Hydraulic rotary machine

Abstract

To provide a radial piston-type hydraulic rotary machine capable of measuring the amount of eccentricity of a drum.SOLUTION: A hydraulic rotary machine 1 according to one embodiment includes a rotating shaft 2 extending along a rotation axis 20, a housing 5 including a plurality of cylinder bores 50 arranged radially around the rotation axis 20, and a drum 4 that rotates together with the rotating shaft 2 to reciprocate a plurality of pistons 61 disposed in the cylinder bores 50, respectively. The hydraulic rotary machine 1 further includes: an eccentricity adjustment mechanism 3 that varies the eccentricity of the drum 4, which is the distance from the rotation axis 20 to the center of the drum 4; a rotary encoder 84 that detects the rotational angle of the rotating shaft 2; and at least one linear encoder that detects the position of a specific circle concentric with the drum 4 on a straight line perpendicularly intersecting the rotation axis 20.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to radial piston hydrostatic rotary machines. [Background technology]

[0002] A radial piston hydraulic rotating machine has been known in the past, in which a plurality of cylinder bores are arranged radially around a rotating shaft, and a plurality of pistons respectively arranged in the plurality of cylinder bores reciprocate as a result of a rotation of a drum having a center at a position different from the rotating shaft. Such a hydraulic rotating machine may be a hydraulic pump or a hydraulic motor.

[0003] For example, Patent Document 1 discloses a variable displacement radial piston hydraulic pump. In this hydraulic pump, the eccentricity of the drum, which is the distance from the rotating shaft to the center of the drum, is changed by an eccentricity adjuster, thereby changing the capacity of the hydraulic pump. In Patent Document 1, the drum is called the "eccentric cam" and the eccentricity adjuster is called the "eccentricity change mechanism." [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-63447 Summary of the Invention [Problem to be solved by the invention]

[0005] However, there is a demand for highly accurate control of the displacement of variable displacement hydraulic rotary machines, which requires measuring the amount of eccentricity of the drum.

[0006] Therefore, an object of the present disclosure is to provide a radial piston type hydraulic rotating machine capable of measuring the amount of eccentricity of a drum. [Means for solving the problem]

[0007] The present disclosure provides a radial piston type hydraulic rotating machine comprising: a rotating shaft extending along a rotating axis; a housing including a plurality of cylinder bores arranged radially around the rotating axis; a drum that rotates together with the rotating shaft to reciprocate a plurality of pistons respectively disposed in the plurality of cylinder bores; an eccentricity adjuster that changes the eccentricity of the drum, which is the distance from the rotating axis to the center of the drum; a rotary encoder that detects the rotation angle of the rotating shaft; and at least one linear encoder that detects the position of a specific circle concentric with the drum on a straight line perpendicular to the rotating axis. Effect of the Invention

[0008] According to the present disclosure, there is provided a radial piston type hydraulic rotating machine capable of measuring the amount of eccentricity of a drum. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a front view of a hydraulic rotary machine according to an embodiment. [Diagram 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Diagram 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 2 is a cross-sectional view taken along line IV-IV in FIG. [Diagram 5] FIG. 2 is a perspective view of the drum and drum plate. [Figure 6] FIG. 6A is a perspective view of the carriage, and FIG. 6B is a perspective view of the guide. [Figure 7] 1 is a diagram showing the relationship between the radius Rd of a specific circle, the distance X, the eccentric angle θ, and the amount of eccentricity e. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 1 and 2 show a radial piston type hydraulic rotating machine 1 according to one embodiment. The hydraulic rotating machine 1 may be a hydraulic pump or a hydraulic motor. The hydraulic fluid used in the hydraulic rotating machine 1 is typically oil.

[0011] The hydraulic rotating machine 1 includes a rotating shaft 2 extending along a rotating axis 20, a housing 5 that rotatably supports the rotating shaft 2 via bearings 11 and 12, and an annular drum 4 arranged within the housing 5. For ease of explanation, the left side in Fig. 2, which is one side of the extending direction of the rotating shaft 20, will be referred to as the front, and the right side in Fig. 2, which is the opposite side, will be referred to as the rear.

[0012] 3, the housing 5 includes a plurality of cylinder bores 50 arranged radially around the rotation shaft 20. That is, the axial direction of each cylinder bore 50 is a radial direction centered on the rotation shaft 20. In this embodiment, the number of cylinder bores 50 is seven, but the number of cylinder bores 50 may be five or six, or eight or more.

