is provided in parallel with the flow path L to connect the upper chamber A and the lower chamber B, and the passage is attenuated. A force generation element may be provided, and the generated damping force may be set to the soft side by the solenoid valve SV.

  Since the solenoid S is well known, it will not be described in detail, but a stator constituted by a coil and a fixed iron core excited by energization of the coil, a movable iron core provided in the coil, and a movable iron core are provided. A spring urging away from the fixed iron core, and adjusting the attractive force by exciting the fixed iron core and changing the thrust applied to the movable iron core by the urging force of the spring. To adjust the opening of the valve portion V.

  Therefore, the solenoid valve SV can adopt various configurations as long as the opening degree of the valve portion V can be changed by the thrust applied by the solenoid S to the valve portion V. For example, the solenoid S In addition to the change of the opening degree of the valve portion V only by the thrust of the hydraulic fluid, the hydraulic oil pressure is also applied to the valve portion V, and the thrust of the solenoid S acting on the valve portion V and the pressure of the hydraulic oil are Of course, the opening degree of the valve portion V may be adjusted according to the balance.

  Further, as described above, the solenoid valve SV is built in the shock absorber D, and the coil of the solenoid S is sealed and accommodated in the cylinder C. In this specification, the solenoid S being built in the shock absorber D means that the coil of the solenoid S is at least housed in the shock absorber D, and the shock absorber D passes through the reservoir and the passage. When an outer cylinder is provided outside the cylinder C to form the outer cylinder, the outer cylinder is also included in the shock absorber D.

  Subsequently, one end of a coil (not shown) of the solenoid S described above is connected to a power source 3 installed outside the shock absorber D by a line 5, and a switching element 4 is provided in the middle of the line 5. The switching element 4 energizes the coil of the solenoid S by opening and closing with a duty ratio corresponding to a PWM signal from the control unit 2 described later. Specifically, the switching element 4 is, for example, a transistor such as a MOSFET (MOS: Metal Oxide Semiconductor, FET: Field Effect Transistor).

  Further, the other end of the coil (not shown) of the solenoid S is grounded by a line 6, and a current detector 1 is provided in the middle of the line 6, and the current detected by the current detector 1 is detected. Is input to the control unit 2 as a current signal composed of a voltage.

  Subsequently, as shown in FIG. 2, the control unit 2 includes a CPU (Central Processing Unit) 21, a ROM (Read Only Memory) 22, a RAM (Random Access Memory) 23, and a PWM circuit 24. The analog signal of the current detector 1 is converted into a digital signal via the A / D converter 25 and taken in, and a PWM signal can be output to the switching element 4. The current value actually flowing through the solenoid S detected by the current detector 1 is taken into the control unit 2 at a predetermined sampling period and stored in the RAM 23.

  In addition, the control unit 2 performs skyhook from signals output from sensors that detect state quantities necessary for controlling the posture of the vehicle such as a vehicle speed detector, a steering angle detector, and a vehicle body acceleration detector mounted on a vehicle (not shown). In accordance with a predetermined vehicle body posture control law such as a control law, a damping force command value that is the magnitude of the damping force from the posture control device E that calculates the damping force to be generated by the shock absorber D is fetched. The CPU 21 calculates a target current value to be supplied to the coil of the solenoid S from the damping force command value, and stores the target current value in the RAM 23. Note that the above-described damping force command value may be a damping coefficient value that realizes the damping force to be generated by the shock absorber D, not as a damping force value.

  When calculating the target current value, as shown in FIG. 3, the relationship between the applied damping force command value and the current value supplied to the coil of the solenoid S is previously mapped, and this map is stored in the RAM 23. The CPU 21 reads the map and calculates the target current value to be supplied to the coil of the solenoid S from the damping force command value by map calculation. The target current value described above corresponds to the opening degree of the valve unit V. When the current of the target current value is supplied to the coil of the solenoid S, the buffer unit D attenuates the opening degree of the valve unit V. Adjustment is made to generate a damping force according to the force command value. Further, the solenoid valve SV is set so that the damping force increases as the amount of current supplied to the coil of the solenoid S increases, that is, the opening degree of the valve portion V decreases, as shown in FIG. The target current value decreases as the damping force command value increases. When the given damping force command value is a damping coefficient, if the relationship between the damping coefficient and the target current value is mapped, the opening of the valve portion V is adjusted and buffered in the same manner as described above. The damping force according to the damping force command value can be generated in the device D.

  The CPU 21 basically reads the current value detected by the current detector 1 stored in the RAM 23 and the target current value, calculates their deviation, and based on this deviation, a well-known proportional integration A voltage command value to be applied to the coil of the solenoid S is calculated according to a control law or a proportional-integral-derivative control law, a duty ratio for applying the solenoid S is determined from the voltage command value, and the switching element is connected via the PWM circuit 24. 4 outputs a PWM signal.

