Hydraulic System

Abstract

To provide a fluid pressure system which can determine whether or not a cylinder block is a conforming product.SOLUTION: A fluid pressure system includes: a fluid pressure device having a casing, a cylinder block having multiple first detected parts and at least one second detected part on an outer peripheral surface of a cylinder block body, a piston, an interlock mechanism, and a sensor which is provided at a position corresponding to the first detected parts and the second detected parts and respectively outputs a first signal and a second signal when the first detected part and the second detected part pass therethrough during rotation of the cylinder block; and a determination device which determines whether or not the cylinder block is a conforming product based on an output result output from the sensor. The first detected parts are formed spaced apart from each other by a predetermined first distance in a circumferential direction on the outer peripheral surface of the cylinder block body. The at least one second detected part is formed spaced apart from the adjacent first detected parts by a second distance different from the first distance on the outer peripheral surface of the cylinder block body.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a hydraulic system including a hydraulic device having a cylinder block in which a plurality of cylinder chambers are formed. [Background technology]

[0002] Known hydraulic devices include an axial pump and an axial motor, as described in Patent Document 1. Both the axial pump and the axial motor include a cylinder block. The cylinder block of the axial pump and the axial motor is replaced depending on the frequency of use, cumulative time, etc. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-212522 Summary of the Invention [Problem to be solved by the invention]

[0004] When replacing a cylinder block, it is necessary to use a cylinder block that is compatible with the hydraulic system, a so-called compatible product (e.g., a genuine product). However, there are also non-compatible cylinder blocks that are manufactured to be compatible for installation. If a non-compatible product is used in a hydraulic system, problems may occur, such as the hydraulic system not being able to achieve the desired function. Therefore, there is a need to be able to determine whether the cylinder block being used is a compatible product or a non-compatible product.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a hydraulic system that can determine whether a cylinder block is suitable for use. [Means for solving the problem]

[0006] a hydraulic system including a casing, a cylinder block rotatably supported by the casing and having a cylinder block body with a plurality of cylinder chambers formed around a rotation axis, the cylinder block body having a plurality of first detectable portions and at least one second detectable portion on its outer peripheral surface; pistons reciprocally accommodated in each of the cylinder chambers of the cylinder block; a linkage mechanism for reciprocating the pistons in conjunction with the rotation of the cylinder block; sensors provided at positions corresponding to the first detectable portions and the second detectable portions and outputting a first signal and a second signal when the first detectable portions and the second detectable portions pass by as the cylinder block rotates; and a determination device for determining whether the cylinder block is a conforming product based on the output results output by the sensor, wherein the plurality of first detectable portions are formed on the outer peripheral surface of the cylinder block body at a predetermined first interval in the circumferential direction, and the at least one second detectable portion is formed on the outer peripheral surface of the cylinder block body at a second interval different from the first interval from adjacent first detectable portions.

[0007] According to the first aspect of the present invention, by detecting the first and second detection portions as the cylinder block rotates, a first signal is output at a time interval corresponding to the first interval, and a second signal is output at a time interval corresponding to the second interval. By using the first and second signals output at different time intervals, the determination device can determine whether the cylinder block is a conforming product.

[0008] The hydraulic system of the second invention comprises a hydraulic device including: a casing; a cylinder block main body rotatably supported by the casing and having a plurality of cylinder chambers formed around a rotation axis; a cylinder block having N-1 first detectable portions formed on the outer surface of the cylinder block main body; pistons reciprocally accommodated in each of the plurality of cylinder chambers of the cylinder block; a linkage mechanism for reciprocating the pistons in conjunction with the rotation of the cylinder block; sensors provided at positions corresponding to the first detectable portions and outputting first signals when the first detectable portions pass by as the cylinder block rotates; and a determination device for determining whether the cylinder block is a conforming product based on the output results output from the sensors, wherein the first detectable portions are respectively located at any N-1 positions among N equal positions obtained by dividing the outer surface of the cylinder block main body into N equal parts.

[0009] According to the second aspect of the present invention, since there are no first detectable portions at the remaining position, when the first detectable portions are detected as the cylinder block rotates, the following occurs: The time interval between first signals output from two first detectable portions that are adjacent in the rotational direction to the remaining position differs from the time interval between first signals detected elsewhere. By varying the time intervals at which the first signals are output in this way, the determination device can determine whether the cylinder block is a conforming product.

[0010] A hydraulic system according to a third aspect of the present invention includes a cylinder block having a casing, a cylinder block body rotatably supported by the casing and having a plurality of cylinder chambers formed around a rotation axis, N-2 first detectable parts formed on the outer peripheral surface of the cylinder block body, and second detectable parts formed on the outer peripheral surface of the cylinder block body, pistons reciprocally accommodated in the plurality of cylinder chambers of the cylinder block, respectively, an interlocking mechanism that reciprocates the pistons in conjunction with the rotation of the cylinder block, and a mechanism that interlocks the first detectable parts and the second detectable parts. and a determining device that determines whether the cylinder block is a conforming product based on the output results output from the sensor, wherein the first detectable portions are disposed at any of N-2 positions among N equal positions on the outer peripheral surface of the cylinder block main body, and the second detectable portion is disposed at a position shifted from the remaining two of the N equal positions.

