Lifetime determination device and lifetime determination method

Abstract

To provide a service life determination device that can determine the service life of a pressure accumulating tank.SOLUTION: An ECU 4 is configured to determine the service life of a pressure accumulating tank. The pressure accumulating tank has a gas chamber filled with gas, an oil chamber connected to a common passage, and a piston that partitions between the gas chamber and the oil chamber. The pressure accumulating tank is configured to store hydraulic oil in the oil chamber and to discharge the hydraulic oil from the oil chamber. An ECU 4 calculates a movement amount of the piston on the basis of the volumetric change in the gas chamber. The ECU 4 determines that the service life of the pressure accumulating tank has expired when the integrated value of the calculated movement amount exceeds a threshold.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a life determination device and a life determination method.

Background Art

[0002] Conventionally, an accumulator tank provided in a common passage of a vehicle height adjustment system has been known (see, for example, Patent Document 1).

[0003] The accumulator tank has a gas chamber filled with gas, an oil chamber connected to the common passage, and a piston that partitions the gas chamber and the oil chamber. The accumulator tank stores hydraulic oil in the oil chamber and is configured to be able to discharge the hydraulic oil in the oil chamber.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Here, in order to appropriately use up the accumulator tank, it is desired to be able to determine the life of the accumulator tank.

[0006] The present invention has been made to solve the above problems, and an object of the present invention is to provide a life determination device and a life determination method capable of determining the life of an accumulator tank.

Means for Solving the Problems

[0007] The life determination device according to the present invention determines the life of an accumulator tank. The accumulator tank has a gas chamber filled with gas, an oil chamber connected to an oil passage, and a piston that partitions the gas chamber and the oil chamber. The accumulator tank stores hydraulic oil in the oil chamber and is configured to be able to discharge the hydraulic oil in the oil chamber. The life determination device includes a movement amount calculation unit and a life determination unit. The movement amount calculation unit calculates the movement amount of the piston based on the volume change of the gas chamber. The life determination unit determines that the life of the accumulator tank has arrived when the integrated value of the movement amount calculated by the movement amount calculation unit exceeds a threshold value.

[0008] By configuring in this way, the life of the accumulator tank can be determined based on the movement amount of the piston.

[0009] In the above life determination device, a volume change calculation unit that calculates the volume change of the gas chamber may be provided. The volume change calculation unit may be configured to calculate the volume change of the gas chamber based on the temperature of the gas chamber before pressure accumulation, the pressure of the gas chamber before pressure accumulation, the temperature of the gas chamber after pressure accumulation, and the pressure of the gas chamber after pressure accumulation.

[0010] In this case, the oil passage is a common passage of a vehicle height adjustment system, and a temperature sensor that detects the temperature of the hydraulic oil and a pressure sensor that detects the pressure of the hydraulic oil may be provided in the common passage. The temperature of the gas chamber may be estimated based on the detection result of the temperature sensor, and the pressure of the gas chamber may be estimated based on the detection result of the pressure sensor.

[0011] The life determination method according to the present invention determines the life of an accumulator tank. The accumulator tank has a gas chamber filled with gas, an oil chamber connected to an oil passage, and a piston that partitions the gas chamber and the oil chamber. The accumulator tank stores hydraulic oil in the oil chamber and is configured to be able to discharge the hydraulic oil in the oil chamber. The life determination method includes a step of calculating the movement amount of the piston based on the volume change of the gas chamber, and a step of determining that the life of the accumulator tank has arrived when the integrated value of the calculated movement amount exceeds a threshold value.

Advantages of the Invention

[0012] According to the life determination device and the life determination method of the present invention, the life of the accumulator tank can be determined.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0014] Hereinafter, an embodiment of the present invention will be described.

[0015] First, the configuration of the vehicle height adjustment system 100 to which the ECU 4 according to an embodiment of the present invention is applied will be described.

