Hydraulic circuit system with abnormality diagnosis function and steering device equipped with same

Abstract

To provide a hydraulic circuit system with an abnormality diagnosis function that can determine an abnormality of a hydraulic circuit.SOLUTION: A hydraulic circuit system with an abnormality diagnosis function comprises at least one positive displacement pump, a hydraulic circuit connected to the pump, a downstream side sensor for detecting a state quantity of hydraulic liquid flowing on the downstream side of the hydraulic circuit, and an abnormality diagnosis device for determining an abnormality of the hydraulic circuit on the basis of a first state quantity of the hydraulic liquid discharged from the pump, and a second state quantity of the hydraulic liquid detected by the downstream side sensor.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a hydraulic circuit system with an abnormality diagnosis function that determines an abnormality in a hydraulic circuit, and a steering device including the same. [Background technology]

[0002] Positive displacement pumps such as swash plate pumps are widely used in industrial machinery such as marine machinery and construction machinery. As an abnormality diagnosis device for detecting abnormalities in positive displacement pumps, for example, a fault diagnosis device such as that disclosed in Patent Document 1 is known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6340121 Specification Summary of the Invention [Problem to be solved by the invention]

[0004] The failure diagnosis device of Patent Document 1 can diagnose failures in a positive displacement pump based on the suction pressure of the hydraulic fluid, but is not intended to determine abnormalities in a hydraulic circuit connected to the pump.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a hydraulic circuit system with an abnormality diagnosis function that can determine an abnormality in the hydraulic circuit, and a steering device equipped with the same. [Means for solving the problem]

[0006] The hydraulic circuit system of the present invention comprises at least one positive displacement pump, a hydraulic circuit connected to the pump, a downstream sensor that detects a state quantity of hydraulic fluid flowing downstream of the hydraulic circuit, and an abnormality diagnosis device that determines an abnormality in the hydraulic circuit based on the result of comparing a first state quantity of the hydraulic fluid discharged from the pump with a second state quantity of the hydraulic fluid detected by the downstream sensor.

[0007] According to the present invention, a change in the state quantity of the hydraulic fluid flowing through the hydraulic circuit can be detected based on the first state quantity of the hydraulic fluid discharged from the pump and the second state quantity of the hydraulic fluid detected by the downstream sensor, and an abnormality in the hydraulic circuit can be determined based on the change in hydraulic pressure.

[0008] The steering device of the present invention includes the above-described hydraulic circuit system with an abnormality diagnosis function.

[0009] According to the present invention, a steering device having the above-described functions can be realized. [Effects of the Invention]

[0010] According to the present invention, it is possible to determine whether there is an abnormality in the hydraulic circuit. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a circuit diagram showing a hydraulic circuit system with an abnormality diagnosis function according to a first embodiment of the present invention. [Figure 2] 2 is a graph showing the change over time in pressure detected by each sensor in the hydraulic circuit system with an abnormality diagnosis function of FIG. 1, where (a) is the change over time in pressure detected by each sensor under normal conditions when the pump is operating, and (b) is the change over time in pressure detected by each sensor under normal conditions when the pump is stopped. [Figure 3] 2 is a graph showing the change over time in pressure detected by each sensor in the hydraulic circuit system with abnormality diagnosis function of FIG. 1, where (a) is the change over time in pressure detected by each sensor when the second shutoff valve is stuck in the closed position, and (b) is the change over time in pressure detected by each sensor when hydraulic fluid is leaking. [Figure 4] FIG. 4 is a circuit diagram showing a hydraulic circuit system with an abnormality diagnosis function according to a second embodiment of the present invention. [Figure 5] 5 is a graph showing changes over time in pressure detected by each sensor when the hydraulic circuit is normal in the hydraulic circuit system with an abnormality diagnosis function of FIG. 4. [Figure 6]5 is a graph showing changes over time in pressure detected by each sensor when an abnormality occurs in the hydraulic circuit in the hydraulic circuit system with an abnormality diagnosis function of FIG. 4. [Figure 7] FIG. 10 is a circuit diagram showing a hydraulic circuit system with an abnormality diagnosis function according to a third embodiment of the present invention. [Figure 8] 8A and 8B are graphs showing the results of frequency analysis of downstream pressure waveform data in the hydraulic circuit system with an abnormality diagnosis function shown in FIG. 7, where (a) is the frequency analysis result when the hydraulic circuit is normal, and (b) is the frequency analysis result when the hydraulic circuit is abnormal. [Figure 9] FIG. 10 is a circuit diagram showing a hydraulic circuit system with an abnormality diagnosis function according to a fourth embodiment of the present invention. [Figure 10] FIG. 10 is a circuit diagram showing a hydraulic circuit system with an abnormality diagnosis function according to a fifth embodiment of the present invention. [Figure 11] FIG. 10 is a circuit diagram showing a steering device including a hydraulic circuit system with an abnormality diagnosis function according to a sixth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, hydraulic circuit systems with an abnormality diagnosis function (hereinafter referred to as "hydraulic circuit systems") 1, 1A to 1E according to first to sixth embodiments of the present invention and a steering device 2 equipped with the same will be described with reference to the drawings. Note that the concept of direction used in the following description is used for the convenience of explanation and does not limit the orientation of the configuration of the invention to that direction. Furthermore, the hydraulic circuit systems 1, 1A to 1E and the steering device 2 described below are merely one embodiment of the present invention. Therefore, the present invention is not limited to the embodiments, and additions, deletions, and modifications are possible within the scope of the invention.

[0013] <Hydraulic circuit system> A hydraulic circuit system 1 as shown in FIG. 1 drives a hydraulic actuator 3 by supplying hydraulic fluid (e.g., oil and water) to the hydraulic actuator 3. The hydraulic actuator 3 is, for example, a hydraulic cylinder and a hydraulic motor. The hydraulic circuit system 1 can also diagnose abnormalities within the hydraulic circuit system 1. The hydraulic circuit system 1 includes a hydraulic pump 11, a hydraulic circuit 12, a downstream sensor 13, and a control device 14. The hydraulic circuit system 1 also includes an upstream sensor 15.

[0014] <Hydraulic pump> The hydraulic pump 11 discharges hydraulic fluid. The hydraulic pump 11 is a positive displacement hydraulic pump. That is, the hydraulic fluid discharged from the hydraulic pump 11 pulsates. The hydraulic pump 11 is, for example, a reciprocating pump (such as a swash plate pump, a bent axis pump, or a piston pump), a gear pump, or a trochoid pump. In this embodiment, the hydraulic pump 11 is a swash plate pump.

[0015] <Hydraulic circuit> The hydraulic circuit 12 is connected to the hydraulic pump 11 and the hydraulic actuator 3. The hydraulic circuit 12 supplies the hydraulic fluid discharged from the hydraulic pump 11 to the hydraulic actuator 3. The hydraulic circuit 12 controls the flow of the hydraulic fluid supplied from the hydraulic pump 11 to the actuator 3. The hydraulic circuit 12 includes a fluid passage 21, a plurality of shut-off valves 22, 23, and a relief valve 24. Note that the hydraulic circuit 12 may include components other than those shown in FIG. 1. Examples of other components included in the hydraulic circuit 12 include valves such as directional control valves, check valves, and control valves, as well as throttles.

[0016] The fluid passage 21 is connected to the hydraulic pump 11 and the hydraulic actuator 3. The fluid passage 21 supplies the hydraulic fluid discharged from the hydraulic pump 11 to the hydraulic actuator 3. A plurality of shutoff valves 22, 23, which are an example of hydraulic control devices, are disposed in series in the fluid passage 21. In this embodiment, two shutoff valves 22, 23 are disposed in the fluid passage 21. The shutoff valve 22 located upstream in the fluid passage 21 is a first shutoff valve 22, and the shutoff valve 23 located downstream is a second shutoff valve 23. The two shutoff valves 22, 23 are, for example, normally open shutoff valves. That is, the shutoff valves 22, 23 close the fluid passage 21 in response to an input control signal. The two shutoff valves 22, 23 may be normally closed shutoff valves. A relief valve 24 is connected to the fluid passage 21. More specifically, the relief valve 24 is connected to the fluid passage 21 downstream of the two shutoff valves 22, 23. The relief valve 24 discharges the hydraulic fluid in the fluid passage 21 to the tank 25 when the fluid pressure in the fluid passage 21 exceeds a predetermined pressure.

[0017] <Upstream sensor> The upstream sensor 15 detects a first state quantity of the hydraulic fluid discharged from the hydraulic pump 11. The upstream sensor 15 is disposed upstream of the hydraulic circuit 12. More specifically, the upstream sensor 15 is connected upstream of the two shut-off valves 22, 23 in the fluid passage 21. In this embodiment, the upstream sensor 15 is a hydraulic pressure sensor, and detects the hydraulic pressure of the hydraulic fluid discharged from the hydraulic pump 11, i.e., the discharge pressure. The upstream sensor 15 may also be a flow rate sensor. In this case, the upstream sensor 15 detects the flow rate as the first state quantity.