[0011] According to the third aspect of the present invention, since the second detection target is located at a position shifted from the remaining position, when the first detection target and the second detection target are detected as the cylinder block rotates, the time intervals at which the first signal and the second signal are output can be made different, and therefore, by using the first signal and the second signal, it can be determined whether the cylinder block is a conforming product. [Effects of the Invention]

[0012] According to the first to third aspects of the present invention, it is possible to determine whether or not a cylinder block is a conforming product. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view showing a hydraulic system according to first to fourth embodiments of the present invention. [Figure 2]2 is a cross-sectional view showing a cylinder block of a hydraulic device provided in the hydraulic system of FIG. 1, taken along line II-II. [Figure 3] 2 is a front view showing a cylinder block of a hydraulic device provided in the hydraulic system of FIG. 1. [Figure 4] 2 is a graph showing output results from sensors in the hydraulic system of FIG. 1. [Figure 5] FIG. 2 is a block diagram of a control device provided in the hydraulic system of FIG. [Figure 6] 5 is a graph showing the analysis results when the output results of FIG. 4 are subjected to FFT calculation processing. [Figure 7] FIG. 6 is a cross-sectional view showing a cylinder block provided in a hydraulic system according to a second embodiment of the present invention. [Figure 8] 8 is a graph showing the analysis results when the output results of the hydraulic system using the cylinder block of FIG. 7 are subjected to FFT calculation processing. [Figure 9] FIG. 10 is a cross-sectional view showing a cylinder block provided in a hydraulic system according to a third embodiment of the present invention. [Figure 10] 10 is a graph showing the analysis results when the output results of the hydraulic system employing the cylinder block of FIG. 9 are subjected to FFT calculation processing. [Figure 11] FIG. 10 is a cross-sectional view showing a cylinder block provided in a hydraulic system according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, hydraulic systems 1, 1A to 1C according to first to fourth embodiments of the present invention will be described with reference to the drawings. Note that the concepts of directions used in the following description are used for convenience of explanation and do not limit the orientation of the configuration of the invention to those directions. Furthermore, the hydraulic systems 1, 1A to 1C 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.

[0015] [First embodiment] <Hydraulic system> 1 is provided in various machines, such as construction machines such as excavators and cranes, industrial machines such as forklifts, agricultural machines such as tractors, and hydraulic machines such as presses. The hydraulic system 1 supplies hydraulic fluid to actuators provided in the various devices, or operates by receiving the hydraulic fluid. The hydraulic system 1 includes a hydraulic device 2 and a control device 3.

[0016] <Hydraulic equipment> The hydraulic device 2 functions as at least one of a hydraulic pump and a hydraulic motor. In this embodiment, the hydraulic device 2 is a hydraulic pump and a variable displacement swash plate pump. The hydraulic device 2 includes a casing 10, a cylinder block 11, a plurality of pistons 12, a swash plate 13, a regulator 14, a valve plate 15, and a sensor 16. The hydraulic device 2 may be a fixed displacement swash plate pump or a bent axis pump. The hydraulic device 2 can discharge hydraulic fluid by being driven by a drive source (for example, an engine E, an electric motor, or both; in this embodiment, the engine E).

[0017] <Casing> The casing 10 accommodates a cylinder block 11 and other components. An opening 10a is formed in one axial end of the casing 10, along which a predetermined axis L1 extends. An intake passage 10b and a discharge passage 10c are formed in the other axial end of the casing 10.

[0018] <Cylinder block> The cylinder block 11 includes a cylinder block main body 21, a plurality of first detectable portions 22, and a plurality of second detectable portions 23. The cylinder block main body 21 is housed in the casing 10. The cylinder block main body 21 is formed in a roughly cylindrical shape. A rotary shaft 24 is inserted through the cylinder block main body 21 along its axis so as not to rotate relative to the cylinder block main body 21. The rotary shaft 24 is supported by the casing 10 so as to be rotatable about the axis L1. That is, the cylinder block main body 21 is rotatably supported by the casing 10 via the rotary shaft 24. One end of the rotary shaft 24 protrudes from the opening 10a. One end of the rotary shaft 24 is connected to the engine E. When the engine E rotates the rotary shaft 24, the cylinder block 11 rotates about the axis L1.

[0019] The cylinder block body 21 also has a plurality of cylinder chambers 21a formed around the rotation shaft 24. More specifically, the cylinder block body 21 has a plurality of cylinder chambers 21a formed in its end face on one axial side. The cylinder chambers 21a extend to the other axial side. The cylinder chambers 21a open at the end face on the other axial side via cylinder ports 21b. In this embodiment, nine cylinder chambers 21a are formed in the cylinder block body 21. However, the number of cylinder blocks 11 described above is merely an example, and the number may be eight or less, or ten or more.

[0020] As shown in FIG. 2, the plurality of first detectable portions 22 are formed on the outer peripheral surface of the cylinder block main body 21. The plurality of first detectable portions 22 are spaced apart from one another in the circumferential direction on the outer peripheral surface of the cylinder block main body 21 at a first interval α (e.g., angle). More specifically, the first detectable portions 22 are formed at equal intervals on the outer peripheral surface of the cylinder block main body 21. In this embodiment, nine first detectable portions 22 are formed, the same number as the number of cylinder chambers 21a. That is, the nine first detectable portions 22 are formed on the outer peripheral surface of the cylinder block main body 21 at intervals of 40 degrees (=α) from one another about the axis L1. The number of first detectable portions 22 is not limited to being the same, and may be greater or less than that.

[0021] The first detectable portion 22 is a recess. However, as described below, the first detectable portion 22 may be a protrusion. More specifically, the first detectable portion 22 is a recessed groove. In this embodiment, the first detectable portion 22 is a groove having a depth extending radially inward and formed with a U-shaped cross section. However, the first detectable portion 22 is not limited to a U-shaped cross section, and may be a V-shaped, rectangular, or semicircular cross section, and any other shape is possible. The first detectable portion 22 is formed, for example, on the outer peripheral surface of the cylinder block main body 21, in the axial middle portion. The position where the first detectable portion 22 is formed is not limited to the above-described position. That is, the first detectable portion 22 may be formed on either one or the other axial side, or may be formed across the cylinder block main body 21 from one axial side to the other axial side.