  Therefore, in this control device, the solenoid S can be PWM controlled to adjust the opening degree of the valve portion V, and the generated damping force of the shock absorber D can be controlled as commanded by the attitude control device E. In addition, the control unit 2 estimates the liquid temperature in the buffer D based on the current flowing through the coil of the solenoid S and the duty ratio according to the procedure shown in FIG. 4, and corrects the target current value based on the liquid temperature. Can be done.

  The procedure shown in FIG. 4 is stored in advance in the ROM 22 or the RAM 23 as a program that can be executed by the CPU 21, and the CPU 21 is a correction means for correcting the target current value based on the liquid temperature estimation means and the estimated liquid temperature. This is realized by executing the above program.

  In order to estimate the temperature of the hydraulic fluid that is a liquid in the present embodiment, specifically, the coil temperature of the solenoid S is calculated from the current flowing through the solenoid S or the target current value and the duty ratio, and this coil temperature is calculated. By referring to a map prepared in advance as a parameter, a map calculation for estimating the hydraulic oil temperature is performed to determine the hydraulic oil temperature.

  First, in step F1, the CPU 21 reads the duty ratio when the solenoid S is subjected to PWM control by opening and closing the switching element 4 by the PWM signal output from the PWM circuit 24 in performing the proportional integral control of the solenoid S. This duty ratio is calculated by the CPU 21 and stored in the RAM 23 in the control routine for the PWM control.

  Subsequently, in step F2, the influence of the voltage change of the power source 3 is excluded from the read duty ratio, and in step F3, the coil temperature of the solenoid S is estimated from the duty ratio excluding the influence of the voltage change. The correction of the voltage influence in step F2 will be described later.

  The estimation of the coil temperature in step F3 will be described in detail. The internal resistance value of the coil of the solenoid S changes due to a temperature change, and the change of the resistance value of this coil can be estimated from the relationship between the current flowing through the coil of the solenoid S or the duty ratio with respect to the target current value. is there. That is, as shown in FIG. 5, when a current of 1A is passed through the solenoid S, for example, if the coil temperature is high, the coil resistance increases as shown in FIG. The duty ratio is larger than the on-duty ratio in FIG. 5B when the coil temperature is low. That is, when the current is constant, the coil temperature and the coil resistance of the solenoid S are in a proportional relationship, and the duty ratio is also proportional to the coil temperature and the coil resistance. It is possible to estimate the coil temperature from the current actually flowing through the coil or the target current value and the duty ratio. In this estimation of the coil temperature, as shown in FIG. 6, the relationship between the coil temperature and the duty ratio with respect to a plurality of current values is mapped and the map temperature is calculated to estimate the coil temperature. Since the current value and the duty ratio are proportional to each other when the current is constant, the relationship between the coil temperature and the duty ratio for this current value is mapped using the current value as a reference current, and the coil for this current value is mapped. The coil temperature may be estimated from a map showing the relationship between the temperature and the duty ratio and the current actually flowing through the coil of the solenoid S or the ratio between the target current value and the reference current, or the duty ratio and the power supply voltage are multiplied. Thus, the average applied voltage of the coil of the solenoid S can be calculated. Since the coil resistance proportional to the coil temperature can be calculated by dividing the current actually flowing through the current or the target current value, the coil temperature can be estimated without using the above-described maps. Good.

  Then, the process proceeds to step F4, and the hydraulic oil temperature is estimated after determining the coil temperature. Since the coil of the solenoid S is built in the shock absorber D in a sealed state, the coil of the solenoid S There will be hydraulic oil around, and the coil temperature of the solenoid S will correlate with the ambient hydraulic oil temperature.

  Therefore, by estimating the coil temperature, it is possible to estimate the hydraulic oil temperature that correlates with the coil temperature. In practice, the correlation between the experimentally obtained coil temperature and hydraulic oil temperature is mapped in advance. The map is stored in the ROM 22 of the control unit 2 as a map for calculating the hydraulic oil temperature using the coil temperature as a parameter.

  That is, when estimating the hydraulic oil temperature, the CPU 21 of the control unit 2 first calculates the coil temperature from the current flowing through the solenoid S or the target current value and the duty ratio in step F3, and the obtained coil. The hydraulic oil temperature is calculated from the temperature by map calculation in step F4.

  Furthermore, in the control device for the shock absorber in the present embodiment, when estimating the hydraulic oil temperature in the above procedure, the influence corresponding to the voltage change of the power supply 3 is excluded in order to eliminate the influence due to the voltage change of the power supply 3. Correct coil temperature by minutes. When a constant current is supplied to the coil of the solenoid S, the voltage change of the power supply 3 appears in proportion to the change of the duty ratio. Therefore, the above-described procedure is performed after the duty ratio is corrected by the influence of the voltage change. The hydraulic oil temperature may be estimated at

  Specifically, as shown in FIG. 2, a voltage detector 7 for detecting the voltage of the power source 3 is provided, and a voltage signal which is an analog signal indicating a voltage value detected by the voltage detector 7 is converted to A / D. The signal is converted into a digital signal via the converter 26 and captured by the control unit 2, and the duty ratio read in step F1 is corrected in step F2.