[0016] The vehicle height adjustment system 100 is configured to adjust the height position of the vehicle body (not shown) with respect to the wheels in the vehicle. As shown in FIG. 1, the wheels include a left front wheel 50FL, a right front wheel 50FR, a left rear wheel 50RL, and a right rear wheel 50RR. The front wheel 50FL is rotatably held by the front wheel holding member 51FL, the front wheel 50FR is rotatably held by the front wheel holding member 51FR, the rear wheel 50RL is rotatably held by the rear wheel holding member 51RL, and the rear wheel 50RR is rotatably held by the rear wheel holding member 51RR.

[0017] The vehicle height adjustment system 100 includes four hydraulic cylinders 1, a hydraulic fluid supply and discharge device 2, a hydraulic circuit 3, and an ECU 4 (see FIG. 4). The four hydraulic cylinders 1 include hydraulic cylinders 1FL, 1FR, 1RL, and 1RR. Note that the ECU 4 is an example of the "lifetime determination device" of the present invention.

[0018] The hydraulic cylinder 1FL is provided between the front wheel holding member 51FL and the vehicle body. The hydraulic cylinder 1FL functions as a shock absorber. The hydraulic cylinder 1FL is configured to be able to adjust the distance between the front wheel holding member 51FL and the vehicle body by expanding and contracting. Note that a suspension spring (not shown) is provided in parallel with the hydraulic cylinder 1FL between the front wheel holding member 51FL and the vehicle body.

[0019] Specifically, the hydraulic cylinder 1FL includes a housing 11, a piston 12, and a piston rod 13. The housing 11 has an internal space, the piston 12 is movably accommodated in the internal space, and the piston rod 13 is connected to the piston 12. The housing 11 is connected to the front wheel holding member 51FL, and the piston rod 13 is connected to the vehicle body. The internal space of the housing 11 is partitioned by the piston 12, and oil chambers 14 and 15 are formed. A communication passage 16 is formed in the piston 12, and the oil chambers 14 and 15 are communicated by the communication passage 16. A throttle is provided in the communication passage 16. For this reason, the hydraulic cylinder 1FL is configured to generate a damping force according to the moving speed of the piston 12 with respect to the housing 11.

[0020] The hydraulic cylinder 1FR is provided between the front wheel holding member 51FR and the vehicle body. The hydraulic cylinder 1RL is provided between the rear wheel holding member 51RL and the vehicle body. The hydraulic cylinder 1RR is provided between the rear wheel holding member 51RR and the vehicle body. The other configurations of the hydraulic cylinders 1FR, 1RL, and 1RR are the same as those of the above-described hydraulic cylinder 1FL.

[0021] The hydraulic fluid supply and discharge device 2 is provided to supply and discharge hydraulic fluid to and from four hydraulic cylinders 1 via a hydraulic circuit 3. The hydraulic fluid supply and discharge device 2 includes an oil pump 21, a brush motor 22, a reservoir tank 23, a check valve 24, and a return valve 25.

[0022] The reservoir tank 23 stores hydraulic fluid. The oil pump 21 is provided to pump up the hydraulic fluid in the reservoir tank 23 and supply it to a common passage 31 (described later) of the hydraulic circuit 3. The brush motor 22 is a power source for the oil pump 21 and is provided to operate the oil pump 21. The brush motor 22 is a motor that operates by a mechanical mechanism using brushes and a commutator. The check valve 24 and the return valve 25 are arranged in parallel on the discharge port side of the oil pump 21.

[0023] The check valve 24 is configured to allow the flow of hydraulic fluid from the oil pump 21 toward the common passage 31 and block the flow of hydraulic fluid from the common passage 31 toward the oil pump 21. The return valve 25 is provided to switch between the supply of hydraulic fluid from the oil pump 21 to the common passage 31 and the discharge of hydraulic fluid from the common passage 31 to the reservoir tank 23. Specifically, when the oil pump 21 is stopped, the return valve 25 blocks the discharge port side of the oil pump 21 from communicating with the common passage 31 and connects the common passage 31 to the reservoir tank 23 side. On the other hand, when the oil pump 21 is operating, the return valve 25 blocks the reservoir tank 23 side from communicating with the common passage 31 and connects the common passage 31 to the discharge port side of the oil pump 21.