[0013] In this embodiment, the housing 5 includes a housing main body 5A located around and behind the drum 4, a plurality of cylinder covers 5B attached to the housing main body 5A so as to cover the cylinder bores 50 from the radial outside centered on the rotating shaft 20, a front cover 5C located in front of the drum 4 and the housing main body 5A, a spacer 5D located behind the housing main body 5A, and a valve housing 5E located further behind the spacer 5D.

[0014] The rotating shaft 2 passes through the front cover 5C, the housing main body 5A, and the spacer 5D. A valve spool 72 is arranged coaxially behind the rotating shaft 2, and is connected to the rotating shaft 2 by a cross coupling 71. The valve spool 72 is accommodated in a valve housing 5E and slides relative to the valve housing 5E.

[0015] As shown in Fig. 3, the drum 4 has a center 40 at a position different from the rotating shaft 20. A plurality of pistons 61 are disposed in each cylinder bore 50. Each piston 61 is container-shaped and opens radially inward from the rotating shaft 20, and a connection rod 62 is connected to the piston 61 inside the piston 61. The drum 4 rotates together with the rotating shaft 2, causing the piston 61 to reciprocate via the connection rod 62.

[0016] In this embodiment, the connection rod 62 slides on the outer circumferential surface of the drum 4. Specifically, the connection rod 62 is maintained in contact with the outer circumferential surface of the drum 4 by a ring 64. A through hole is provided at the center of each piston 61, and a lubrication passage 63 is provided along the center line of each connection rod 62. Hydraulic fluid is supplied as a lubricant to the sliding surface between the connection rod 62 and the drum 4 through the through hole and the lubrication passage 63.

[0017] 2 and 3, the housing body 5A includes an annular portion 51 that surrounds the rotation space 13 of the drum 4, a bottom wall 53 that covers the rotation space 13 from the rear, and a plurality of boss portions 52 that protrude radially outward from the annular portion 51 about the rotation shaft 20. The boss portions 52 are cylindrical and form a cylinder bore 50 together with the annular portion 51.

[0018] The above-mentioned front cover 5C covers from the front the rotation space 13 of the drum 4. The above-mentioned bearings 11, 12 are held by the front cover 5C and the bottom wall 53 of the housing main body 5A, respectively.

[0019] The above-mentioned valve housing 5E is provided with a first port 1a and a second port 1b extending from the outer surface to the inner surface of the valve housing 5E. The inner surface of the valve housing 5E is the surface on which the valve spool 72 slides. When the hydraulic rotating machine 1 is a hydraulic pump, one of the first port 1a and the second port 1b is a suction port and the other is a discharge port, and when the hydraulic rotating machine 1 is a hydraulic motor, one of the first port 1a and the second port 1b is an inlet port and the other is an outlet port.

[0020] Further, the valve housing 5E, the spacer 5D and the housing main body 5A are provided with passages 5a, the number of which is the same as the number of cylinder bores 50, extending from the inner surface of the valve housing 5E to the cylinder bores 50.

[0021] Furthermore, the valve spool 72 is provided with passages 7a that connect some of the passages 5a to the first port 1a and passages 7b that connect some other of the passages 5a to the second port 1b depending on the rotational position of the valve spool 72.

[0022] The hydraulic rotating machine 1 further includes an eccentricity adjuster 3 that changes the eccentricity e of the drum 4, which is the distance from the rotating shaft 20 to the center 40 of the drum 4. In this embodiment, due to the arrangement of the eccentricity adjuster 3, the portion of the rotating shaft 2 located inside the drum 4 is substantially H-shaped as shown in FIG.

[0023] More specifically, a protrusion 22 is provided in a portion of the rotating shaft 2 located inside the drum 4, protruding from a cylindrical main body centered on the rotating shaft 20 in the eccentric direction of the drum 4, which is the direction from the rotating shaft 20 toward the center 40 of the drum 4. A first recess 23 that opens in the eccentric direction of the drum 4 is provided in the protrusion 22. Furthermore, a second recess 21 that opens in the opposite direction to the eccentric direction of the drum 4 is provided on the opposite side to the first recess 23 in a portion of the rotating shaft 2 located inside the drum 4.

[0024] The eccentric amount adjuster 3 includes a first eccentric piston 31 disposed in the first recess 23, a spring 32 disposed in a first pressure chamber 24 formed between the first eccentric piston 31 and the bottom of the first recess 23, which urges the first eccentric piston 31 in the eccentric direction of the drum 4, and a second eccentric piston 33 disposed in the second recess 21. A second pressure chamber 26 is formed between the second eccentric piston 33 and the bottom of the second recess 21.