[0022] The plurality of second detectable portions 23 are formed on the outer peripheral surface of the cylinder block main body 21. The plurality of second detectable portions 23 are spaced apart from adjacent first detectable portions 22 at a second interval β in the circumferential direction. The second interval β is an angle different from the first interval α. More specifically, the number of second detectable portions 23 formed on the outer peripheral surface of the cylinder block main body 21 is less than the number of first detectable portions 22. Each second detectable portion 23 is located between two adjacent first detectable portions 22. Each second detectable portion 23 is spaced apart from at least one of the two first detectable portions 22 at the second interval β. In this embodiment, three second detectable portions 23 are formed. The three second detectable portions 23 are spaced apart at equal intervals (for example, γ = 120 degrees apart from each other about the axis L1). Furthermore, the second detectable portions 23 are arranged at a second distance β from both of the two adjacent first detectable portions 22. The number of second detectable portions 23 may be one or two, or may be four or more. The multiple second detectable portions 23 do not necessarily have to be spaced at equal intervals. The second detectable portion 23 may also be arranged at the second distance β from only one of the two adjacent first detectable portions 22.

[0023] 3, the second detectable portions 23 are arranged together with the first detectable portions 22 on a partial circumferential surface b1 that extends in the circumferential direction on the outer circumferential surface of the cylinder block main body 21. That is, the second detectable portions 23 are arranged so as to overlap at least partially in the circumferential direction with the other second detectable portions 23 and all of the first detectable portions 22. In this embodiment, the first detectable portions 22 and the second detectable portions 23 are arranged so as to overlap entirely with each other in the circumferential direction.

[0024] Furthermore, the second detectable portion 23 is a recessed groove, similar to the first detectable portion 22. That is, in this embodiment, the second detectable portion 23 is a groove having a depth extending radially inward and having a U-shaped cross section. Note that the second detectable portion 23 is also not limited to a U-shaped cross section, and may have a V-shaped, rectangular, or semicircular cross section, and any other shape is possible. Furthermore, the second detectable portion 23 is formed, for example, on the outer peripheral surface of the cylinder block main body 21, in the axial middle portion. Note that the position where the second detectable portion 23 is formed is not limited to the above-described position. That is, the second detectable portion 23 may be formed on either one or the other axial side, or may be formed across the cylinder block main body 21 from one axial side to the other axial side.

[0025] <Piston> The plurality of pistons 12 are inserted into the respective cylinder chambers 21a of the cylinder block 11. Each of the pistons 12 reciprocates in its respective cylinder chamber 21a. A shoe 26 is attached to the tip of each piston 12 so as to be slidable and rotatable.

[0026] <Swash plate> The swash plate 13, an example of an interlocking mechanism, is spaced from one axial side of the cylinder block 11 and tilted toward the cylinder block 11. The swash plate 13 supports shoes 26 from one axial side. More specifically, the swash plate 13 is provided with a shoe plate 27. The shoe plate 27 supports the shoes 26. The shoe plate 27 is also provided with a retaining plate 28. The retaining plate 28 presses the shoes 26 against the shoe plate 27. The shoes 26 rotate around the axis L1 on the tilted shoe plate 27 while being pressed by the retaining plate 28. Therefore, when the cylinder block 11 rotates, the pistons 12 reciprocate within the cylinder chamber 21a. The swash plate 13 can change its tilt angle by rotating around an axis L2 perpendicular to the axis L1. This allows the stroke of the pistons 12 to be adjusted. As will be described later, the discharge amount from the hydraulic device 2 can be changed.

[0027] <Regulator> The regulator 14 can change the tilt angle of the swash plate 13 by rotating the swash plate 13 about the axis L2 of the swash plate 13. More specifically, the regulator 14 has a servo piston (not shown) connected to the swash plate 13 via a connecting member 14a. The regulator 14 moves the servo piston in response to an input signal. More specifically, the signal input to the regulator 14 is a pilot pressure. The pilot pressure is regulated by a solenoid valve 25. The regulator 14 adjusts the tilt angle of the swash plate 13 in response to the regulated pilot pressure.

[0028] <Valve plate> The valve plate 15 is interposed between the other axial end face of the casing 10 and the cylinder block 11. The valve plate 15 is formed with an intake port 15a and a discharge port 15b, which are connected to the intake passage 10b and the discharge passage 10c, respectively. The intake port 15a and the discharge port 15b switch between connected cylinder ports 21b as the cylinder block 11 rotates. The intake port 15a guides working fluid from the intake passage 10b to the cylinder chamber 21a via the connected cylinder port 21b. The discharge port 15b discharges working fluid from the cylinder chamber 21a to the discharge passage 10c via the connected cylinder port 21b.

[0029] <Sensor> The sensor 16 is provided at a position corresponding to the first and second detection targets 22 and 23. When the first and second detection targets 22 and 23 pass by the sensor 16 as the cylinder block 11 rotates, the sensor 16 outputs a first signal S1 and a second signal S2, respectively (see FIG. 4). More specifically, the sensor 16 is provided on the casing 10 at a position corresponding to the partial circumferential surface b1 of the cylinder block 11 (in this embodiment, a position radially opposite the partial circumferential surface b1). The sensor 16 is, for example, an electromagnetic pulse generator. That is, the sensor 16 outputs a first signal S1 and a second signal S2 when the detection targets 22 and 23 pass in front of the sensor 16 (detection position). Therefore, the output result of the sensor 16 (i.e., change in output over time) corresponds to the shape of the outer circumferential surface of the cylinder block main body 21. The sensor 16 may be an MRE rotation sensor or an optical rotation sensor.