[0024] The hydraulic circuit 3 is provided between the four hydraulic cylinders 1 and the hydraulic fluid supply and discharge device 2. The hydraulic circuit 3 includes a common passage 31, four individual passages 32, four vehicle height adjustment valves 33, an accumulator tank 34, and a tank control valve 35. The four individual passages 32 include individual passages 32FL, 32FR, 32RL, and 32RR. The four vehicle height adjustment valves 33 include vehicle height adjustment valves 33FL, 33FR, 33RL, and 33RR. Note that the common passage 31 is an example of the "oil passage" of the present invention.

[0025] The common passage 31 is arranged between the hydraulic fluid supply and discharge device 2 and the four individual passages 32. That is, the common passage 31 is connected to the hydraulic fluid supply and discharge device 2 and branched from the common passage 31 to the four individual passages 32. A temperature sensor 36 and a pressure sensor 37 are provided in the common passage 31.

[0026] The individual passage 32FL is provided to connect the hydraulic cylinder 1FL to the common passage 31. A vehicle height adjustment valve 33FL is provided in the individual passage 32FL. The vehicle height adjustment valve 33FL is, for example, a normally closed electromagnetic on-off valve and is provided to communicate or cut off the hydraulic cylinder 1FL from the common passage 31. The vehicle height adjustment valve 33FL is configured to open when supplying and discharging the hydraulic fluid of the hydraulic cylinder 1FL.

[0027] The individual passage 32FR is provided to connect the hydraulic cylinder 1FR to the common passage 31. A vehicle height adjustment valve 33FR is provided in the individual passage 32FR. The vehicle height adjustment valve 33FR is, for example, a normally closed electromagnetic on-off valve and is provided to communicate or cut off the hydraulic cylinder 1FR from the common passage 31. The vehicle height adjustment valve 33FR is configured to open when supplying and discharging the hydraulic fluid of the hydraulic cylinder 1FR.

[0028] The individual passage 32RL is provided to connect the hydraulic cylinder 1RL to the common passage 31. A vehicle height control valve 33RL is provided in the individual passage 32RL. The vehicle height control valve 33RL is, for example, a normally closed electromagnetic on-off valve, and is provided to communicate or cut off the hydraulic cylinder 1RL from the common passage 31. The vehicle height control valve 33RL is configured to open when the hydraulic oil of the hydraulic cylinder 1RL is supplied and discharged.

[0029] The individual passage 32RR is provided to connect the hydraulic cylinder 1RR to the common passage 31. A vehicle height control valve 33RR is provided in the individual passage 32RR. The vehicle height control valve 33RR is, for example, a normally closed electromagnetic on-off valve, and is provided to communicate or cut off the hydraulic cylinder 1RR from the common passage 31. The vehicle height control valve 33RR is configured to open when the hydraulic oil of the hydraulic cylinder 1RR is supplied and discharged.

[0030] The accumulator tank 34 is connected to the common passage 31 via the tank control valve 35. The accumulator tank 34 is provided to speed up the rise of the vehicle height. The tank control valve 35 is, for example, a normally closed electromagnetic on-off valve, and is provided to communicate or cut off the accumulator tank 34 from the common passage 31. The tank control valve 35 is configured to open when the hydraulic oil of the accumulator tank 34 is supplied and discharged.

[0031] As shown in FIG. 2, the accumulator tank 34 has a tank body 341 and a piston 342. The tank body 341 is formed in a cylindrical shape and has an internal space. The piston 342 is movably accommodated in the internal space of the tank body 341. The internal space of the tank body 341 is partitioned by the piston 342, and a gas chamber 343 and an oil chamber 344 are formed. The gas chamber 343 is filled with gas (for example, nitrogen gas). The oil chamber 344 is connected to the common passage 31 via the tank control valve 35. An annular groove is formed on the outer peripheral surface of the piston 342, and an O-ring 342a is mounted in the annular groove. The O-ring 342a is provided to seal the gap between the gas chamber 343 and the oil chamber 344.

[0032] And the accumulator tank 34 stores the hydraulic oil in the oil chamber 344 and is configured to be able to discharge the hydraulic oil in the oil chamber 344. During pressure accumulation, the piston 342 is moved to one side (the left side in FIG. 2), and during pressure release, the piston 342 is moved to the other side (the right side in FIG. 2).