[0018] <Downstream sensor> The downstream sensor 13 detects a second state quantity of the hydraulic fluid flowing downstream of the hydraulic circuit 12. The downstream sensor 13 is arranged downstream of the hydraulic circuit 12. More specifically, the downstream sensor 13 is connected downstream of the two shutoff valves 22, 23 in the hydraulic passage 21. Furthermore, the downstream sensor 13 is connected downstream of the relief valve 24 in the hydraulic passage 21. In this embodiment, the downstream sensor 13 is a hydraulic pressure sensor that detects the hydraulic pressure downstream of the hydraulic circuit 12, i.e., the downstream pressure. Note that the downstream sensor 13 may be a flow rate sensor. In this case, the downstream sensor 13 detects the flow rate as the second state quantity.

[0019] <Control device> The control device 14 outputs control signals to the shutoff valves 22, 23. The control device 14 controls the operation of the shutoff valves 22, 23 by outputting control signals to the shutoff valves 22, 23. More specifically, the control device 14 operates the first shutoff valve 22 by outputting a first control signal. The control device 14 also operates the second shutoff valve 23 by outputting a second control signal. The control device 14 then closes the liquid passage 21 by operating either the shutoff valve 22 or 23.

[0020] Furthermore, the control device 14, which is an example of an abnormality diagnosis device, determines an abnormality in the hydraulic circuit 12 based on the discharge pressure of the hydraulic pump 11 and the downstream pressure detected by the downstream sensor 13. More specifically, the control device 14 acquires the discharge pressure and the downstream pressure from the respective sensors 13, 15. The control device 14 compares the acquired downstream pressure and discharge pressure and determines an abnormality in the hydraulic circuit 12 based on the comparison result. In this embodiment, the control device 14 determines an abnormality in the hydraulic circuit 12 based on the comparison result of the waveform data of the discharge pressure and the waveform data of the downstream pressure.

[0021] <Operation of the hydraulic circuit system> In the hydraulic circuit system 1, when no control signal is output from the control device 14 to the shutoff valves 22, 23 (i.e., when this state is referred to as the "de-energized state"), the fluid passage 21 is open. Therefore, the hydraulic fluid discharged from the hydraulic pump 11 is supplied to the hydraulic actuator 3. This causes the hydraulic actuator 3 to operate.

[0022] Next, the control device 14 outputs at least one of a first and a second control signal based on a program or a command from an operating device (not shown) (hereinafter referred to as "program, etc."). The operating device is, for example, a lever, a switch, a touch panel, etc., which is operated to output a command signal (electrical signal, hydraulic signal, etc.). The first shut-off valve 22 closes the fluid passage 21 when the first control signal is output from the control device 14. Furthermore, the second shut-off valve 23 closes the fluid passage 21 when the second control signal is output from the control device 14. When at least one of the shut-off valves 22, 23 closes the fluid passage 21, the operation of the hydraulic actuator 3 stops.

[0023] <Fault diagnosis of hydraulic circuit systems> In the hydraulic circuit system 1, the control device 14 diagnoses an abnormality in the hydraulic circuit 12 based on the discharge pressure and the downstream pressure. More specifically, the control device 14 diagnoses an abnormality in the hydraulic circuit 12 based on the comparison result between the discharge pressure and the downstream pressure. In this embodiment, the control device 14 diagnoses an abnormality in the hydraulic circuit 12 based on a control signal, waveform data of the discharge pressure, and waveform data of the downstream pressure. The abnormality diagnosis method will be described in further detail below.

[0024] In the hydraulic circuit system 1, the control device 14 acquires the discharge pressure from the upstream sensor 15 and the downstream pressure from the downstream sensor 13 in each of the de-energized state and the stopped state in which the hydraulic pump 11 is stopped. The control device 14 generates waveform data of the discharge pressure, which is a change in the discharge pressure over time, from the acquired discharge pressure. The control device 14 also generates waveform data of the downstream pressure, which is a change in the downstream pressure over time, from the acquired downstream pressure. The control device 14 then compares the waveform data of the discharge pressure generated in each of the de-energized state and the stopped state with the waveform data of the discharge pressure. The control device 14 diagnoses an abnormality in the hydraulic circuit 12 based on the comparison result.

[0025] In a non-energized state, for example, the control device 14 generates waveform data of the discharge pressure and waveform data of the downstream pressure as shown in FIG. 2(a). That is, the generated waveform data of the discharge pressure and waveform data of the downstream pressure both pulsate (see "waveform data of the discharge pressure" and "waveform data of the downstream pressure" in FIG. 2(a)). The control device 14 determines that the two waveform data are identical based on the comparison result of the two generated waveform data. As a result, the control device 14 determines that both the shutoff valves 22 and 23 are operating normally.

[0026] Similarly, in a stopped state, the control device 14 generates waveform data of the discharge pressure and waveform data of the downstream pressure, for example, as shown in FIG. 2(b). The generated waveform data of the discharge pressure and waveform data of the downstream pressure are both constant pressures (e.g., tank pressure) (see "waveform data of discharge pressure" and "waveform data of downstream pressure" in FIG. 2(b)). The control device 14 determines that the two waveform data are identical based on the comparison results of the two generated waveform data. As a result, the control device 14 determines that both the shutoff valves 22 and 23 are operating normally.

[0027] On the other hand, in the hydraulic circuit system 1, the control device 14 may generate waveform data of the discharge pressure and waveform data of the downstream pressure as shown in FIG. 3(a) when the power is off. That is, the generated waveform data of the discharge pressure pulsates (see “Discharge Pressure Waveform Data” in FIG. 3(a)). On the other hand, the generated waveform data of the downstream pressure is a constant pressure (tank pressure) (see “Downstream Pressure Waveform Data” solid line in FIG. 3(a)), unlike the waveform data of the downstream pressure under normal conditions (see “Downstream Pressure Waveform Data” dashed line in FIG. 3(a)). If the two waveform data are different and the downstream pressure is constant when no control signal is output, the control device 14 determines that the hydraulic circuit 12 is abnormal based on the control signal and the two waveform data. More specifically, the control device 14 determines that one of the shutoff valves 22, 23 is stuck in a closed state, closing the hydraulic passage 21. In this way, the control device 14 can diagnose abnormalities in the response of the shutoff valves 22, 23 to the control signal.

[0028] Furthermore, in a non-energized state, the control device 14 may generate waveform data of the discharge pressure and waveform data of the downstream pressure, such as those shown in Figure 3(b). That is, the waveform data of the downstream pressure is significantly attenuated (see the solid line and the two-dot chain line of the "waveform data of the downstream pressure" in Figure 3(b)) compared to the waveform data of the discharge pressure generated (see "waveform data of the discharge pressure" in Figure 3(b)). In this case, the control device 14 diagnoses that the hydraulic circuit 12 is abnormal. More specifically, the control device 14 diagnoses that a liquid leak is occurring in the liquid passage 21.

[0029] In the hydraulic circuit system 1 of the first embodiment, a change in the hydraulic pressure of the hydraulic fluid flowing through the hydraulic circuit 12 can be detected based on the discharge pressure of the hydraulic pump 11 and the downstream pressure detected by the downstream sensor 13. Then, an abnormality in the hydraulic circuit 12 can be determined based on the change in hydraulic pressure. This makes it easy to determine an abnormality in the hydraulic circuit 12.

[0030] In the hydraulic circuit system 1 of the first embodiment, the hydraulic circuit 12 includes shutoff valves 22 and 23. The control device 14 can determine whether there is an abnormality in the shutoff valves 22 and 23 included in the hydraulic circuit 12 by detecting a change in the pressure of the hydraulic fluid flowing through the shutoff valves 22 and 23 based on the discharge pressure and the downstream pressure.

[0031] Furthermore, in the hydraulic circuit system 1 of the first embodiment, the control device 14 determines whether there is an abnormality in the shutoff valves 22, 23 based on the control signal, the discharge pressure, and the downstream pressure. Therefore, the control device 14 can determine whether there is an abnormality in the response of the shutoff valves 22, 23 to the control signal.

[0032] Furthermore, in the hydraulic circuit system 1 of the first embodiment, the control device 14 determines whether there is an abnormality in the hydraulic circuit 12 based on the waveform data of the discharge pressure and the waveform data of the downstream pressure. Qualitative changes in the downstream pressure relative to the discharge pressure can be more easily detected when diagnosing based on the waveform data of the discharge pressure and the downstream pressure than when diagnosing based solely on the discharge pressure and the downstream pressure. Therefore, the control device 14 can more easily determine whether there is an abnormality in the hydraulic circuit 12.

[0033] In the hydraulic circuit system 1 of the first embodiment, both the discharge pressure and the downstream pressure are detected by the sensors 15 and 13. The control device 14 determines whether there is an abnormality in the hydraulic circuit 12 based on the actual discharge pressure and downstream pressure, which are hydraulic pressures on the upstream side of the hydraulic circuit 12. This allows the control device 14 to improve the accuracy in determining whether there is an abnormality in the hydraulic circuit 12.