[0025] The above-mentioned spacer 5D is provided with a first eccentric switching port 1c and a second eccentric switching port 1d so as to extend from the outer surface to the inner surface of the spacer 5D. In addition, the rotating shaft 2 is provided with a passage 25 that connects the first eccentric switching port 1c to the first pressure chamber 24, and a passage 27 that connects the second eccentric switching port 1d to the second pressure chamber 26. By changing the eccentric switching pressure introduced into the first pressure chamber 24 through the first eccentric switching port 1c and the passage 25, the position of the first eccentric piston 31 is changed, and thus the eccentric amount e of the drum 4 is adjusted, and the capacity of the hydraulic rotating machine 1 is changed.

[0026] When the capacity of the hydraulic rotating machine 1 is switched from large to small capacity, the eccentric switching pressure is introduced into the second pressure chamber 26 through the second eccentric switching port 1d and the passage 27 while keeping the eccentric switching pressure introduced into the first pressure chamber 24. Since the area of ​​the second pressure chamber 26 is set larger than the area of ​​the first pressure chamber 24, even if the eccentric switching pressure introduced into the first pressure chamber 24 and the eccentric switching pressure introduced into the second pressure chamber 26 are equal, the introduction of the eccentric switching pressure into the second pressure chamber 26 causes the second eccentric piston 33 to advance and the first eccentric piston 31 to retreat.

[0027] Furthermore, in this embodiment, the hydraulic rotating machine 1 includes a rotary encoder 84 as shown in FIG. 2, and two linear encoders 9 as shown in FIG.

[0028] 2, a drive shaft 83 is coaxially attached to the above-mentioned valve spool 72, and a rotary encoder 84 detects the rotation angle of the rotating shaft 2 at the tip of the drive shaft 83. The rotary encoder 84 is housed in a rotary encoder casing 82, and the rotary encoder casing 82 is fixed to the above-mentioned valve housing 5E via a spacer 81.

[0029] The two linear encoders 9 detect the position of a specific circle 14 concentric with the drum 4, as shown in Fig. 5. As shown in Fig. 1, one linear encoder 9 detects the position of the specific circle 14 on a straight line 9a that perpendicularly intersects with the rotation shaft 20, and the other linear encoder 9 detects the position of the specific circle 14 on a straight line 9b that perpendicularly intersects with the rotation shaft 20. In other words, the two linear encoders 9 are spaced apart from each other in the circumferential direction centered on the rotation shaft 20.

[0030] The two linear encoders 9 are attached to the annular portion 51 between the boss portions 52 of the housing main body 5A. In other words, the two linear encoders 9 are disposed within a region in which the boss portions 52 exist in the extension direction of the rotating shaft 20, and overlap with the boss portions 52 when viewed from the circumferential direction about the rotating shaft 20.

[0031] In this embodiment, the angle between the straight lines 9a, 9b is 72 degrees. If the angle between the straight lines 9a, 9b is 72 degrees in this manner, it is possible to attach two linear encoders 9 to the annular portion 51 between the boss portions 52, whether the number of boss portions 52 is seven as in this embodiment or five as in another embodiment. However, the angle between the straight lines 9a, 9b is not limited to 72 degrees and can be changed as appropriate.

[0032] As shown in Fig. 5, in this embodiment, a drum plate 45 is attached to the front surface of the drum 4 as an accessory to the drum 4, and an annular groove 46 is formed in the drum plate 45 along the specific circle 14 described above. In other words, the center line of the annular groove 46 is the specific circle 14. The drum plate 45 is fixed to the drum 4 by a plurality of bolts 47 as shown in Fig. 4.

[0033] 4, each linear encoder 9 includes a linear encoder cover 91, a linear encoder body 93, a rod 92, a carriage 94, a roller 95, and a guide 96. The annular portion 51 of the housing main body 5A is provided with through holes at positions where the linear encoders 9 are arranged, the through holes penetrating the annular portion 51 in the radial direction about the rotation shaft 20.

[0034] The linear encoder body 93 is fixed in a state inserted into the through hole provided in the annular portion 51 of the housing main body 5A. The rod 92 is supported by the linear encoder body 93 so as to be slidable in the radial direction centered on the rotation shaft 20. The linear encoder cover 91 is in the shape of a container that houses the portion of the rod 92 that protrudes outward from the linear encoder body 93, and is fixed to the annular portion 51 of the housing main body 5A.

[0035] The carriage 94 is attached to the tip of the rod 92, and the roller 95 is attached to the carriage 94 via a shaft. For example, a cam follower can be used as the roller 95 and the shaft. The roller 95 fits into the annular groove 46 of the drum plate 45.