[0033] As shown in FIG. 4, the ECU 4 includes an arithmetic unit 41, a storage unit 42, and an input / output unit 43. The storage unit 42 stores programs and the like for controlling the vehicle height adjustment system 100. The arithmetic unit 41 is configured to control the vehicle height adjustment system 100 by executing the programs stored in the storage unit 42. Connected to the input / output unit 43 are a temperature sensor 36, a pressure sensor 37, a vehicle height sensor (not shown), a brush motor 22, four vehicle height adjustment valves 33, and a tank control valve 35, etc.

[0034] The temperature sensor 36 is provided to detect the temperature (oil temperature) of the hydraulic oil in the common passage 31. The pressure sensor 37 is provided to detect the pressure (oil pressure) of the hydraulic oil in the common passage 31. The vehicle height sensor is provided to detect the distance between the wheel and the vehicle body. The ECU 4 is configured to control the brush motor 22, the four vehicle height adjustment valves 33, and the tank control valve 35 based on inputs from the vehicle height sensor and the like.

[0035] -Vehicle height raising and lowering operation- Next, an example of the vehicle height raising and lowering operation of the vehicle height adjustment system 100 will be described.

[0036] [When the vehicle height rises] When the vehicle height is increased, the ECU 4 drives the brush motor 22 to operate the oil pump 21. Also, the ECU 4 opens the tank control valve 35 and the four vehicle height adjustment valves 33. Therefore, the hydraulic oil discharged from at least one of the oil pump 21 and the accumulator tank 34 is supplied to the four hydraulic cylinders 1 via the hydraulic circuit 3. As a result, the four hydraulic cylinders 1 extend and the vehicle height increases. Then, when the vehicle height reaches the target value, the ECU 4 closes the four vehicle height adjustment valves 33.

[0037] Then, the hydraulic oil discharged from the oil pump 21 is supplied to the accumulator tank 34 via the common passage 31. Then, when the hydraulic pressure of the accumulator tank 34 reaches the target value, the ECU 4 closes the tank control valve 35 and stops the operation of the oil pump 21.

[0038] [When the vehicle height decreases] When the vehicle height is decreased, the ECU 4 opens the four vehicle height adjustment valves 33 while keeping the oil pump 21 stopped. Therefore, the hydraulic oil of the four hydraulic cylinders 1 is returned to the reservoir tank 23 via the hydraulic circuit 3 and the return valve 25. As a result, the four hydraulic cylinders 1 contract and the vehicle height decreases. Then, when the vehicle height reaches the target value, the ECU 4 closes the four vehicle height adjustment valves 33.

[0039] -Judgment of the life of the accumulator tank- Here, in the accumulator tank 34, when the piston 342 moves, the O-ring 342a slides and wears. Therefore, the O-ring 342a is likely to deteriorate in the accumulator tank 34. Therefore, the ECU 4 is configured to estimate the degree of deterioration of the O-ring 342a and judge the life of the accumulator tank 34.

[0040] The ECU 4 is configured to calculate the volume change ΔV of the gas chamber 343 during pressure accumulation. Further, the ECU 4 is configured to calculate the movement amount AM of the piston 342 during pressure accumulation based on the volume change ΔV of the gas chamber 343. Furthermore, the ECU 4 is configured to determine the life of the accumulator tank 34 based on the integrated value of the calculated movement amount AM. Note that by executing the program stored in the storage unit 42 by the calculation unit 41, the "volume change calculation unit", "movement amount calculation unit", and "life determination unit" of the present invention are realized.

[0041] Specifically, the storage unit 42 of the ECU 4 stores information regarding the accumulator tank 34. The information regarding the accumulator tank 34 includes the volume Vi, the pressure Pi, the temperature Ti, and the piston area AP. The volume Vi is the volume of the gas chamber 343 when the accumulator tank 34 is in the initial state. The pressure Pi is the pressure of the gas chamber 343 when the accumulator tank 34 is in the initial state. The temperature Ti is the temperature of the gas chamber 343 when the accumulator tank 34 is in the initial state. The piston area AP is the pressure receiving area of the piston 342. The volume Vi, the pressure Pi, the temperature Ti, and the piston area AP are preset values. Note that when the accumulator tank 34 is in the initial state, as shown in FIG. 3, the piston 342 is arranged at the other end.