[0034] Second Embodiment The hydraulic circuit system 1A of the second embodiment is similar in configuration to the hydraulic circuit system 1 of the first embodiment. Therefore, the configuration of the hydraulic circuit system 1A of the second embodiment will be mainly described in terms of differences from the hydraulic circuit system 1A of the first embodiment, and the same components will be assigned the same reference numerals and descriptions thereof will be omitted. Similarly, the same components will be assigned the same reference numerals and descriptions thereof will be omitted for the hydraulic circuit systems 1B to 1E of the third to sixth embodiments.

[0035] 4, the hydraulic circuit system 1A of the second embodiment includes a plurality of hydraulic pumps 11, 11A, a hydraulic circuit 12A, a downstream sensor 13A, and a control device 14A. The hydraulic circuit system 1A also includes a plurality of upstream sensors 15, 15A.

[0036] <Hydraulic pump> The multiple hydraulic pumps 11, 11A all discharge hydraulic fluid. In this embodiment, a first hydraulic pump 11 and a second hydraulic pump 11A are provided in the hydraulic circuit system 1A. The second hydraulic pump 11A is a positive displacement hydraulic pump like the first hydraulic pump 11. That is, the hydraulic fluid discharged by the second hydraulic pump 11A also pulsates. The second hydraulic pump 11A is, for example, a reciprocating pump (such as a swash plate pump, a bent axis pump, or a piston pump), a gear pump, or a trochoid pump. In this embodiment, the second hydraulic pump 11A is also a swash plate pump.

[0037] <Hydraulic circuit> The hydraulic circuit 12A is connected to both hydraulic pumps 11, 11A. The hydraulic circuit 12A is also connected to the hydraulic actuator 3. The hydraulic circuit 12A merges the hydraulic fluids flowing from the two hydraulic pumps 11, 11A. The hydraulic circuit 12A then supplies the merged hydraulic fluid to the hydraulic actuator 3. The hydraulic circuit 12A also controls the flow of the hydraulic fluid supplied from the hydraulic pumps 11, 11A to the hydraulic actuator 3. The hydraulic circuit 12A has a plurality of circuit systems 31, 31A, a merge passage 33, and a relief valve 24.

[0038] Each of the multiple circuit systems 31, 31A is connected to a respective hydraulic pump 11, 11A. In this embodiment, the hydraulic circuit 12A has two circuit systems 31, 31A, the same number as the hydraulic pumps 11, 11A. One of the circuit systems 31, the first circuit system 31, is connected to the first hydraulic pump 11, and the other circuit system 31A, the second circuit system 31A, is connected to the second hydraulic pump 11A. Hydraulic fluid discharged from the connected hydraulic pumps 11, 11A flows through the circuit systems 31, 31A. The circuit systems 31, 31A control the flow of hydraulic fluid flowing through the circuit systems 31, 31A. The circuit systems 31, 31A have the same configuration in this embodiment.

[0039] The first circuit system 31 includes, for example, a first fluid passage 21 and a first directional control valve 34. The first circuit system 31 may include components other than those shown in Fig. 4. Examples of other components included in the first circuit system 31 include a shutoff valve, a check valve, a throttle, and a control valve.

[0040] The first fluid passage 21 is connected to the first hydraulic pump 11. Hydraulic fluid is discharged from the first hydraulic pump 11 to the first fluid passage 21. A first directional control valve 34, which is an example of a hydraulic control device, is interposed in the first fluid passage 21. The first directional control valve 34 controls the flow in the first fluid passage 21 in response to an input first control signal. More specifically, the first directional control valve 34 closes the first fluid passage 21 in response to the input first control signal. This stops the flow downstream in the first fluid passage 21.

[0041] The second circuit system 31A includes a second fluid passage 21A and a second directional control valve 34A. Like the first circuit system 31, the second circuit system 31A may also include components other than those shown in FIG.

[0042] The second fluid passage 21A is connected to the second hydraulic pump 11A. Hydraulic fluid is discharged from the second hydraulic pump 11A to the second fluid passage 21A. A second directional control valve 34A, which is an example of a hydraulic control device, is disposed in the second fluid passage 21A. The second directional control valve 34A also closes the second fluid passage 21A in response to an input second control signal. This stops the flow of fluid downstream in the second fluid passage 21A.

[0043] The junction passage 33 is connected to the two circuit systems 31, 31A. The hydraulic fluids flowing through the two circuit systems 31, 31A join in the junction passage 33. More specifically, the junction passage 33 is connected to the first fluid passage 21 of the first circuit system 31 and the second fluid passage 21A of the second circuit system 31A. The hydraulic fluids of the hydraulic pumps 11, 11A flowing through the two fluid passages 21, 21A join in the junction passage 33. The hydraulic actuator 3 is also connected to the junction passage 33. Therefore, the hydraulic fluids of the two hydraulic pumps 11, 11A can be joined in the junction passage 33 and then flow to the hydraulic actuator 3. A relief valve 24 is connected to the junction passage 33 downstream of a junction point 33a where the hydraulic fluids of the two hydraulic pumps 11, 11A join.

[0044] <Upstream sensor> The upstream sensors 15, 15A detect first state quantities of the hydraulic fluid discharged from the hydraulic pumps 11, 11A, respectively. In this embodiment, the hydraulic circuit system 1A includes two upstream sensors 15, 15A, the same number as the hydraulic pumps 11, 11A. One of the upstream sensors 15, the first upstream sensor 15, is connected to the upstream side of the first direction control valve 34 in the first fluid passage 21. The other upstream sensor 15A, the second upstream sensor 15A, is connected to the upstream side of the second direction control valve 34A in the second fluid passage 21A. More specifically, each of the upstream sensors 15, 15A is located at the most upstream side in its corresponding fluid passage 21, 21A. In this embodiment, the upstream sensors 15, 15A are hydraulic pressure sensors that detect the discharge pressures of the hydraulic pumps 11, 11A, respectively. The upstream sensors 15, 15A may be flow rate sensors.

[0045] <Downstream sensor> The downstream sensor 13A detects a second state quantity of the hydraulic fluid flowing downstream of the hydraulic circuit 12A. The downstream sensor 13A is connected downstream of the junction point 33a in the junction passage 33. In this embodiment, the downstream sensor 13A is a pressure sensor, and detects the downstream pressure, which is the hydraulic pressure of the hydraulic fluid flowing downstream of the junction passage 33. The downstream sensor 13A may also be a flow rate sensor.

[0046] <Control device> The control device 14A outputs control signals to the directional control valves 34, 34A. The control device 14 controls the operation of the directional control valves 34, 34A by outputting control signals to the directional control valves 34, 34A. More specifically, the control device 14 outputs a first control signal and a second control signal according to a program or the like. This causes the first directional control valve 34 and the second directional control valve 34A to operate.

[0047] Furthermore, the control device 14A, which is an example of an abnormality diagnosis device, determines an abnormality in the hydraulic circuit 12A based on the discharge pressures of the two hydraulic pumps 11, 11A and the downstream pressure detected by the downstream sensor 13A. More specifically, the control device 14A acquires the discharge pressures from the two upstream sensors 15, 15A and the downstream pressure from the downstream sensor 13A. The control device 14A then compares the two acquired discharge pressures with the downstream pressure and determines an abnormality in the hydraulic circuit 12A based on the comparison result. In this embodiment, the control device 14A determines an abnormality in the hydraulic circuit 12A (more specifically, an abnormality in the circuit systems 31, 31A) based on waveform data of the downstream pressure and waveform data of the two discharge pressures.

[0048] <Operation of the hydraulic circuit system> In the hydraulic circuit system 1A, the control device 14A outputs a first control signal according to a program or the like. This causes the first directional control valve 34 to operate. As a result, hydraulic fluid is supplied from the first hydraulic pump 11 to the hydraulic actuator 3 via the first fluid passage 21 and the junction passage 33. This causes the hydraulic actuator 3 to extend.

[0049] Furthermore, the control device 14 outputs a second control signal together with the first control signal according to a program or the like. This also operates the second directional control valve 34A. As a result, the hydraulic fluids from the two hydraulic pumps 11, 11A join together in the joining passage 33 and are then supplied to the hydraulic actuator 3. This allows a larger amount of hydraulic fluid to be supplied to the hydraulic actuator 3, enabling the hydraulic actuator 3 to extend more quickly.

[0050] <Fault diagnosis of hydraulic circuit systems> In the hydraulic circuit system 1A, the control device 14A determines whether there is an abnormality in the hydraulic circuit 12A based on the discharge pressure and the downstream pressure. More specifically, in the hydraulic circuit system 1A, the control device 14A determines whether there is an abnormality in the hydraulic circuit 12A based on the comparison result between the two discharge pressures and the downstream pressure. In this embodiment, the control device 14 determines whether there is an abnormality in the hydraulic circuit 12A based on the control signal, waveform data of the two discharge pressures, and waveform data of the downstream pressure. The abnormality diagnosis method will be described in more detail below.

[0051] In the hydraulic circuit system 1A, the control device 14A outputs first and second control signals. At this time, the control device 14A acquires the discharge pressure from each of the two upstream sensors 15, 15A, and acquires the downstream pressure from the downstream sensor 13. The control device 14A then generates waveform data of the discharge pressure from each of the two acquired discharge pressures, and generates waveform data of the downstream pressure from the acquired downstream pressure. The control device 14A compares the generated waveform data of the discharge pressure with the waveform data of the discharge pressure. The control device 14A diagnoses an abnormality in the hydraulic circuit 12 based on the comparison result.