[0036] More specifically, a fitting hole is provided on the tip surface of the rod 92. Meanwhile, as shown in Fig. 6A, the carriage 94 includes an L-shaped main body 94a that is aligned along the axial direction of the rod 92 and a direction perpendicular to the axial direction, and a cylindrical portion 94b that protrudes from the main body 94a toward the rod 92 and fits into the fitting hole. The main body 94a is also provided with a hole 94c that fits with the above-mentioned shaft that rotatably supports the roller 95.

[0037] The guide 96 guides the movement of the carriage 94 in the radial direction around the rotation shaft 20. As shown in Figs. 4 and 6B, the guide 96 includes, together with the linear encoder body 93, a disk portion 96a inserted into the through hole provided in the annular portion 51 of the housing main body 5A, and a column portion 96b protruding from the disk portion 96a toward the rotation shaft 20. A through hole 96c through which the rod 92 is inserted is provided in the center of the disk portion 96a, and a guide groove 96d into which the carriage 94 engages is provided in the column portion 96b. The movement of the carriage 94 is guided by the engagement of the carriage 94 into the guide groove 96d.

[0038] As described above, in the hydraulic rotating machine 1 of this embodiment, as shown in Fig. 7, the distance X between the rotating shaft 20 and the detected position of the specific circle 14 can be obtained from the position of the specific circle 14 detected by the linear encoder 9, and the eccentricity angle θ, which is the angle between the straight line 9a or 9b on which the linear encoder 9 performs position detection and the eccentricity direction of the drum 4, can be obtained from the rotation angle of the rotating shaft 2 detected by the rotary encoder 84. Then, by using the radius Rd of the specific circle in addition to the distance X and the eccentricity angle θ, the eccentricity amount e of the drum 4 can be calculated. Therefore, the eccentricity amount e of the drum 4 can be measured.

[0039] More specifically, the calculation of the eccentricity e of the drum 4 is carried out by applying the cosine theorem to a triangle having vertices at the position of the specific circle 14 on the straight line 9a or 9b, the rotation axis 20 and the center 40 of the drum 4, thereby deriving the following formula 1. Rd 2 =e 2 +X 2 -2eXcosθ (Formula 1)

[0040] Then, by transforming Equation 1, we obtain Equation 2. e 2 -2eXcosθ+(X 2 -Rd 2 )=0...(Formula 2)

[0041] By solving Equation 2 for e using the quadratic formula, the eccentricity e can be calculated. Note that one of the two solutions will be negative or an unrealistic value, so the other solution that is not such a value will be selected as the correct solution.

[0042] In addition, in this embodiment, the two linear encoders 9 are attached to the annular portion 51 between the boss portions 52 of the housing body 5A, so that the space between the boss portions 52 can be effectively used as an arrangement space for the linear encoders 9.

[0043] <Modification> The present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present disclosure.

[0044] For example, the connection rod 62 does not necessarily need to slide on the outer circumferential surface of the drum 4, and a bearing may be disposed between the connection rod 62 and the drum 4 as in the hydraulic pump of Patent Document 1.

[0045] Also, in the above embodiment, the number of linear encoders 9 is two, but the number of linear encoders may be one. However, when the number of linear encoders 9 is one, both of the solutions to the quadratic equation in Equation 2 may be inappropriate values ​​depending on the eccentricity angle θ of the drum 4. In contrast, when the number of linear encoders 9 is two as in the above embodiment, one of the four solutions will be an appropriate value regardless of the value of the eccentricity angle θ of the drum 4. Therefore, the eccentricity amount e of the drum can be calculated appropriately.

[0046] Furthermore, each linear encoder 9 does not have to include the guide 96. However, if each linear encoder 9 includes the guide 96 as in the above embodiment, the eccentricity e of the drum can be measured with high accuracy.

[0047] Also, the drum plate 45 may be omitted and the annular groove 46 may be formed on the front surface of the drum 4. Alternatively, the roller 95 of the linear encoder 9 may be pressed against the outer circumferential surface of the drum 4 by a spring and roll on the outer circumferential surface of the drum 4. In this case, the specific circle 14 is defined by the outer circumferential surface of the drum 4.

[0048] <Summary> In a first aspect, the present disclosure provides a radial piston type hydraulic rotating machine comprising: a rotating shaft extending along a rotating axis; a housing including a plurality of cylinder bores arranged radially around the rotating axis; a drum that rotates together with the rotating shaft to reciprocate a plurality of pistons respectively arranged in the plurality of cylinder bores; an eccentricity adjuster that changes the eccentricity of the drum, which is the distance from the rotating axis to the center of the drum; a rotary encoder that detects the rotation angle of the rotating shaft; and at least one linear encoder that detects the position of a specific circle concentric with the drum on a straight line perpendicular to the rotating axis.