[0042] The calculation of the volume change ΔV by the ECU 4 is performed using the following formula (1).

[0043] ΔV = Vb - Va ···(1) In formula (1), Va is the volume of the gas chamber 343 after pressure accumulation, and Vb is the volume of the gas chamber 343 before pressure accumulation. The calculation of the volume Va is performed using the following formula (2), and the calculation of the volume Vb is performed using the following formula (3).

[0044] Va = (Pi × Vi × Ta) / (Ti × Pa) ···(2) Vb = (Pi × Vi × Tb) / (Ti × Pb) ···(3) In Equation (2), Pa is the pressure of the gas chamber 343 after pressure accumulation, and Ta is the temperature of the gas chamber 343 after pressure accumulation. In Equation (3), Pb is the pressure of the gas chamber 343 before pressure accumulation, and Tb is the temperature of the gas chamber 343 before pressure accumulation. The pressure Pa is estimated, for example, based on the detection result of the pressure sensor 37 after pressure accumulation. The temperature Ta is estimated, for example, based on the detection result of the temperature sensor 36 after pressure accumulation. The pressure Pb is estimated, for example, based on the detection result of the pressure sensor 37 before pressure accumulation. The temperature Tb is estimated, for example, based on the detection result of the temperature sensor 36 before pressure accumulation.

[0045] Also, in Equations (2) and (3), Vi is the volume of the gas chamber 343 in the initial state, Pi is the pressure of the gas chamber 343 in the initial state, and Ti is the temperature of the gas chamber 343 in the initial state. The volume Vi, the pressure Pi, and the temperature Ti are stored in advance in the storage unit 42.

[0046] Also, the calculation of the movement amount AM by the ECU 4 is performed using the following Equation (4).

[0047] AM = ΔV / AP ···(4) In Equation (4), ΔV is the volume change of the gas chamber 343 before and after pressure accumulation, and AP is the pressure receiving area of the piston 342. The volume change ΔV is calculated using Equation (1). The piston area AP is stored in advance in the storage unit 42.

[0048] Also, the storage unit 42 stores operation history information 42a. The calculated movement amount AM is accumulated in the operation history information 42a. That is, each time pressure accumulation is performed, the movement amount AM is stored in the operation history information 42a. And the ECU 4 is configured to determine that the life of the accumulator tank 34 has come when the integrated value of the movement amount AM exceeds a threshold value. This threshold value is a value preset based on experiments, simulations, etc.

[0049] [Accumulation operation of operation history] Next, with reference to FIG. 5, the operation of accumulating the operation history of the accumulator tank 34 by the ECU 4 will be described.

[0050] First, in step ST1 of FIG. 5, the ECU 4 determines whether or not the pressure accumulation of the accumulator tank 34 has started. Whether or not the pressure accumulation has started is determined based on, for example, the detection result of the pressure sensor 37. When the ECU 4 determines that the pressure accumulation has started, the process proceeds to step ST2. On the other hand, when the ECU 4 determines that the pressure accumulation has not started, step ST1 is repeated. That is, the process waits until the pressure accumulation starts.

[0051] Next, in step ST2, the ECU 4 acquires the oil temperature and the oil pressure using the temperature sensor 36 and the pressure sensor 37. Based on this oil temperature, the temperature Tb of the gas chamber 343 before the pressure accumulation is estimated. Based on this oil pressure, the pressure Pb of the gas chamber 343 before the pressure accumulation is estimated.

[0052] Next, in step ST3, the ECU 4 determines whether or not the pressure accumulation of the accumulator tank 34 has ended. Whether or not the pressure accumulation has ended is determined based on, for example, the detection result of the pressure sensor 37. When the ECU 4 determines that the pressure accumulation has ended, the process proceeds to step ST4. On the other hand, when the ECU 4 determines that the pressure accumulation has not ended, step ST3 is repeated. That is, when the accumulator tank 34 is in the process of pressure accumulation, step ST3 is repeated. That is, the process waits until the pressure accumulation ends.