[0052] For example, the waveform data of the two discharge pressures pulsates as shown in FIG. 5. In FIG. 5, the discharge pressure detected by the first upstream sensor 15 is the first waveform data, and the discharge pressure detected by the second upstream sensor 15A is the second waveform data. In this embodiment, the two hydraulic pumps 11, 11A have the same configuration, and therefore the discharge pressures fluctuate at essentially the same cycle. However, even for the two hydraulic pumps 11, 11A with the same configuration, slight differences in the waveform data occur due to slight individual differences in the configuration, etc. That is, the waveform data of the two discharge pressures have unique values ​​(see the dashed-two-dot circle 11a for the first waveform data and the dashed-dotted circle 11b for the second waveform data in FIG. 5). Furthermore, in the waveform data of the downstream pressure detected by the downstream sensor 13A, the unique values ​​of the waveform data of the two discharge pressures appear by detecting the hydraulic pressure after the merging (see the two circles 11a, 11b for the downstream pressure waveform data in FIG. 5). Therefore, the control device 14A can diagnose an abnormality in the hydraulic circuit 12A based on the comparison result between the first waveform data and the second waveform data and the downstream pressure waveform data. That is, the control device 14A compares whether two characteristic values ​​of the first waveform data and the second waveform data appear in the downstream pressure waveform data.

[0053] When two eigenvalues ​​appear in the downstream pressure waveform data as shown in FIG. 5, the hydraulic fluid from the two hydraulic pumps 11, 11A joins at the joining passage 33 and is supplied to the hydraulic actuator 3. Therefore, the control device 14 determines that the hydraulic circuit 12A is normal based on the presence or absence of two control signals being output, the first waveform data, the second waveform data, and the downstream pressure waveform data. On the other hand, as shown in FIG. 6, when two control signals are output but only one eigenvalue (e.g., the eigenvalue of the first waveform data) appears in the downstream pressure waveform data (see circle 11a in the downstream pressure waveform data in FIG. 6), it is determined that the hydraulic fluid from the second hydraulic pump 11A is not being guided to the joining passage 33. Therefore, the control device 14 determines that the hydraulic circuit 12A, more specifically, the second circuit system 31A, is abnormal based on the presence or absence of two control signals being output, the first waveform data, the second waveform data, and the downstream pressure waveform data.

[0054] In the hydraulic circuit system 1A of the second embodiment, it is possible to confirm whether the hydraulic fluid of each of the hydraulic pumps 11, 11A is being supplied to the downstream side of the hydraulic circuit 12A (hydraulic actuator 3 in this embodiment) based on the discharge pressure of each of the two hydraulic pumps 11, 11A and the downstream pressure detected by the downstream sensor 13A. This allows the control device 14 to determine whether the hydraulic fluids of either of the hydraulic pumps 11, 11A are not joining together in the hydraulic circuit 12A.

[0055] Furthermore, in the hydraulic circuit system 1A of the second embodiment, it is possible to check whether the hydraulic fluid discharged from the hydraulic pumps 11, 11A is being supplied to the downstream side of the hydraulic circuit 12A (hydraulic actuator 3 in this embodiment) via each circuit system 31, 31A based on the discharge pressures and downstream pressures of the plurality of hydraulic pumps 11, 11A, thereby making it possible to determine whether there is an abnormality in the circuit system 31, 31A.

[0056] Furthermore, in the hydraulic circuit system 1A of the second embodiment, waveform data relating to the discharge pressures of the multiple hydraulic pumps 11, 11A is taken into consideration when diagnosing abnormalities in each of the circuit systems 31, 31A. Diagnosis based on waveform data of the discharge pressure and the downstream pressure makes it easier to detect qualitative changes in the downstream pressure relative to the discharge pressure than diagnosis based solely on the discharge pressure and the downstream pressure. This makes it easier for the control device 14 to determine abnormalities in the hydraulic circuit 12. In other words, abnormality diagnosis of each of the circuit systems 31, 31A can be easily performed.

[0057] In addition, the hydraulic circuit system 1A has the same functions and effects as the hydraulic circuit system 1 of the first embodiment.

[0058] Third Embodiment 7, the hydraulic circuit system 1B of the third embodiment includes a plurality of hydraulic pumps 35, 35B, a hydraulic circuit 12A, a downstream sensor 13A, and a control device 14B. In this embodiment, the hydraulic circuit system 1B includes two hydraulic pumps 35, 35B.

[0059] Both the first hydraulic pump 35 and the second hydraulic pump 35B discharge hydraulic fluid. Both the first hydraulic pump 35 and the second hydraulic pump 35B are positive displacement, fixed displacement hydraulic pumps. In this embodiment, the hydraulic pumps 35, 35B are fixed displacement swash plate pumps. The hydraulic pumps 35, 35B have different discharge pressure pulsations. For example, the hydraulic pumps 35, 35B have different numbers of pistons, which results in different periods of the pulsations. Note that the hydraulic pumps 35, 35B may have different rotational phases of the pistons, which results in different rotational phases of the pulsations.

[0060] The control device 14B controls the movement of the directional control valves 34, 34A by outputting control signals in the same manner as the control device 14A. The control device 14B, which is an example of an abnormality diagnostic device, determines an abnormality in the hydraulic circuit 12A (more specifically, an abnormality in the circuit systems 31, 31A) based on the discharge pressures of the two hydraulic pumps 35, 35B and the downstream pressure detected by the downstream sensor 13A.

[0061] <Fault diagnosis of hydraulic circuit systems> In the hydraulic circuit system 1B, the control device 14B diagnoses an abnormality in the hydraulic circuit 12A based on the discharge pressure and the downstream pressure. More specifically, the control device 14B diagnoses an abnormality in each of the circuit systems 31, 31A based on the results of comparing the pulsation periods in each of the waveform data for the two discharge pressures with the pulsation periods included in the waveform data for the downstream pressure. The abnormality diagnosis method will be described in more detail below.

[0062] In the hydraulic circuit system 1B, the control device 14B operates the two directional control valves 34, 34A to open the two fluid passages 21, 21A. The control device 14B acquires the downstream pressure from the downstream sensor 13. The control device 14B generates downstream pressure waveform data from the acquired downstream pressure. The control device 14B also performs frequency analysis (e.g., FFT analysis) on the downstream pressure waveform data. The control device 14B acquires the intensity of each frequency related to the pulsation included in the downstream pressure waveform data. Furthermore, the control device 14B pre-stores the periods of the two discharge pressure pulsations. In the downstream pressure waveform data, the pulsations of the two working fluids appear superimposed due to the joining of the working fluids of the two hydraulic pumps 11, 11A. Therefore, in the analysis result (i.e., spectrum) obtained by frequency analyzing the downstream pressure waveform data, the energy intensity of the periods of the two discharge pressure pulsations is large. The control device 14 can diagnose abnormalities in the hydraulic circuit 12 based on a spectrum obtained by frequency analysis of the waveform data of the downstream pressure and a pulsation period stored in advance.

[0063] For example, when the two circuit systems 31 and 31A are normal, the spectrum of the waveform data of the downstream pressure has high energy intensities at two frequencies f1 and f2, as shown in Figure 8(a). On the other hand, when the second circuit system 31A is abnormal, the spectrum of the waveform data of the downstream pressure has low energy intensity at frequency f2, as shown in Figure 8(b). In this case, the control device 14B determines that the hydraulic circuit 12A is abnormal, and more specifically, that the second circuit system 31A is abnormal.

[0064] In the hydraulic circuit system 1B configured as above, the hydraulic pumps 35, 35B discharge hydraulic fluid that pulsates at different cycles. In this case, an abnormality in the hydraulic circuit 12A, more specifically, an abnormality in the circuit systems 31, 31A, can be diagnosed based on the cycles of the discharge pressure pulsation and the downstream pressure pulsation.

[0065] In addition, the hydraulic circuit system 1B has the same functions and effects as the hydraulic circuit system 1A of the second embodiment.

[0066] <Fourth embodiment> 9, the hydraulic circuit system 1C of the fourth embodiment includes a plurality of hydraulic pumps 11, 11A, a hydraulic circuit 12A, a signal generator 26, a downstream sensor 13A, a control device 14C, and upstream sensors 15, 15A. In this embodiment, the hydraulic circuit system 1C includes two hydraulic pumps 11, 11A. The hydraulic circuit system 1C also includes upstream sensors 15, 15A.

[0067] The signal generator 26 is provided in, for example, the second hydraulic pump 11A. The signal generator 26 may be provided in both of the two pumps 11, 11A. The signal generator 26 applies an additional signal to the hydraulic fluid by changing a first state quantity of the hydraulic fluid discharged from the second hydraulic pump 11A, i.e., the discharge pressure of the second hydraulic pump 11A. The signal generator 26 is, for example, an electromagnetic proportional control valve. The signal generator 26 is connected to the second fluid passage 21A of the hydraulic circuit 12A. The signal generator 26 may be a shutoff valve. If the signal generator 26 is a shutoff valve, it is interposed in the second fluid passage 21A. The signal generator 26 connects the second fluid passage 21A to the tank 25 in response to an input actuation signal. This changes the discharge pressure of the second hydraulic pump 11A, allowing the additional signal to be applied to the hydraulic fluid.