  And a map used to correct the coil temperature described above, that is, a map group showing the relationship between the coil temperature and the duty ratio for a plurality of current values, or a coil for this current value with a certain current value as a reference current The map showing the relationship between temperature and duty ratio is created in advance with reference to the voltage expected to be output from the power source 3, and is detected by the voltage detector 7 based on the actual duty ratio read in step F1. The actual duty ratio is corrected by multiplying the actual power supply 3 voltage by the ratio obtained by dividing the voltage of the actual power supply 3 by the reference voltage to convert the duty ratio when the power supply 3 is outputting the reference voltage.

  Therefore, the corrected duty ratio becomes the duty ratio when the power source 3 outputs the reference voltage as described above. Therefore, the coil temperature and the duty ratio at the reference voltage are calculated from the corrected duty ratio. If the calculation is performed using a map indicating the relationship, the coil temperature can be estimated while eliminating the influence of the voltage change of the power supply 3.

  When the relationship between the coil temperature and the duty ratio is mapped and the coil temperature is not subjected to a map calculation, a voltage detector is used when calculating the average applied voltage of the solenoid S by multiplying the duty ratio and the power supply voltage. What is necessary is just to calculate an average applied voltage by multiplying the voltage of the actual power supply 3 detected in 7 by the duty ratio.

  Subsequently, since the operating oil temperature can be estimated with high accuracy by the procedure described above, the viscosity of the operating oil can be grasped at the operating oil temperature. And it transfers to step F5 and calculates the target electric current value which implement | achieves the opening degree of the valve part V which satisfies the damping force command value of the attitude | position control apparatus E. Specifically, in this step F5, for example, a reference target current value is calculated from a map of the damping force command value and the target current value, and the reference target current value is multiplied by a gain corresponding to the viscosity change. Thus, the target current value is corrected.

  In this case, the hydraulic oil temperature when the target current value serving as a reference is calculated as a reference temperature is set as a reference temperature, and the target current value serving as a reference is set in advance according to the difference between the hydraulic oil temperature estimated with respect to the reference temperature Set the gain to be multiplied.

  In this embodiment, the gain is set so that the opening degree of the valve portion V increases as the amount of current supplied to the coil of the solenoid S increases, assuming that the estimated operating oil temperature is the reference temperature. In this case, the hydraulic oil temperature is set to be lower than 1 if the hydraulic oil temperature is higher than the reference temperature, and is set to be higher than 1 if the hydraulic oil temperature is lower than the reference temperature, and the difference between the hydraulic oil temperature and the reference temperature can be increased. The greater the difference is from 1, which is the gain at the reference temperature.

  Further, when the operation reverse to that of the solenoid valve SV of the present embodiment is performed, that is, when the opening degree of the valve portion V becomes smaller as the amount of current supplied to the coil of the solenoid S becomes larger, this gain becomes It may be set to be greater than 1 if the hydraulic oil temperature is higher than the reference temperature, and smaller than 1 if the hydraulic oil temperature is lower than the reference temperature, and if the difference between the hydraulic oil temperature and the reference temperature is increased. It is set so that the deviation from 1, which is the gain at the reference temperature, increases.

  The gain may be set in consideration of a change in the characteristic of the valve part V (attenuation characteristic with respect to the opening degree of the valve part V) due to a change in the viscosity of the hydraulic oil, and may be obtained experimentally. Needless to say.

  Thus, in the control device of the present embodiment, the liquid temperature in the buffer D is estimated based on the current flowing through the coil of the solenoid S and the duty ratio, and the target current value is corrected based on the liquid temperature. This series of steps is repeatedly executed during the control of the shock absorber D, and continuously allows the shock absorber D to generate a damping force as commanded by the attitude control device E.

  In addition to this, in the control device of the present embodiment, after calculating the coil temperature in step F3 described above, the process proceeds to step F6 to determine whether the coil temperature is abnormally high. . The determination in step F6 is performed, for example, by determining whether or not a preset temperature threshold value is exceeded. When the hydraulic oil temperature exceeds the temperature threshold value, the hydraulic oil becomes very hot and is buffered. Since there is a possibility that the damping force required for the device D cannot be exhibited or there is a possibility that the control system is abnormal, it is not appropriate to continue the control any more. Stop proportional integral control.

  In this case, like the solenoid valve SV of the present embodiment, the opening degree of the valve portion V may be set to be increased according to the amount of current applied to the coil of the solenoid S. By doing so, By stopping energization of the coil of the solenoid S, it is possible to cause the shock absorber D to always generate a damping force with the maximum damping coefficient, and it is possible to surely shift to the fail-safe mode.