[0049] According to the above configuration, the distance X between the rotation axis and the position of the specific circle detected by the linear encoder can be obtained, and the eccentricity angle θ, which is the angle between the line on which the linear encoder detects the position and the eccentricity direction of the drum, can be obtained from the rotation angle of the rotating shaft detected by the rotary encoder. The eccentricity amount e of the drum can be calculated by using the radius Rd of the specific circle in addition to the distance X and the eccentricity angle θ. Therefore, the eccentricity amount e of the drum can be measured.

[0050] As a second aspect, in the first aspect, the at least one linear encoder may include two linear encoders spaced apart from each other in a circumferential direction about the rotation axis. With this configuration, the eccentricity amount e of the drum can be calculated appropriately regardless of the value of the eccentricity angle θ of the drum.

[0051] As a third aspect, in the first or second aspect, the housing may include an annular portion surrounding the rotation space of the drum, and a plurality of boss portions protruding from the annular portion in a radial direction about the rotation axis and forming the plurality of cylinder bores together with the annular portion, and the at least one linear encoder may be attached to the annular portion between the plurality of boss portions. With this configuration, the space between the boss portions can be effectively used as a placement space for the linear encoder.

[0052] As a fourth aspect, in any of the first to third aspects, for example, the at least one linear encoder may include a linear encoder body fixed to the housing, a rod supported by the linear encoder body so as to be slidable in a radial direction centered on the rotation axis, a carriage attached to the end of the rod, and a roller attached to the carriage, and the roller may fit into an annular groove formed in the drum or an accessory of the drum along the specific circle, or roll on the outer circumferential surface of the drum.

[0053] As a fifth aspect, in the fourth aspect, the at least one linear encoder may include a guide that guides the movement of the carriage in a radial direction around the rotation axis. With this configuration, the eccentricity e of the drum can be measured with high accuracy.

[0054] As a sixth aspect, in any of the first to fifth aspects, for example, the hydraulic rotating machine may further include a plurality of connection rods each connected to the plurality of pistons and sliding on an outer circumferential surface of the drum. [Explanation of symbols]

[0055] 1. Hydraulic Rotating Machinery 13 Rotating Space 2 Rotating shaft 20 Rotational Axis 3 Eccentricity adjustment machine 4 Drums 40 center 45 Drum Plate 46 Annular groove 5. Housing 50 Cylinder bore 51 Circular section 52 Boss section 61 Piston 62 Connection Rod 84 Rotary Encoder 9 Linear Encoder 92 Linear Encoder Body 93 Rod 94 Carriage 95 Lola 96 Guide

Claims

1. A radial piston type hydraulic rotary machine, A rotating shaft extending along a rotation axis; a housing including a plurality of cylinder bores arranged radially around the rotation axis; a drum that rotates together with the rotating shaft to reciprocate a plurality of pistons disposed in the plurality of cylinder bores, respectively; an eccentricity adjuster for adjusting an eccentricity of the drum, the eccentricity being the distance from the rotation shaft to the center of the drum; a rotary encoder for detecting a rotation angle of the rotating shaft; At least one linear encoder for detecting the position of a specific circle concentric with the drum on a straight line perpendicular to the rotation axis; A hydraulic rotating machine comprising:

2. The hydraulic rotating machine according to claim 1 , wherein the at least one linear encoder includes two linear encoders spaced apart from each other in a circumferential direction about the rotational axis.

3. the housing includes an annular portion surrounding a rotation space of the drum, and a plurality of boss portions protruding from the annular portion in a radial direction about the rotation axis and forming the plurality of cylinder bores together with the annular portion, The hydraulic rotating machine according to claim 1 or 2, wherein the at least one linear encoder is attached to the annular portion between the plurality of boss portions.

4. the at least one linear encoder includes a linear encoder body fixed to the housing, a rod supported by the linear encoder body so as to be slidable in a radial direction about the rotation axis, a carriage attached to a tip of the rod, and a roller attached to the carriage, 3. The hydraulic rotary machine according to claim 1, wherein the rollers are fitted into annular grooves along the specific circle formed in the drum or an attachment of the drum, or roll on the outer circumferential surface of the drum.

5. The hydraulic rotating machine of claim 4 , wherein the at least one linear encoder includes a guide for guiding movement of the carriage in a radial direction about the axis of rotation.

6. The hydraulic rotating machine according to claim 1 or 2, further comprising a plurality of connection rods each connected to the plurality of pistons and sliding on an outer circumferential surface of the drum.

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