[0068] The control device 14C has the same functions as the control device 14A. Furthermore, the control device 14C further has the following functions: The control device 14C outputs an actuation signal. This allows the control device 14C to add an additional signal to the hydraulic fluid flowing through the second fluid passage 21A. For example, by outputting an actuation signal at a predetermined cycle, the control device 14C can cause hydraulic fluid having a pulsation with a different frequency component from the pulsation of the hydraulic fluid flowing through the first fluid passage 21A to flow through the second fluid passage 21A. In this way, the control device 14C adds an additional signal to the hydraulic fluid discharged from the second hydraulic pump 11A.

[0069] <Fault diagnosis of hydraulic circuit systems> In the hydraulic circuit system 1C, the control device 14C diagnoses an abnormality in the hydraulic circuit 12A based on the discharge pressure and the downstream pressure. More specifically, the control device 14C diagnoses an abnormality in each of the circuit systems 31, 31A in the same manner as the control device 14B. The abnormality diagnosis method will be described in more detail below.

[0070] In the hydraulic circuit system 1C, the control device 14C operates the two directional control valves 34, 34A to open the two fluid passages 21, 21A. Furthermore, the control device 14C operates the signal generator 26 by outputting an actuation signal. This causes an additional signal to be added to the hydraulic fluid flowing through the second fluid passage 21A. The control device 14C then generates waveform data for two discharge pressures from the two discharge pressures acquired from the upstream sensors 15, 15A. The control device 14C also generates waveform data for a downstream pressure from the downstream pressure acquired from the downstream sensor 13. The control device 14C then performs frequency analysis (e.g., FFT analysis) on the waveform data for the two discharge pressures and the waveform data for the downstream pressure (i.e., three waveform data). The control device 14C then compares the spectrum of the waveform data for the two discharge pressures with the spectrum of the waveform data for the downstream pressure.

[0071] Because the waveform data for the two discharge pressures have different frequency components, the control device 14 determines whether the waveform data for the downstream pressure contains the different frequency components. If the waveform data for the downstream pressure contains the different frequency components, the control device 14C determines that the hydraulic fluid from each hydraulic pump 11, 11A is being supplied to the hydraulic actuator 3 via each circuit system 31, 31A. Therefore, the control device 14C determines that the hydraulic circuit 12A is normal. On the other hand, if the waveform data for the downstream pressure contains the different frequency components, the control device 14C determines that the hydraulic fluid with the frequency components not included is not being supplied to the hydraulic actuator 3. Therefore, the control device 14C determines that the circuit system 31, 31A through which the hydraulic fluid with the frequency components not included flows is abnormal. In this way, the control device 14C can diagnose an abnormality in the hydraulic circuit 12A by comparing the results of the frequency analysis.

[0072] In the hydraulic circuit system 1C of the fourth embodiment, an additional signal is added to the hydraulic fluid by the signal generator 26. Therefore, by detecting the additional signal, it is possible to confirm whether the hydraulic fluid discharged from each hydraulic pump 11, 11A is being supplied to the downstream side of the hydraulic circuit 12A (hydraulic actuator 3 in this embodiment) via each circuit system 31, 31A.

[0073] In addition, the hydraulic circuit system 1C has the same functions and effects as the hydraulic circuit system 1B of the third embodiment.

[0074] Fifth Embodiment As shown in FIG. 10, a hydraulic circuit system 1D of the fifth embodiment includes a hydraulic pump 41, a hydraulic circuit 12D, a plurality of sensors 42 to 45, and a control device 14D. The hydraulic pump 41 is a positive displacement hydraulic pump that can discharge hydraulic fluid from either of two ports 41a, 41b. In this embodiment, the hydraulic pump 41 is a bi-rotating swash plate pump. For example, the hydraulic pump 41 is connected to an electric motor 46. When the hydraulic pump 41 is rotated in the forward direction by the electric motor 46, it discharges hydraulic fluid from one port 41a, and when the hydraulic pump 41 is rotated in the reverse direction, it discharges hydraulic fluid from the other port 41b.

[0075] <Hydraulic circuit> The hydraulic circuit 12D is connected to a hydraulic pump 41. The hydraulic circuit 12D includes a hydraulic actuator 3D. In the hydraulic circuit 12D, hydraulic fluid discharged from the hydraulic pump 41 is supplied to the hydraulic actuator 3D, thereby operating the hydraulic actuator 3D. In this embodiment, the hydraulic actuator 3D is a bidirectional hydraulic motor. However, the hydraulic actuator 3D may also be a hydraulic cylinder. The hydraulic circuit 12D also includes two pump passages 47L, 47R, two on-off valves 48L, 48R, and a supply / discharge mechanism 49.

[0076] The pump passages 47L and 47R are connected to the ports 41a and 41b of the hydraulic pump 41, respectively. The two pump passages 47L and 47R are also connected to the ports 41a and 41b of the hydraulic actuator 3D, respectively. Furthermore, throttles 47La and 47Ra are respectively interposed in the two pump passages 47L and 47R.

[0077] The on-off valves 48L, 48R are respectively provided in the pump passages 47L, 47R. More specifically, the on-off valves 48L, 48R are respectively provided in the pump passages 47L, 47R on the hydraulic actuator 3D side of the throttles 47La, 47Ra. The on-off valves 48L, 48R open and close the pump passages 47L, 47R in response to input control signals.

[0078] The supply / discharge mechanism 49 is connected to each of the pump passages 47L, 47R. The supply / discharge mechanism 49 supplies the pump passages 47L, 47R with hydraulic fluid when there is a shortage of hydraulic fluid during supply, etc. The supply / discharge mechanism 49 also discharges the hydraulic fluid into the tank 25 when the hydraulic pressure in each of the pump passages 47L, 47R exceeds a predetermined pressure.

[0079] <Sensor> The plurality of sensors 42-45 detect the hydraulic pressure of the hydraulic fluid flowing through each of the pump passages 47L, 47R. In this embodiment, four sensors 42-45 are provided in the hydraulic circuit system 1D. Each of the sensors 42-45 is connected to each of the pump passages 47L, 47R. More specifically, two sensors 42, 43 are connected to the first pump passage 47L. The two sensors 42, 43 are arranged on both sides of the throttle 47La in the first pump passage 47L. The two sensors 44, 45 are connected to the second pump passage 47R. The two sensors 44, 45 are arranged on both sides of the throttle 47Ra in the second pump passage 47R. Any of the plurality of sensors 42-45 detects the discharge pressure, which is a first state quantity, of the hydraulic fluid discharged from the hydraulic pump 41. Further, one of the plurality of sensors 42 to 45 detects the suction pressure, which is a second state quantity of the hydraulic fluid flowing downstream of the hydraulic circuit 12D.

[0080] More specifically, of the four sensors 42-43, when hydraulic fluid is discharged from one port 41a of the hydraulic pump 41, at least sensor 42 functions as an upstream sensor, and at least sensor 44 functions as a downstream sensor. That is, sensor 42 detects the discharge pressure, which is a first state quantity, of the hydraulic fluid discharged from the hydraulic pump 41, and sensor 44 detects the suction pressure, which is a second state quantity of the hydraulic fluid flowing downstream of the hydraulic circuit 12D. On the other hand, when hydraulic fluid is discharged from the other port 41b of the hydraulic pump 41, at least sensor 44 functions as an upstream sensor, and at least sensor 42 functions as a downstream sensor. That is, sensor 44 detects the discharge pressure, and sensor 42 detects the suction pressure.

[0081] <Control device> The control device 14D outputs control signals to the on-off valves 48L, 48R. The control device 14 opens and closes the pump passages 47L, 47R by outputting control signals to the on-off valves 48L, 48R. The control device 14D also controls the operation of the electric motor 46. More specifically, the control device 14D controls the rotation direction and rotation speed of the electric motor 46. This allows the control device 14D to control the discharge direction and discharge flow rate of the hydraulic pump 41.

[0082] Furthermore, the control device 14D, which is an example of an abnormality diagnosis device, determines whether there is an abnormality in the hydraulic circuit 12D based on the discharge pressure and suction pressure of the hydraulic pump 41. More specifically, the control device 14D acquires the discharge pressure and suction pressure using sensors 42, 44. The control device 14D determines whether there is an abnormality in the hydraulic circuit 12D based on the comparison result of the discharge pressure and the suction pressure.

[0083] <Operation of the hydraulic circuit system> In the hydraulic circuit system 1D, when no control signal is output from the control device 14D to the on-off valves 48L, 48R (i.e., referred to as the "de-energized state"), the pump passages 47L, 47R are open. In the de-energized state, the control device 14D drives the electric motor 46 to discharge hydraulic fluid from the hydraulic pump 41. This causes hydraulic fluid to be supplied to the hydraulic actuator 3D, and the hydraulic actuator 3D is activated. On the other hand, when the control device 14D outputs a control signal to the on-off valves 48L, 48R or stops driving the electric motor 46, the supply of hydraulic fluid from the hydraulic pump 41 to the hydraulic actuator 3D is stopped. This causes the operation of the hydraulic actuator 3D to be stopped.