  The determination in step F6 may be set so that proportional integral control of the solenoid S is stopped when the coil temperature continuously exceeds the temperature threshold at different control time points. May be set so that the proportional integral control of the solenoid S is resumed when the temperature falls below the temperature threshold.

  As described above, in the control device for the shock absorber D, the temperature of the hydraulic fluid that is the liquid in the shock absorber D is estimated based on the current flowing through the coil of the solenoid S or the target current value and the duty ratio. Therefore, it is possible to estimate the temperature of the hydraulic oil at a low cost without specially providing sensors for detecting the temperature of the hydraulic oil in the shock absorber D, and based on the current flowing through the solenoid and the duty ratio. Since the solenoid coil temperature is calculated and the hydraulic oil temperature is estimated from the obtained coil temperature, the hydraulic oil temperature can be estimated easily and with high accuracy.

  Furthermore, since the opening degree of the valve portion V can be appropriately controlled with respect to the temperature change of the hydraulic oil, the damping as aimed at the shock absorber D regardless of the temperature change of the hydraulic oil of the shock absorber D. It is possible to generate force.

  Therefore, according to the control device for the shock absorber D, it is possible to generate the damping force as aimed at the shock absorber D regardless of the temperature change of the hydraulic oil in the shock absorber D. It is possible to appropriately control the vibration and improve the riding comfort in the vehicle. In particular, when starting in a cold region or when the hydraulic fluid of the shock absorber D is at a low temperature or a high temperature, the vehicle ride comfort is improved.

  In addition, since the temperature of the hydraulic fluid, which is a liquid, can be estimated with high accuracy even when the voltage of the power source that supplies power to the coil of the solenoid S is increased, the riding comfort of the vehicle is deteriorated even when the voltage changes. There is no harmful effect.

  Further, when the coil temperature or the temperature of the hydraulic fluid that is liquid is abnormal, the solenoid S is stopped to shift to the fail-safe mode, so that even if there is an abnormality, the minimum multiplication factor is obtained. It is possible to ensure comfort.

  In the above description, the present invention has been described as an example in which the solenoid valve SV is provided in the piston P of the shock absorber D. However, if the solenoid valve SV is incorporated in the shock absorber D, It goes without saying that the solenoid valve SV may be applied to the base valve portion that causes a pressure difference between the reservoir of the shock absorber D and the lower chamber B.

  In the present embodiment, the control device for the shock absorber D and the posture control device E for controlling the posture of the vehicle are described separately. However, the control device for the shock absorber D also serves as the posture control device. It may be configured as such.

  This is the end of the description of the embodiment of the present invention, but the scope of the present invention is of course not limited to the details shown or described.

1 is a conceptual diagram of a shock absorber control device according to an embodiment and a shock absorber to which the control device is applied. It is a system diagram of a control device of a shock absorber in one embodiment. It is a map which shows the relationship between damping force and a target electric current value. It is a flowchart which shows an example of the procedure of the estimation of the liquid temperature in the control apparatus of the buffer in one Embodiment, and correction | amendment of a target electric current value. It is a figure which shows the relationship between the coil resistance of a solenoid, and a duty ratio. It is a map which shows the relationship between the coil temperature with respect to an electric current value, and a duty ratio.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Current detector 2 Control part 21 CPU
22 ROM
23 RAM
24 PWM circuit 25, 26 A / D converter 3 Power supply 4 Switching element 5, 6 Line 7 Voltage detector A Upper chamber B Lower chamber C Cylinder D Buffer L Flow path P Piston R Rod SV Solenoid valve S Solenoid V Valve section

Claims (5)

A buffer for controlling the generated damping force by PWM control of the solenoid based on the deviation between the target current value and the current flowing in the solenoid coil in the solenoid valve that changes the valve opening according to the thrust of the solenoid built in the shock absorber. A shock absorber comprising a liquid temperature estimating means for estimating a liquid temperature in the shock absorber based on a current flowing through the solenoid coil or a target current value and a duty ratio. Control device. 2. The shock absorber control device according to claim 1, further comprising correction means for correcting the target current value based on the estimated liquid temperature. The liquid temperature estimating means calculates the solenoid coil temperature based on the current flowing through the solenoid coil and the duty ratio, and estimates the liquid temperature from the obtained coil temperature. Buffer control device. 4. The shock absorber control device according to claim 3, wherein the liquid temperature estimating means estimates the liquid temperature by referring to a map created in advance using the coil temperature of the solenoid as a parameter. 5. The shock absorber control device according to claim 1, wherein the liquid temperature estimating means corrects the liquid temperature estimated based on a power supply voltage value for supplying power to a coil of the solenoid.

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