[0030] <Operation of hydraulic device> In the hydraulic device 2, the engine E drives the rotary shaft 24, causing the cylinder block 11 to rotate about the axis L1. This causes the multiple pistons 12 to rotate about the axis L1 and reciprocate in the cylinder chamber 21a. Furthermore, as the cylinder block 11 rotates, the connection destination of the cylinder port 21b switches between the suction port 15a and the discharge port 15b. As a result, hydraulic fluid is sucked into the cylinder chamber 21a via the suction port 15a, and the hydraulic fluid is discharged from the cylinder chamber 21a to the discharge port 15b. In this way, the hydraulic device 2 discharges hydraulic fluid.

[0031] In the hydraulic device 2, when a pilot pressure is input to the regulator 14, the swash plate 13 tilts in accordance with the pilot pressure. More specifically, by adjusting the pilot pressure with the solenoid valve 25, the tilt angle of the swash plate 13 can be adjusted via the regulator 14. This adjusts the stroke of the pistons 12. Therefore, the discharge volume of the hydraulic device 2 can be adjusted.

[0032] <Control device> The control device 3 controls the operation of the hydraulic device 2. More specifically, the control device 3 controls the operation of the regulator 14. That is, the control device 3 controls the operation of the solenoid valve 25. This adjusts the pilot pressure output from the solenoid valve 25, thereby controlling the tilt angle of the swash plate 13. The control device 3, which is an example of a determination device, includes an LPF unit 31, an FFT calculation processing unit 32, a rotation speed conversion unit 33, a control unit 34, and a notification unit 35, as shown in FIG. 5 . The control device 3 determines whether the cylinder block 11 is a conforming product based on the output result from the sensor 16. More specifically, the control device 3 performs FFT calculation on the output result from the sensor 16 to perform spectral analysis on the output result. The control device 3 then determines whether the cylinder block 11 is a conforming product based on the result of the FFT calculation. The control device 3, which is an example of a limiting device, limits the output of the hydraulic device 2 based on the determination result. In this embodiment, the control device 3 limits the maximum output of the hydraulic device 2. However, the control device 3 may be configured to reduce the overall output when the cylinder block 11 is determined to be non-conforming compared to when the cylinder block 11 is determined to be conforming. Furthermore, the control device 3, which is an example of an informing device, notifies the user whether the cylinder block 11 is conforming or not, depending on the determination result.

[0033] The LPF unit 31 removes high frequency components from the output result output from the sensor 16. In other words, the LPF unit 31 is a low-pass filter. The FFT calculation processing unit 32 performs FFT calculation processing on the output result filtered by the LPF unit 31. More specifically, the FFT calculation processing unit 32 converts the sensor output output from the sensor 16 into frequency components by performing spectrum analysis on the output result (see FIG. 6).

[0034] The rotation speed conversion unit 33 calculates the rotation speed of the cylinder block 11 per unit time. More specifically, the rotation speed conversion unit 33 calculates the rotation speed based on the reference component in the analysis result of the FFT operation processing unit 32. In the present embodiment, the first detection units 22 are formed at equal intervals in the hydraulic device 2. Therefore, the first signal S1 is output at a time interval t1 (rotation speed / number of cylinder bores in the present embodiment) corresponding to the rotation speed of the cylinder block 11. And since more first detection units 22 are formed than the second detection units 23, more first signals S1 are output. Then, in the analysis result, the frequency component caused by the first signal S1, that is, the spectrum of the first frequency component f1 (reference component) appears with the strongest signal intensity. Therefore, the rotation speed conversion unit 33 calculates the rotation speed based on the first frequency component f1 which is the reference component.

[0035] Also, the rotation speed conversion unit 33 calculates an identification component according to the rotation speed. The identification component is a frequency component for comparison with the analysis result when determining whether the cylinder block 11 is a conforming product. More specifically, in the hydraulic device 2, when the cylinder block 11 is rotated, the second signal S2 is output after the time interval t2 has elapsed after the immediately preceding first signal S1 is output as shown in FIG. 4. And the second signal S2 is output at a time interval t2 (<t1) different from the time interval t1 of the first signal S1. Also, the first signal S1 is output at the time interval t2 after the second signal S2. Thereby, in the analysis result, a second frequency component f2 different from the first frequency component f1 appears (see FIG. 6). The second frequency component f2 is a value corresponding to the second interval β of the second detection unit 23 and the rotation speed. Therefore, when the identification component is set to a value that can be calculated by the coefficient corresponding to the second interval β of the second detection unit 23 and the rotation speed, it is possible to determine whether the second detection unit 23 is formed at the second interval β by comparing the identification component with the second frequency component f2. That is, it is possible to determine whether the cylinder block 11 is a conforming product by comparing the identification component with the second frequency component f2. Therefore, the rotation speed conversion unit 33 calculates the identification component based on the calculated rotation speed and the second interval β.

[0036] The control unit 34 determines whether the cylinder block 11 is a conforming product based on the analysis results of the FFT calculation processing unit 32 and the discrimination component of the rotation speed conversion unit 33. More specifically, the control unit 34 selects frequencies with strong signal strength from the analysis results. In this embodiment, the spectrum of the second frequency component f2 is selected from the analysis results in addition to the spectrum of the first frequency component f1. The control unit 34 then compares the second frequency component f2 with the discrimination component to determine whether the cylinder block 11 is a conforming product. That is, if the second frequency component f2 is identical to the discrimination component or within a predetermined range (e.g., a tolerance or detection error range), the control unit 34 determines that the cylinder block 11 is a conforming product. On the other hand, if the second frequency component f2 is not within a predetermined range for the discrimination component, the control unit 34 determines that the cylinder block 11 is a non-conforming product.