[0084] <Fault diagnosis of hydraulic circuit systems> In the hydraulic circuit system 1D, the control device 14D diagnoses an abnormality in the hydraulic circuit 12D based on the discharge pressure and the suction pressure. More specifically, the control device 14D diagnoses an abnormality in the hydraulic circuit 12D based on the comparison result between the discharge pressure and the suction pressure. In this embodiment, the control device 14D diagnoses an abnormality in the hydraulic circuit 12D based on a first differential pressure, which is the differential pressure of the hydraulic pressures detected by the two sensors 42, 43, and a second differential pressure, which is the differential pressure of the hydraulic pressures detected by the two sensors 44, 45. The abnormality diagnosis method will be described in further detail below.

[0085] In the hydraulic circuit system 1D, the control device 14D acquires the pressures across the orifices 47La and 47Ra of the pump passages 47L and 47R from the four sensors 42-45 while the hydraulic pump 41 is de-energized and running. Based on the acquired pressures, the control device 14D calculates a first differential pressure, which is the differential pressure across the orifice 47La, and a second differential pressure, which is the differential pressure across the orifice 47Ra. The control device 14D then compares the first differential pressure with the second differential pressure. The first differential pressure and the second differential pressure correspond to the flow rates of fluid flowing into and out of the hydraulic circuit system 1D. Based on the comparison results, the control device 14D can diagnose an abnormality in the hydraulic circuit 12D, more specifically, a fluid leak. For example, if the absolute value of the difference between the first differential pressure and the second differential pressure is less than a predetermined value, no significant fluid leak is occurring in the on-off valves 48L and 48R, the hydraulic actuator 3D, or the supply / discharge mechanism 49 of the hydraulic circuit 12D. Therefore, the control device 14D diagnoses that there is no abnormality in the hydraulic pressure circuit 12D. On the other hand, if the absolute value of the difference between the first differential pressure and the second differential pressure is equal to or greater than a predetermined value, the flow rate out of the hydraulic pressure circuit 12D is small compared to the flow rate inflowing into the hydraulic pressure circuit 12D. Therefore, the control device 14D diagnoses that there is a large fluid leak in the hydraulic pressure circuit 12D, i.e., that there is an abnormality in the hydraulic pressure circuit 12D.

[0086] The hydraulic circuit system 1D of the fifth embodiment is a closed circuit, but has the same effects as the other open circuit hydraulic circuit systems 1 to 1C.

[0087] Sixth Embodiment As shown in Fig. 11, a hydraulic circuit system 1E of the sixth embodiment is provided in a steering device 2. The steering device 2 is a device for steering a vessel. The steering device 2 includes a steering gear 51 and a hydraulic circuit system 1E.

[0088] <Steering gear> The steering gear 51 is operated by receiving a supply of hydraulic fluid. When the steering gear 51 is operated, it changes the direction of the ship. The steering gear 51 includes a hydraulic actuator 52, a tiller 53, a rudder stock 54, and a rudder blade 55. The hydraulic actuator 52 is, for example, a ram cylinder, and has a ram 52a and a pair of cylinders 52b, 52c. The ram 52a is a rod-shaped member. A pair of cylinders 52b, 52c are provided at both end portions of the ram 52a. A pin 52e is provided at the axial center portion of the ram 52a. The tiller 53 is fixed to the rudder stock 54 and engaged with the pin 52e. The rudder stock 54 can rotate around its center. That is, the tiller 53 can rotate around the central axis of the rudder stock 54. The rudder blade 55 is fixed to the tiller 53.

[0089] In the steering gear 51 configured as above, when hydraulic fluid is supplied to either the cylinder 52b or 52c of the hydraulic actuator 52, the ram 52a moves forward or backward in one axial direction or the other. This causes the rudder 53 to be pushed by the pin 52e. This causes the rudder 53 to rotate around the rudder stock 54. This changes the angle of the rudder blade 55, i.e., the rudder angle. In this way, the ship can be steered.

[0090] <Hydraulic circuit system> The hydraulic circuit system 1E operates the steering gear 51 by supplying hydraulic fluid to the steering gear 51. More specifically, the hydraulic circuit system 1E operates the rudder blade 55 by supplying hydraulic fluid to a hydraulic actuator 52. The hydraulic circuit system 1E includes, for example, a plurality of hydraulic pumps 11L, 11R, a hydraulic circuit 12E, a plurality of downstream sensors 56L, 57L, 56R, 57R, and a control device 14E. The hydraulic circuit system 1E also includes a plurality of upstream sensors 15L, 15R.

[0091] <Hydraulic pump> The plurality of hydraulic pumps 11L, 11R all discharge hydraulic fluid. In this embodiment, the hydraulic circuit system 1E is provided with two hydraulic pumps 11L, 11R. The two hydraulic pumps 11L, 11R are positive displacement hydraulic pumps, similar to the hydraulic pump 11 in the first embodiment. That is, the hydraulic fluid discharged from each of the two hydraulic pumps 11L, 11R has a pulsating hydraulic pressure. In this embodiment, the two hydraulic pumps 11L, 11R are also swash plate pumps. However, the two hydraulic pumps 11L, 11R are not limited to swash plate pumps.

[0092] <Hydraulic circuit> The hydraulic circuit 12E is connected to both the hydraulic pumps 11L and 11R. The hydraulic circuit 12A is connected to the hydraulic actuator 52. The hydraulic circuit 12E controls the flow of hydraulic fluid supplied from the hydraulic pumps 11L and 11R to the hydraulic actuator 52. More specifically, the hydraulic circuit 12E has a plurality of circuit systems 31L and 31R to provide redundancy in the supply of hydraulic fluid to the hydraulic actuator 52. In this embodiment, the hydraulic circuit 12E has two circuit systems 31L and 31R, the same number as the hydraulic pumps 11L and 11R.

[0093] Each of the two circuit systems 31L, 31R is connected to a corresponding one of the hydraulic pumps 11L, 11R. More specifically, the first circuit system 31L is connected to the first hydraulic pump 11L, and the second circuit system 31R is connected to the second hydraulic pump 11R. The two circuit systems 31L, 31R have the same configuration. Therefore, only the configuration of the first circuit system 31L will be described below. When the configuration of the second circuit system 31R is the same as that of the first circuit system 31L, the letter "L" in the reference numerals of the same configurations is replaced with "R" and the description thereof will be omitted.

[0094] The first circuit system 31L has two pump passages 61L and 62L, two supply and discharge passages 63L and 64L, a directional control valve 34L, and a supply and discharge mechanism 65L. The first pump passage 61L is connected to the suction port 11La of the first hydraulic pump 11L, and the second pump passage 62L is connected to the discharge port 11Lb of the first hydraulic pump 11L. A throttle 62La is interposed in the second pump passage 62L. The supply and discharge passages 63L and 64L are connected to the first cylinder 52b and the second cylinder 52c of the hydraulic actuator 52, respectively. The directional control valve 34L is connected to the two pump passages 61L and 62L and the two supply and discharge passages 63L and 64L. The directional control valve 34L switches the connection destinations of the four passages 61L to 64L. This switches the flow direction of the hydraulic fluid supplied from the first hydraulic pump 11L to the hydraulic actuator 52. That is, the directional control valve 34L can switch the supply destination of the hydraulic fluid from the first hydraulic pump 11L to either of the two cylinders 52b, 52c of the hydraulic actuator 52. The supply / discharge mechanism 65L is connected to the supply / discharge passages 63L, 64L. The supply / discharge mechanism 65L supplies the supply / discharge passages 63L, 64L with hydraulic fluid that is insufficient during supply, etc. Furthermore, the supply / discharge mechanism 65L discharges the hydraulic fluid into the tank 25 when the hydraulic pressure in the supply / discharge passages 63L, 64L exceeds a predetermined pressure.

[0095] <Upstream sensor> The upstream sensors 15L, 15R detect first state quantities of the hydraulic fluid discharged from the hydraulic pumps 11L, 11R, respectively. In this embodiment, the hydraulic circuit system 1A includes two upstream sensors 15L, 15R, the same number as the hydraulic pumps 11L, 11R. The upstream sensors 15L, 15R are connected to the second pump passages 62L, 62R of the circuit systems 31L, 31R, respectively. More specifically, the upstream sensors 15L, 15R are connected to the upstream sides of the orifices 62La, 62Ra in the second pump passage 62L. In this embodiment, the upstream sensors 15L, 15R are located at the most upstream side of the second pump passages 62L, 62R. In this embodiment, the upstream sensors 15L, 15R are hydraulic pressure sensors that detect the discharge pressures of the hydraulic pumps 11L, 11R, respectively.