[0053] Next, in step ST4, the ECU 4 acquires the oil temperature and the oil pressure using the temperature sensor 36 and the pressure sensor 37. Based on this oil temperature, the temperature Ta of the gas chamber 343 after the pressure accumulation is estimated. Based on this oil pressure, the pressure Pa of the gas chamber 343 after the pressure accumulation is estimated.

[0054] Next, in step ST5, the ECU 4 calculates the volume change ΔV of the gas chamber 343 during pressure accumulation. The volume change ΔV is calculated using the temperature Tb and pressure Pb estimated in step ST2 and the temperature Ta and pressure Pa estimated in step ST4. Specifically, the volume change ΔV is calculated based on the above-described equations (1) to (3).

[0055] Next, in step ST6, the ECU 4 calculates the movement amount AM of the piston 342 during pressure accumulation. The movement amount AM is calculated using the volume change ΔV calculated in step ST5. Specifically, the movement amount AM is calculated based on the above-described equation (4).

[0056] Next, in step ST7, the ECU 4 stores the movement amount AM in the operation history information 42a. Then, the process returns.

[0057] [Life Judgment Operation] Next, with reference to FIG. 6, the life judgment operation of the pressure accumulation tank 34 by the ECU 4 will be described.

[0058] First, in step ST11 of FIG. 6, the ECU 4 determines whether or not a predetermined period has elapsed. This predetermined period is a preset period, for example, one day. When the ECU 4 determines that the predetermined period has elapsed, the process proceeds to step ST12. On the other hand, when the ECU 4 determines that the predetermined period has not elapsed, step ST11 is repeated. That is, the process waits until the predetermined period elapses. That is, step ST12 described below is performed every predetermined period.

[0059] Next, in step ST12, the ECU 4 determines whether or not the integrated value of the movement amount AM exceeds a threshold value. The integrated value of the movement amount AM is calculated based on the operation history information 42a. That is, the integrated value of the movement amount AM is a value obtained by accumulating the movement amount AM calculated each time pressure accumulation is performed. When it is determined by the ECU 4 that the integrated value of the movement amount AM exceeds the threshold value, the process proceeds to step ST13. On the other hand, when it is determined by the ECU 4 that the integrated value of the movement amount AM does not exceed the threshold value, the process returns to step ST11.

[0060] In step ST13, the ECU 4 determines that the life of the accumulator tank 34 has come. In this case, the ECU 4 uses a notification device (not shown) to notify the user that the life of the accumulator tank 34 has come. Thereby, it is possible to prompt the user to replace the accumulator tank 34 whose life has come.

[0061] -Effect- In the present embodiment, as described above, the movement amount AM of the piston 342 is calculated based on the volume change ΔV of the gas chamber 343, and the life of the accumulator tank 34 is determined based on the integrated value of the movement amount AM. By configuring in this way, the life of the accumulator tank 34 can be determined based on the movement amount AM of the piston 342. And by determining the life of the accumulator tank 34, the accumulator tank 34 can be used up appropriately.

[0062] Further, in the present embodiment, the volume Va of the gas chamber 343 after pressure accumulation is calculated based on the pressure Pa of the gas chamber 343 after pressure accumulation and the temperature Ta of the gas chamber 343 after pressure accumulation. Also, the volume Vb of the gas chamber 343 before pressure accumulation is calculated based on the pressure Pb of the gas chamber 343 before pressure accumulation and the temperature Tb of the gas chamber 343 before pressure accumulation. Then, the volume change ΔV of the gas chamber 343 is calculated by subtracting the volume Va of the gas chamber 343 after pressure accumulation from the volume Vb of the gas chamber 343 before pressure accumulation. By configuring in this way, the volume change ΔV of the gas chamber 343 during pressure accumulation can be calculated.