[0037] Furthermore, if the control unit 34 determines that the cylinder block 11 is non-conforming, it limits the output of the hydraulic device 2. In this embodiment, the control unit 34 limits the maximum output of the hydraulic device 2. More specifically, the control unit 34 controls the operation of the solenoid valve 25 to limit the maximum tilt point angle of the swash plate 13 to less than a predetermined angle. This reduces the maximum discharge rate of the hydraulic device 2, thereby reducing the maximum output of the hydraulic device 2. The control unit 34 also controls the operation of the engine E. The control unit 34 may limit the output of the hydraulic device 2 by reducing the output of the engine E. The control unit 34 may also delay the tilt response of the swash plate 13 in a ramp-like manner.

[0038] The notification unit 35 notifies the user whether the cylinder block 11 is a conforming product or not based on the determination result. More specifically, the notification unit 35 notifies the user whether the cylinder block 11 is a conforming product or not by, for example, sounding, displaying, or emitting light. The notification unit 35 also transmits information regarding whether the cylinder block 11 is a conforming product or not to a predetermined data center or the like.

[0039] <Hydraulic system evaluation> In the hydraulic system 1, when the cylinder block 11 rotates, the sensor 16 outputs a first signal S1 and a second signal S2, the number of which corresponds to the number of detected parts 22, 23. In the control device 3, the LPF unit 31 removes high-frequency components from the output result of the sensor 16. The FFT calculation processing unit 32 then performs spectrum analysis on the output result filtered by the LPF unit 31. The rotation speed conversion unit 33 calculates the rotation speed and the identification component based on the analysis result. The control unit 34 then compares the calculated identification component with the second frequency component f2 to determine whether the cylinder block 11 is a conforming product.

[0040] If the control unit 34 determines that the cylinder block 11 is a conforming product, the control unit 34 permits the maximum output. That is, the control unit 34 allows the maximum tilt angle of the swash plate 13 in the hydraulic device 2 to be equal to or greater than a predetermined angle. The permitted tilt angle (i.e., the predetermined angle) may be set according to the pressure. On the other hand, if the control unit 34 determines that the cylinder block 11 is a non-conforming product, the control unit 34 limits the maximum output. For example, the control unit 34 controls the regulator 14 to limit the output of the hydraulic device 2. More specifically, the control unit 34 controls the regulator 14 to limit the maximum tilt angle of the swash plate 13 in the hydraulic device 2 to less than the predetermined angle. As a result, the maximum output of the hydraulic device 2 is limited when the cylinder block 11 is a non-conforming product.

[0041] Furthermore, the control unit 34 transmits information regarding whether or not the cylinder block 11 is a conforming product to a predetermined data center or the like by the notification unit 35. The notification unit 35 also notifies the user or the like whether or not the cylinder block 11 is a conforming product by sound, display, or light emission.

[0042] According to the hydraulic system 1 of this embodiment, the first detectable portion 22 and the second detectable portion 23 are each detected as the cylinder block 11 rotates. This results in a first signal S1 being output at a time interval t1 corresponding to the first interval α and a second signal S2 being output at a time interval t2 corresponding to the second interval β (see FIG. 4). Then, by using the first signal S1 and the second signal S2 output at different time intervals, the control device 3 can determine whether the cylinder block 11 is a conforming product.

[0043] In this embodiment, the sensor 16 outputs a first signal S1 at equal time intervals t1 based on the first detectable portion 22. Therefore, the first signal S1 is used as a reference signal. On the other hand, after the sensor 16 outputs the immediately preceding first signal S1, it outputs a second signal S2 at time intervals t2 based on the second detectable portion 23. The second signal S2 is then output at time intervals t2 that are different from the time intervals of the first signal S1 and correspond to the second interval β. Therefore, the second signal S2 is used as an identification signal. Using the first signal S1 and the second signal S2, the time interval t2 at which the second signal S2 is output (the second frequency component f2 in this embodiment) is compared with a predetermined time interval (the identification component in this embodiment). This allows the control device 3 to determine whether the cylinder block 11 is a qualified product.

[0044] Furthermore, the hydraulic system 1 performs FFT calculations to perform spectrum analysis on the output results from the sensor 16. This makes it possible to easily determine the time interval t2 at which the second signal S2 is output, i.e., the difference in the second interval β, by using the spectrum of each frequency in the analysis results. This makes it possible to easily and accurately determine whether the cylinder block 11 is a suitable product.

[0045] Furthermore, according to the hydraulic system 1, by limiting the output of the hydraulic device 2 based on the judgment result, it is possible to suppress the occurrence of malfunctions in the hydraulic device 2 that uses a non-conforming cylinder block 11. Furthermore, according to the hydraulic system 1, since the hydraulic device 2 is a variable displacement swash plate type hydraulic device, it is possible to easily limit the output of the hydraulic device 2.

[0046] More specifically, the use of a compliant cylinder block 11 in the hydraulic system 2 ensures high responsiveness of the hydraulic system 2 to the current in terms of the discharge flow rate and tilt angle. Therefore, more precise and sophisticated control of the discharge flow rate of the hydraulic system 2 can be performed while also taking horsepower control into consideration. As a result, the hydraulic system 2 can be controlled to achieve high operational performance and good fuel economy. On the other hand, if a non-compliant cylinder block is used in the hydraulic system 2, performance in terms of the discharge flow rate and tilt angle responsiveness cannot be ensured. Therefore, performing control similar to that performed when a compliant cylinder block 11 is used would actually result in a decrease in at least one of fuel economy and operational performance. In particular, the decrease in tilt angle responsiveness is significant. For example, when the hydraulic system 1 is applied to an excavator, a decrease in tilt angle responsiveness affects the likelihood of hunting occurring in response to the operator's operation. Therefore, to prevent such problems from occurring, the control device 3 executes the following control when a non-compliant cylinder block is used in the hydraulic system 2. That is, the control device 3 reduces the maximum output of the hydraulic device 2 or reduces the responsiveness of the tilt angle. This prevents a significant decrease in at least one of the driving performance and fuel economy of the hydraulic device 2, even if a non-conforming cylinder block is used in the hydraulic device 2.