[0096] <Downstream sensor> The downstream sensors 56L, 57L, 56R, and 57R detect second state quantities of the hydraulic fluid flowing downstream of the hydraulic circuit 12E. More specifically, the downstream sensors 56L and 57L detect state quantities of the hydraulic fluid flowing downstream of the first circuit system 31L. The downstream sensors 56R and 57R detect state quantities of the hydraulic fluid flowing downstream of the second circuit system 31R. In this embodiment, the downstream sensors 56L and 57L are connected to the supply and discharge passages 63L and 64L of the first circuit system 31L, respectively. The downstream sensors 56R and 57R are connected to the supply and discharge passages 63R and 64R of the second circuit system 31R, respectively. In this embodiment, the downstream sensors 56L, 57L, 56R, and 57R are pressure sensors that detect the hydraulic pressure of the hydraulic fluid flowing through the connected supply and discharge passages 63L, 64L, 63R, and 64R. As a result, the downstream sensors 56L, 57L, 56R, and 57R detect the hydraulic pressure of the hydraulic fluid downstream of the circuit systems 31L and 31R, i.e., the downstream pressure. The downstream sensors 56L, 57L, 56R, and 57R may be flow rate sensors.

[0097] <Control device> The control device 14E has a function similar to that of the control device 14A. That is, the control device 14E controls the operation of the directional control valves 34L, 34R by outputting a control signal. More specifically, the control device 14E outputs first and second control signals according to a program or the like. The directional control valve 34L is operated by outputting the first control signal, and the directional control valve 34R is operated by outputting the second control signal.

[0098] Furthermore, the control device 14E, which is an example of an abnormality diagnosis device, determines an abnormality in the hydraulic circuit 12E based on the discharge pressures of the first hydraulic pump 11L and the second hydraulic pump 11R and the downstream pressures detected by the downstream sensors 56L, 57L, 56R, and 57R. More specifically, the control device 14 acquires the downstream pressures from the downstream sensors 56L, 57L, 56R, and 57R, and also acquires the discharge pressures from the two upstream sensors 15L and 15R. The control device 14 then compares the acquired downstream pressure with the two discharge pressures, and determines an abnormality in the hydraulic circuit 12E based on the comparison results. In this embodiment, the control device 14 determines an abnormality in the hydraulic circuit 12E (more specifically, an abnormality in the circuit systems 31L and 31R) based on waveform data of the downstream pressure and waveform data of the two discharge pressures.

[0099] <Operation of the hydraulic circuit system> In the hydraulic circuit system 1E, the control device 14E outputs a first control signal and a second control signal according to a program or the like. This causes the first directional control valve 34L and the second directional control valve 34R to operate. Then, hydraulic fluid is supplied from the first hydraulic pump 11L to the hydraulic actuator 52 via the first pump passage 61L and the supply / discharge passage 63L (or the supply / discharge passage 64L). Hydraulic fluid is also supplied from the second hydraulic pump 11R to the hydraulic actuator 52 via the first pump passage 61R and the supply / discharge passage 63R (or the supply / discharge passage 64R). This moves the ram 52a, changing the rudder angle of the rudder blade 52d. Therefore, the direction of the ship can be changed by the steering gear 51.

[0100] <Fault diagnosis of hydraulic circuit systems> In the hydraulic circuit system 1E, the control device 14E diagnoses an abnormality in the hydraulic circuit 12E based on the discharge pressure and downstream pressure. More specifically, in the hydraulic circuit system 1E, the control device 14E diagnoses an abnormality in the hydraulic circuit 12E based on a comparison of the discharge pressure and downstream pressure in each of the circuit systems 31L, 31R. In this embodiment, the control device 14E diagnoses an abnormality in the hydraulic circuit 12E based on waveform data of the discharge pressure, waveform data of the downstream pressure, and a control signal in each of the circuit systems 31L, 31R. The abnormality diagnosis method will be described in more detail below.

[0101] In the hydraulic circuit system 1E, the control device 14E outputs first and second control signals. The control device 14E acquires the discharge pressures from the upstream sensors 15L and 15R, and acquires the downstream pressures of the circuit systems 31L and 31R from the downstream sensors 56L, 57L, 56R, and 57R. The control device 14E then generates waveform data of the discharge pressures from the two acquired discharge pressures, and generates waveform data of the downstream pressures from the acquired downstream pressures. The control device 14E compares the generated waveform data of the discharge pressures with the waveform data of the discharge pressures. The control device 14E diagnoses an abnormality in the hydraulic circuit 12 based on the comparison results.

[0102] For example, the control device 14E outputs first and second control signals, causing the two directional control valves 34L, 34R to connect the second pump passages 62L, 62R to the supply / discharge passages 63L, 63R, respectively. The control device 14E acquires the discharge pressures from the upstream sensors 15L, 15R. The control device 14E then generates waveform data of the discharge pressures based on the acquired discharge pressures. The control device 14E also acquires the downstream pressures of the circuit systems 31L, 31R from the downstream sensors 56L, 57L, 56R, 57R. The control device 14E then generates waveform data of the downstream pressures based on the acquired downstream pressures. More specifically, the control device 14E generates waveform data of the downstream pressures of the circuit systems 31L, 31R based on the hydraulic pressure of the hydraulic fluid flowing through the supply / discharge passages 63L, 64L, 63R, 64L connected to the second pump passages 62L, 62R. That is, the control device 14E selects the supply / discharge passages 63L, 64L, 63R, 64L from which hydraulic pressure should be acquired based on the output first and second control signals. Then, the control device 14E acquires the hydraulic pressure of the hydraulic fluid flowing through the selected supply / discharge passages 63L, 64L, 63R, 64L as the downstream pressure. The control device 14E diagnoses an abnormality in the first circuit system 31L based on a comparison result between waveform data of the discharge pressure of the first hydraulic pump 11L and waveform data of the downstream pressure of the first circuit system 31L. The control device 14E also diagnoses an abnormality in the second circuit system 31R based on a comparison result between waveform data of the discharge pressure of the second hydraulic pump 11R and waveform data of the downstream pressure of the second circuit system 31R.

[0103] For example, if the pulsation in the waveform data of the downstream pressure is barely attenuated relative to the pulsation in the waveform data of the discharge pressure, the control device 14E determines that the first circuit system 31L is normal. On the other hand, if the pulsation in the waveform data of the downstream pressure is attenuated relative to the pulsation in the waveform data of the discharge pressure, the control device 14E determines that there is a fluid leak in the first circuit system 31L. Furthermore, if the pulsation in the waveform data of the downstream pressure is not present relative to the pulsation in the waveform data of the discharge pressure, the control device 14E determines that there is an abnormality in the first circuit system 31L, in which hydraulic fluid cannot be supplied. Similarly, the control device 14E compares the waveform data of the discharge pressure of the second hydraulic pump 11R with the waveform data of the downstream pressure of the supply / discharge passage 63R, and diagnoses an abnormality in the second circuit system 31R based on the comparison result.

[0104] Furthermore, even in a non-energized state in which the control device 14E does not output the first and second control signals, the control device 14E similarly diagnoses an abnormality in the hydraulic circuit 12E based on the waveform data. An example of an abnormality diagnosis will be described below. When pulsation in the waveform data of the downstream pressure does not appear compared to pulsation in the waveform data of the discharge pressure, the control device 14E determines that the first circuit system 31L is normal. On the other hand, when pulsation in the waveform data of the downstream pressure appears compared to pulsation in the waveform data of the discharge pressure, the control device 14E determines that an abnormality exists in the first circuit system 31L, such as when the directional control valve 34L is stuck and cannot operate. Similarly, the control device 14E diagnoses an abnormality in the second circuit system 31R based on the comparison result between the waveform data of the discharge pressure of the second hydraulic pump 11R and the waveform data of the downstream pressure.

[0105] The hydraulic circuit system 1E of the sixth embodiment configured as described above can diagnose abnormalities in the hydraulic circuit 12E including the multiple circuit systems 31L, 31R in the steering device 2. Therefore, it is possible to realize the steering device 2 having the functions described above.

[0106] In addition, the hydraulic circuit system 1E has the same functions and effects as the hydraulic circuit system 1A of the second embodiment.

[0107] <Other embodiments> In the hydraulic circuit systems 1, 1A to 1E of the first to sixth embodiments, the downstream pressure and discharge pressure may be corrected when generating waveform data. For example, a throttle (e.g., a fixed throttle) is provided in the fluid passage 21, 21A. The viscosity of the hydraulic fluid is estimated by detecting the pressure before and after the throttle with a sensor. Then, the downstream pressure and discharge pressure are corrected based on the estimated viscosity, and then the waveform data is generated. In addition to viscosity, the downstream pressure and discharge pressure may also be corrected based on factors such as pressure loss in the piping. By correcting the downstream pressure and discharge pressure in this manner, the accuracy of diagnosing abnormalities in the hydraulic circuits 12, 12A, 12E can be improved.

[0108] In the hydraulic circuit systems 1, 1A to 1E of the first to sixth embodiments, the state quantity for diagnosing abnormalities in the hydraulic circuits 12, 12A, 12D, and 12E is the hydraulic pressure of the hydraulic fluid, but it may also be the flow rate of the hydraulic fluid. Furthermore, the flow rate of the hydraulic fluid does not necessarily have to be measured directly by a sensor, but may be estimated from the detected hydraulic pressure of the hydraulic fluid.