[0063] In addition, in the present embodiment, the temperature of the gas chamber 343 is estimated based on the detection result of the temperature sensor 36, and the pressure of the gas chamber 343 is estimated based on the detection result of the pressure sensor 37. By configuring in this way, it is possible to suppress an increase in the number of components compared to the case where a temperature sensor for detecting the temperature of the gas chamber is provided or the case where a pressure sensor for detecting the pressure of the gas chamber is provided.

[0064] -Other Embodiments- Note that the embodiments disclosed this time are illustrative in all respects and are not a basis for limiting interpretation. Therefore, the technical scope of the present invention is not interpreted only by the above-described embodiments, but is defined based on the description in the claims. Further, the technical scope of the present invention includes all modifications within the meaning and scope equivalent to the claims.

[0065] For example, in the above embodiment, an example in which the life determination operation (see FIG. 6) is executed by the ECU 4 is shown. However, the present invention is not limited to this, and the life determination operation may be executed by a server device (not shown) by the ECU transmitting the operation history information to the server device.

[0066] In addition, in the above embodiment, an example in which the movement amount AM of the piston 342 during pressure accumulation is integrated is shown. However, the present invention is not limited to this, and the movement amount of the piston during pressure accumulation and the movement amount of the piston during pressure release may be integrated.

[0067] In addition, in the above embodiment, an example in which the temperature of the gas chamber 343 is estimated based on the detection result of the temperature sensor 36 and the pressure of the gas chamber 343 is estimated based on the detection result of the pressure sensor 37 is shown. However, the present invention is not limited to this, and a temperature sensor for detecting the temperature of the gas chamber may be provided, or a pressure sensor for detecting the pressure of the gas chamber may be provided.

Industrial Applicability

[0068] The present invention can be used for a life determination device and a life determination method for determining the life of a pressure accumulation tank.

Explanation of Reference Numerals

[0069] 4 ECU (Life Judgment Device) 31 Common Passage (Oil Passage) 34 Accumulator Tank 36 Temperature Sensor 37 Pressure Sensor 100 Vehicle Height Adjustment System 342 Piston 343 Gas Chamber 344 Oil Chamber

Claims

1. A life determination device for determining the life of a pressure accumulator tank, wherein the pressure accumulator tank has a gas chamber filled with gas, an oil chamber connected to an oil passage, and a piston partitioning the gas chamber and the oil chamber, the pressure accumulator tank stores hydraulic oil in the oil chamber and is configured to be able to discharge the hydraulic oil in the oil chamber, a movement amount calculation unit that calculates the movement amount of the piston based on the volume change of the gas chamber, and a life determination unit that determines that the life of the pressure accumulator tank has arrived when the integrated value of the movement amount calculated by the movement amount calculation unit exceeds a threshold value. The life determination device is characterized by comprising the above.

2. In the life determination device according to Claim 1, it comprises a volume change calculation unit that calculates the volume change of the gas chamber, and the volume change calculation unit is configured to calculate the volume change of the gas chamber based on the temperature of the gas chamber before pressure accumulation, the pressure of the gas chamber before pressure accumulation, the temperature of the gas chamber after pressure accumulation, and the pressure of the gas chamber after pressure accumulation. The life determination device is characterized by this.

3. In the life determination device according to Claim 2, the oil passage is a common passage of a vehicle height adjustment system, a temperature sensor for detecting the temperature of the hydraulic oil and a pressure sensor for detecting the pressure of the hydraulic oil are provided in the common passage, the temperature of the gas chamber is estimated based on the detection result of the temperature sensor, and the pressure of the gas chamber is estimated based on the detection result of the pressure sensor. The life determination device is characterized by this.

4. A life determination method for determining the life of a pressure accumulator tank, wherein the pressure accumulator tank has a gas chamber filled with gas, an oil chamber connected to an oil passage, and a piston partitioning the gas chamber and the oil chamber, the pressure accumulator tank stores hydraulic oil in the oil chamber and is configured to be able to discharge the hydraulic oil in the oil chamber, a step of calculating the movement amount of the piston based on the volume change of the gas chamber, and a step of determining that the life of the pressure accumulator tank has arrived when the integrated value of the calculated movement amount exceeds a threshold value. The life determination method is characterized by comprising the above.

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