[0047] Furthermore, according to the hydraulic system 1, the control device 3 can notify the user, manager, etc. whether the cylinder block 11 is a conforming product. This notifies the driver that, instead of the optimal control that would be performed if a conforming product were used, appropriate control must be performed in the hydraulic device 2 in which the non-conforming cylinder block 11 is used.

[0048] Furthermore, according to the hydraulic system 1, the first detection target portion 22 and the second detection target portion 23 are each a recess, so that the first detection target portion 22 and the second detection target portion 23 can be easily and accurately formed. This makes it possible to accurately determine whether the cylinder block 11 is a conforming product.

[0049] Furthermore, according to the hydraulic system 1, the second detectable portions 23 are also formed regularly (i.e., with a spacing γ between the second detectable portions 23) in the same manner as the first detectable portions 22, so that the weight balance of the cylinder block main body 21 can be made more even.

[0050] Furthermore, according to the hydraulic system 1, the first detectable portion 22 and the second detectable portion 23 are arranged side by side on the partial circumferential surface b1. Therefore, the sensor 16 that detects the first detectable portion 22 and the second detectable portion 23 can be shared, thereby reducing the number of parts.

[0051] Furthermore, according to the hydraulic system 1, a pulse generator is used for the sensor 16, so that the first detectable portion 22 and the second detectable portion 23, which are the detection targets, can be prevented from having a complex configuration.

[0052] [Second embodiment] The hydraulic system 1A of the second embodiment is similar in configuration to the hydraulic system 1 of the first embodiment (see FIG. 1). More specifically, the hydraulic system 1A of the second embodiment differs from the hydraulic system 1 of the first embodiment in that the hydraulic device 2 has a cylinder block 11A shown in FIG. 7. Therefore, the cylinder block 11A will be mainly described below. Furthermore, when other components of the hydraulic system 1A of the second embodiment are the same as those of the hydraulic system 1 of the first embodiment, the same reference numerals are used and descriptions thereof will be omitted. The same applies to the cylinder block 11A.

[0053] The cylinder block 11A in the second embodiment includes a cylinder block main body 21 and a plurality of first detectable portions 22A. The plurality of first detectable portions 22A are respectively formed on the outer peripheral surface of the cylinder block main body 21. More specifically, N-1 first detectable portions 22A are formed on the cylinder block main body 21. In this embodiment, N is 9. That is, eight first detectable portions 22A are formed on the cylinder block main body 21. The first detectable portions 22A are respectively arranged at N-1 positions, excluding one remaining position 30, among positions obtained by dividing the outer peripheral surface of the cylinder block main body 21 into N equal parts. In this embodiment, the first detectable portions 22A are respectively arranged at eight positions, from the first to the eighth, among positions obtained by dividing the outer peripheral surface of the cylinder block main body 21 into nine equal parts. Furthermore, the first detectable portion 22A and other detectable portions are not formed at the ninth remaining position 30. The first detected portion 22A is then detected by the sensor 16. The sensor 16 outputs a first signal S1 in response to the first detected portion 22A.

[0054] In the hydraulic system 1A of the second embodiment configured as described above, the first detection parts 22A are arranged at equal intervals from the first to eighth positions of nine equal divisions on the outer peripheral surface of the cylinder block main body 21. Therefore, when the cylinder block 11A rotates, the first signal S1 is output from the sensor 16 at time intervals t1 corresponding to the rotation speed of the cylinder block 11 from the first to eighth positions.

[0055] On the other hand, the first detection target 22A is not present at the ninth remaining position 30. Therefore, for example, the first signal S1 is not output from the sensor 16 after the eighth position passes by until the first position passes by the sensor 16 again. That is, the first signal S1 is output from the sensor 16 at a time interval t0 (= t1 × 2) that is different from the time interval t1 during that time. As a result, the analysis results show a frequency component f0 (= (f1) / 2) that is different from the first frequency component f1 resulting from the time interval t1, as shown in FIG. 8. The control unit 34 determines whether the cylinder block 11A is a conforming product by comparing the frequency component f0 with a previously calculated discrimination component.

[0056] In the hydraulic system 1A of the second embodiment configured as described above, the first detectable portion 22A is not located at the remaining position 30. Therefore, when the first detectable portion 22A is detected as the cylinder block 11A rotates, the following occurs: The time interval t0 of the first signal S1 output from the first detectable portion 22A located adjacent to the remaining position 30 in the rotational direction differs from the time interval t1 of the first signal S1 detected elsewhere. By varying the time intervals at which the first signal S1 is output in this manner, the control device 3 can determine whether the cylinder block 11A is a conforming product.

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

[0058] [Third embodiment] The hydraulic system 1B of the third embodiment is similar in configuration to the hydraulic system 1A of the second embodiment (see FIG. 1). More specifically, the hydraulic system 1B of the third embodiment differs from the hydraulic system 1A of the second embodiment in that the hydraulic device 2 has a cylinder block 11B shown in FIG. 9. Therefore, the cylinder block 11B will be mainly described below. Regarding other components of the hydraulic system 1B of the third embodiment, if they are identical to those of the hydraulic system 1A of the second embodiment (i.e., the hydraulic system 1 of the first embodiment), the same reference numerals will be used and descriptions thereof will be omitted. The same applies to the cylinder block 11B.