[0109] In the hydraulic circuit systems 1, 1A to 1E of the first to sixth embodiments, other hydraulic circuits and hydraulic control devices (e.g., valves, throttles, etc.) may be interposed or connected between the hydraulic circuits 12, 12A, 12D, 12E and the hydraulic actuators 3, 52. Furthermore, the hydraulic control devices are not limited to the shutoff valves 22, 23 and the directional control valves 34, 34A, 34L, 34R described above, but may be other valves, throttles, etc. Furthermore, the control devices 14, 14A, 14B, 14E may diagnose an abnormality in the hydraulic circuits 12, 12A, 12E based on a first state quantity (e.g., discharge pressure) that is preset by, for example, measuring it in advance. More specifically, the control devices 14, 14A, 14B, 14E may diagnose an abnormality in the hydraulic circuits 12, 12A, 12E by comparing preset waveform data of the discharge pressure with waveform data of the detected downstream pressure.

[0110] The hydraulic circuit systems 1A to 1C, 1E of the second to fourth and sixth embodiments may include three or more hydraulic pumps. In this case, the control device diagnoses an abnormality in the hydraulic circuit based on a plurality of first state quantities and a plurality of second state quantities. Also, the hydraulic circuits 12A, 12E may have three or more circuit systems. Furthermore, a plurality of circuit systems may be connected to one hydraulic pump.

[0111] Exemplary Embodiments A hydraulic circuit system according to a first aspect includes at least one positive displacement pump, a hydraulic circuit connected to the pump, a downstream sensor for detecting a state quantity of hydraulic fluid flowing downstream of the hydraulic circuit, and an abnormality diagnosis device for determining an abnormality in the hydraulic circuit based on a comparison result between a first state quantity of hydraulic fluid discharged from the pump and a second state quantity of hydraulic fluid detected by the downstream sensor. According to this aspect, a change in the state quantity of hydraulic fluid flowing through the hydraulic circuit can be detected based on the first state quantity of hydraulic fluid discharged from the pump and the second state quantity of hydraulic fluid detected by the downstream sensor. An abnormality in the hydraulic circuit can then be determined based on the change in hydraulic pressure.

[0112] In a second aspect, the hydraulic circuit system is the hydraulic circuit system of the first aspect, wherein the hydraulic circuit includes at least one hydraulic control device that controls the flow of hydraulic fluid from the pump. According to the above aspect, it is possible to determine an abnormality in the hydraulic control device included in the hydraulic circuit.

[0113] In a third aspect, the hydraulic circuit system of the second aspect further includes a control device that outputs a control signal to the hydraulic control device, and the abnormality diagnosis device determines an abnormality in the hydraulic control device based on a comparison result between the control signal output from the control device, a first state quantity, and a second state quantity. According to the above aspect, it is possible to determine an abnormality in the response of the hydraulic control device to the control signal.

[0114] In a fourth aspect, the hydraulic circuit system is the hydraulic circuit system of any one of the first to third aspects, wherein the abnormality diagnosis device determines an abnormality in the hydraulic circuit based on waveform data of a first state quantity and a second state quantity. According to the above aspect, a qualitative change in the downstream pressure relative to the discharge pressure is more easily detected when diagnosing based on the waveform data of the first state quantity and the waveform data of the second state quantity than when diagnosing based simply on the first state quantity and the second state quantity. Therefore, the control device can more easily determine an abnormality in the hydraulic circuit.

[0115] In a fifth aspect, the hydraulic circuit system of the first aspect includes a plurality of the pumps, wherein the hydraulic circuit combines hydraulic fluids discharged from the plurality of pumps, and the abnormality diagnosis device determines an abnormality in the hydraulic circuit based on a plurality of first state quantities of the hydraulic fluid discharged from the plurality of pumps and a second state quantity detected by the downstream sensor. According to the above aspect, it is possible to confirm whether the hydraulic fluid discharged from each pump is supplied to the downstream side of the hydraulic circuit based on the plurality of first state quantities of the hydraulic fluid discharged from the plurality of pumps and the second state quantity detected by the downstream sensor. This allows the abnormality diagnosis device to determine which pumps' hydraulic fluids are not combined in the hydraulic circuit.

[0116] In a sixth aspect, the hydraulic circuit system is the hydraulic circuit system of the fifth aspect, wherein the hydraulic circuit includes a plurality of circuit systems to which the plurality of pumps are respectively connected and a confluence passage that confluences hydraulic fluid flowing through the plurality of circuit systems, the downstream sensor detects a second state quantity of hydraulic fluid flowing downstream of the confluence passage, and the abnormality diagnosis device determines an abnormality in the circuit system based on a plurality of first state quantities of hydraulic fluid discharged from each of the plurality of pumps and the second state quantity detected by the downstream sensor. According to the above aspect, by comparing the plurality of first state quantities of hydraulic fluid discharged from each of the plurality of pumps with the second state quantity detected by the downstream sensor, it is possible to confirm whether hydraulic fluid discharged from each pump is being supplied to the downstream side of the hydraulic circuit via each circuit system. This makes it possible to diagnose and determine an abnormality in the circuit system.

[0117] In a seventh aspect, the hydraulic circuit system is the hydraulic circuit system of the sixth aspect, wherein the abnormality diagnosis device determines an abnormality in the hydraulic circuit based on waveform data relating to a plurality of first state quantities of hydraulic fluid discharged from each of the plurality of pumps. According to the above aspect, the waveform data relating to a plurality of first state quantities of hydraulic fluid discharged from each of the plurality of pumps is taken into consideration. This makes it possible to easily diagnose an abnormality in each circuit system.

[0118] In an eighth aspect, the hydraulic circuit system of the sixth aspect further includes a signal generator provided in at least one of the plurality of pumps for changing a first state quantity of hydraulic fluid discharged from the pump to add an additional signal to the hydraulic fluid, and the abnormality diagnosis device determines an abnormality in the circuit system based on the first state quantity to which the additional signal has been added. According to the above aspect, by detecting the additional signal, it is possible to confirm whether the hydraulic fluid discharged from each pump has reached the downstream side of the hydraulic circuit via each circuit system.

[0119] In a ninth aspect, the hydraulic circuit system of any one of the first to eighth aspects further includes an upstream sensor that detects a first state quantity of hydraulic fluid discharged from the pump, and the abnormality diagnosis device determines an abnormality in the hydraulic circuit based on the first state quantity detected by the upstream sensor and a second state quantity of hydraulic fluid detected by the downstream sensor. According to the above aspect, the control device determines an abnormality in the hydraulic circuit based on actual state quantities upstream and downstream of the hydraulic circuit. Therefore, the control device can improve the accuracy in determining an abnormality in the hydraulic circuit.

[0120] A steering device includes the hydraulic circuit system with an abnormality diagnosis function according to any one of the first to ninth aspects. According to the above aspects, a steering device having the above-described functions can be realized. [Explanation of symbols]

[0121] 1,1A~1E Hydraulic circuit system 2 Steering gear 11, 11A, 11L, 11R hydraulic pump 12, 12A, 12D, 12E Hydraulic circuit 13, 13A, 56L, 56R, 57L, 57R Downstream sensor 14, 14A to 14E Control device (abnormality diagnosis device) 15, 15A, 15L, 15R Upstream sensor 22 First shutoff valve (hydraulic control equipment) 23 Second shutoff valve (hydraulic control equipment) 26 Signal Generator 31,31L 1st circuit system 31A,31R 2nd circuit system 33 Merging Passage 42~45 Sensor

Claims

1. A plurality of positive displacement pumps; a hydraulic circuit including a plurality of circuit systems to which the plurality of pumps are respectively connected, and a confluence passage that confluences hydraulic fluids flowing through the plurality of circuit systems; a downstream sensor that detects a state quantity of the hydraulic fluid flowing downstream of the junction passage; an abnormality diagnosis device that determines an abnormality in the hydraulic circuit based on a comparison result between a plurality of first state quantities of the hydraulic fluid discharged from each of the plurality of pumps and a second state quantity that is a state quantity of the hydraulic fluid detected by the downstream sensor; a signal generator provided in at least one of the plurality of pumps, the signal generator changing a first state quantity of the hydraulic fluid discharged from the pump to add an additional signal to the hydraulic fluid; The abnormality diagnosis device determines whether there is an abnormality in the circuit system based on the first state quantity to which the additional signal is added.

2. 2. The hydraulic circuit system with an abnormality diagnosis function according to claim 1, wherein the abnormality diagnosis device determines whether the hydraulic circuit has an abnormality based on waveform data of a first state quantity and a second state quantity.

3. 2. The hydraulic circuit system with an abnormality diagnosis function according to claim 1, wherein the abnormality diagnosis device determines an abnormality in the hydraulic circuit based on waveform data relating to a plurality of first state quantities of the hydraulic fluid discharged from each of the plurality of pumps.

4. an upstream sensor for detecting a first state quantity of the hydraulic fluid discharged from the pump; 2. The hydraulic circuit system with an abnormality diagnosis function according to claim 1, wherein the abnormality diagnosis device determines an abnormality in the hydraulic circuit based on a first state quantity detected by the upstream sensor and a second state quantity of the hydraulic fluid detected by the downstream sensor.

5. A steering device comprising the hydraulic circuit system with an abnormality diagnosis function according to any one of claims 1 to 4.

Images