[0059] The cylinder block 11B in the third embodiment includes a cylinder block main body 21, a plurality of first detectable portions 22A, and a plurality of second detectable portions 23B. Each of the second detectable portions 23B is formed on the outer peripheral surface of the cylinder block main body 21. The second detectable portions 23B are disposed offset from the Nth (ninth in this embodiment) remaining position 30. More specifically, the second detectable portions 23B are disposed offset from the remaining position 30 between the first and eighth positions. That is, the eight first detectable portions 22A are disposed on the outer peripheral surface of the cylinder block main body 21 at a first interval α (= 40 degrees). The second detectable portions 23B are disposed at a second interval β from the first detectable portion 22A disposed at the eighth position. The second detectable portions 23B are detected by the sensor 16. The sensor 16 outputs a second signal S2 in response to the second detected portion 23B.

[0060] In the cylinder block 11B of the third embodiment configured as described above, the second detection target 23B is positioned between the first position and the eighth position, offset from the remaining position 30. Therefore, when the cylinder block 11B rotates, the time interval t2 at which the second signal S2 is output differs from the time interval t1. Therefore, as shown in FIG. 10, the analysis result shows a second frequency component f2 that differs from the first frequency component f1 resulting from the time interval t1. Furthermore, because the second detection target 23B is positioned offset from the Nth position, the time interval t3 at which the first signal S1 is output after the second signal S2 is output differs from both the time intervals t1 and t2. Therefore, the analysis result also shows a third frequency component f3. The control unit 34 uses these three frequency components f1, f2, and f3 to determine whether the cylinder block 11B is a conforming product.

[0061] In the hydraulic system 1B of the third embodiment configured as described above, when the first detection target 22A and the second detection target 23B are detected as the cylinder block 11B rotates, the time intervals t1, t2, and t3 at which the first signal S1 and the second signal S2 are output can be made different. Therefore, by using the first signal S1 and the second signal S2, it can be determined whether the cylinder block 11B is a conforming product.

[0062] In addition, the hydraulic system 1B of the third embodiment has the same functions and effects as the hydraulic system 1A of the second embodiment.

[0063] [Fourth embodiment] The hydraulic system 1C of the fourth embodiment is similar in configuration to the hydraulic system 1B of the third embodiment (see FIG. 1). More specifically, the hydraulic system 1C of the fourth embodiment differs from the hydraulic system 1B of the third embodiment in that the hydraulic device 2 has a cylinder block 11C shown in FIG. 11. Therefore, the cylinder block 11C will be mainly described below. Furthermore, with regard to other components of the hydraulic system 1C of the fourth embodiment, if they are identical to the hydraulic system 1B of the third embodiment (i.e., if they are identical to the hydraulic system 1 of the first embodiment), the same reference numerals will be used and their description will be omitted. The same applies to the cylinder block 11C.

[0064] A cylinder block 11C of the fourth embodiment includes a cylinder block main body 21, a plurality of first detectable portions 22C, and a second detectable portion 23B. N-2 first detectable portions 22C are formed on the cylinder block main body 21. The first detectable portions 22C are respectively arranged at N-2 positions among N equal positions on the outer peripheral surface of the cylinder block main body 21. In this embodiment, N is 9. The first detectable portions 22C are respectively arranged at the first to seventh positions among N equal positions on the outer peripheral surface of the cylinder block main body 21. In other words, the first detectable portions 22C and other detectable portions are not formed at the eighth and ninth remaining positions 41, 42.

[0065] The second detection target portions 23B are formed on the outer peripheral surface of the cylinder block main body 21. The second detection target portions 23B are disposed offset from the Nth and N-1th (eighth and ninth in this embodiment) remaining positions 41, 42. More specifically, the second detection target portions 23B are disposed offset from the two remaining positions 41, 42 between the first position and the seventh position. That is, the seven first detection target portions 22C are disposed on the outer peripheral surface of the cylinder block main body 21 at a first interval α (= 40 degrees). The second detection target portions 23B are disposed at a third interval δ (≠α) from the first detection target portion 22C disposed at the seventh position.

[0066] In the cylinder block 11C of the fourth embodiment configured as described above, similar to the cylinder block 11B of the third embodiment, when the cylinder block 11C rotates, the time interval t4 at which the second signal S2 is output is different from the time interval t1. Furthermore, because the second detection target 23C is positioned offset from the Nth position, the first signal S1 is output at the time interval t5 after the second signal S2 is output. Therefore, the control unit 34 obtains three different frequency components f1, f4, and f5 in the analysis result, and can use the three frequency components f1, f4, and f5 to determine whether the cylinder block 11C is a conforming product.

[0067] In the hydraulic system 1C of the fourth embodiment configured as described above, when the first detection target 22C and the second detection target 23B are detected as the cylinder block 11C rotates, the time intervals t1, t4, and t5 at which the first signal S1 and the second signal S2 are output can be varied. Therefore, by using the first signal S1 and the second signal S2, it can be determined whether the cylinder block 11C is a conforming product.

[0068] In addition, the hydraulic system 1C of the fourth embodiment has the same effects as the hydraulic system 1B of the third embodiment.

[0069] [Other embodiments] In the hydraulic systems 1, 1A to 1C of this embodiment, the detection target portions 22, 22A, 22C, 23, and 23B are arranged at two different intervals on the outer circumferential surface of the cylinder block main body 21. The detection target portions 22, 22A, 22C, 23, and 23B may be arranged at three or more different intervals (for example, at three intervals relative to the target detection target portions). In this case, the analysis results show three or more frequency components with strong signal intensities, and if all of these frequency components are the same or within a predetermined range relative to the identification components, the cylinder block 11 is determined to be a conforming product. Furthermore, the first interval α does not necessarily have to be an interval that equally divides the outer circumferential surface of the cylinder block main body 21. In other words, if there are nine first detection target portions 22, the first interval α does not necessarily have to be 40 degrees, but may be less than 40 degrees or greater than 40 degrees. Furthermore, the detection target portions 22 and 23 are recessed grooves, but may also be protrusions (e.g., ridges).

[0070] Furthermore, in the hydraulic system 1 of the first embodiment, the second detectable portion 23 is disposed at the second distance β from both of the two adjacent first detectable portions 22, but the second detectable portion 23 does not necessarily have to be disposed in this manner. For example, the second detectable portion 23 may be disposed at a distance different from the first distance α and the second distance β from the other of the two adjacent first detectable portions 22 (the first detectable portion 22 on the other circumferential side). In this case, frequency components different from the first frequency component f1 and the second frequency component f2 appear in the analysis results. The control unit 34 then uses these three frequency components to determine whether the cylinder block 11 is a compliant product.

[0071] Furthermore, in the hydraulic systems 1, 1A to 1C of this embodiment, the detection target portions 22, 22A, 22C, 23, and 23B are recessed grooves, but they may be any other suitable material that the sensor 16, which is a pulse generator, reacts to. The detection target portions 22, 22A, 22C, 23, and 23B may be, for example, metal plates or reflecting plates that reflect the electromagnetic waves or light emitted by the sensor 16. Furthermore, the detection target portions 22, 22A, 22C, 23, and 23B do not necessarily need to be arranged side by side on the partial circumferential surface b1. For example, a sensor 16 may be provided for each detection target portion 22, 22A, 22C, 23, and 23B, and the output results from each sensor 16 may be combined.

[0072] Although the hydraulic device 2 of this embodiment has been described using a hydraulic pump device as an example, it may also be a hydraulic motor device as described above. When the hydraulic device 2 is a hydraulic motor device, the process is basically the same as when it is a hydraulic pump device. However, if the cylinder block 11, 11A to 11C is non-conforming, the control device 3 controls the tilt angle of the swash plate 13 to limit the torque of the rotating shaft 24 as the output of the hydraulic device 2. For example, the control device 3 may decrease the rotation speed by increasing the tilt angle of the swash plate 13. [Explanation of symbols]

[0073] 1,1A~1C Hydraulic system 2 Hydraulic device 3. Control device (judgment device, limiting device, alarm device) 10 Casing 11, 11A~11C Cylinder block 12 pistons 13 Swash plate 14 Regulator 16 sensors 21 Cylinder block body 21a Cylinder chamber 22,22A,22C 1st detected part 23,23B 2nd detected part 24 Rotation Axis S1 1st signal S2 2nd signal α First interval β 2nd interval

Claims

1. a cylinder block rotatably supported by the casing, the cylinder block body having a plurality of cylinder chambers formed around a rotation axis and having a plurality of first detectable portions and at least one second detectable portion on the outer peripheral surface thereof; pistons reciprocally accommodated in each of the plurality of cylinder chambers of the cylinder block; an interlocking mechanism for reciprocating the pistons in conjunction with the rotation of the cylinder block; and sensors provided at positions corresponding to the first detectable portions and the second detectable portions, and for outputting a first signal and a second signal when the first detectable portion and the second detectable portion pass by as the cylinder block rotates. and a determination device that determines whether the cylinder block is a suitable product based on the output result output from the sensor. The plurality of first detection portions are formed on the outer peripheral surface of the cylinder block body at predetermined first intervals in the circumferential direction, A hydraulic system, wherein the at least one second detectable portion is formed on the outer peripheral surface of the cylinder block body at a second interval in the circumferential direction from the adjacent first detectable portion, the second interval being different from the first interval.

2. 2. The hydraulic system according to claim 1, wherein the determination device performs an FFT process on the output result from the sensor and determines whether the cylinder block is a conforming product based on the result of the FFT process.

3. The hydraulic system according to claim 1 or 2, further comprising a limiting device that limits an output of the hydraulic device or reduces responsiveness based on a determination result of the determining device.

4. The hydraulic device further includes a regulator for changing the tilt angle of the swash plate, which is the interlocking mechanism. The hydraulic system according to claim 3 , wherein the limiting device controls the regulator to limit the output of the hydraulic device or reduce responsiveness.

5. 5. The hydraulic system according to claim 1, further comprising an informing device that informs whether the cylinder block is a conforming product or not based on the determination result of the determining device.

6. a hydraulic pressure device comprising: a casing; a cylinder block body rotatably supported by the casing and having a plurality of cylinder chambers formed around a rotation axis; a cylinder block having N-1 first detectable portions formed on the outer peripheral surface of the cylinder block body; pistons reciprocally accommodated in each of the plurality of cylinder chambers of the cylinder block; a linkage mechanism that reciprocates the pistons in linkage with the rotation of the cylinder block; and sensors provided at positions corresponding to the first detectable portions, and that output first signals when the first detectable portions pass by during rotation of the cylinder block; a determination device that determines whether the cylinder block is a conforming product based on the output result output from the sensor, A hydraulic system, wherein the first detection portions are respectively disposed at any (N-1) positions among N equal divisions of the outer peripheral surface of the cylinder block body.

7. a second detection portion formed on the outer peripheral surface of the cylinder block body; The hydraulic system according to claim 6 , wherein the second detected portion is disposed offset from the remaining position.

8. a cylinder block having N-2 first detectable portions formed on the outer peripheral surface of the cylinder block body and second detectable portions formed on the outer peripheral surface of the cylinder block body; pistons reciprocally accommodated in each of the cylinder chambers of the cylinder block; a linkage mechanism that reciprocates the pistons in conjunction with the rotation of the cylinder block; and sensors that are provided at positions corresponding to the first detectable portions and the second detectable portions and that output first and second signals when the first detectable portions and the second detectable portions pass by during rotation of the cylinder block. a determination device that determines whether the cylinder block is a conforming product based on the output result output from the sensor, the first detection portions are disposed at N-2 positions among N equal divisions of the outer peripheral surface of the cylinder block body, A hydraulic system, wherein the second detection part is disposed at a position shifted from the remaining two remaining positions among the N equally divided positions.

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