CN218816804U - Fluid machinery - Google Patents

Abstract

The utility model relates to a fluid machine. Sufficient durability can be obtained. A hydraulic pump (1) according to an embodiment is provided with: a cylinder block (4) which is provided so as to be rotatable about a central axis, in which a plurality of cylinder chambers (17) are arranged in a rotational direction in a row along the central axis, and in which the cylinder block (4) has a communication hole (18) that communicates the bottom sections (17 a) of the plurality of cylinder chambers (17) with the outside; and a piston (21) inserted into the cylinder chamber (17) so as to be able to reciprocate, and a pressure chamber (13) formed between the piston (21) and the cylinder chamber (17). The hydraulic pump (1) is provided with a rounded portion (17 b) of a cylinder chamber (17), and when the circular arc radius of the rounded portion (17 b) is R and the inner diameter of the cylinder chamber (17) is Dc, the circular arc radius R and the inner diameter Dc satisfy 0.012 ≦ R/Dc ≦ 0.045.

Description

Fluid machinery

Technical Field

The utility model relates to a fluid machine.

Background

As the fluid machine, for example, a hydraulic motor and a hydraulic pump are available. For example, the main structure of the hydraulic motor is: a housing; a shaft rotatably supported by the housing and coupled to a load; a cylinder body disposed in the housing and fixed to the shaft; a piston housed in a cylinder chamber formed in a cylinder block; and a swash plate for sliding the pistons. The surface of the swash plate on which the pistons slide is inclined with respect to a direction orthogonal to the axial direction of the shaft.

The cylinder chamber is formed in a concave shape between positions slightly forward from one end in the axial direction of the cylinder block to the other end in the axial direction. A piston is housed in the cylinder chamber so as to be capable of reciprocating. A pressure chamber is formed between the piston and the cylinder chamber. When the hydraulic oil is supplied to the pressure chamber, the hydraulic pressure in the pressure chamber increases, and the piston moves so as to protrude from one end in the axial direction of the cylinder. At this time, the force of the pistons pressing the swash plate is converted into a rotational force to rotate the cylinder block and the shaft.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2020-159272

SUMMERY OF THE UTILITY MODEL

Problem to be solved by utility model

Further, the volume of the pressure chamber (the amount of hydraulic oil supplied to the pressure chamber from the pressure chamber) and the cross-sectional area of the piston (the area of the end surface of the piston on which the pressure of the hydraulic oil acts) are determined based on the output of the shaft to be obtained, and thereby the design values of the cylinder chamber and the piston are determined.

However, design values of portions that do not significantly affect the volume of the pressure chamber, such as the inner peripheral edge of the bottom portion of the cylinder chamber (the corner portion of the bottom portion of the cylinder chamber), are often determined by the machining accuracy of the machining equipment, and are not limited thereto. Therefore, there is a case where sufficient durability of the fluid machine cannot be obtained due to cracks or the like generated in the cylinder block due to a high load applied to the fluid machine or the like.

The utility model provides a can obtain sufficient durability's fluid machinery.

Means for solving the problems

The utility model discloses a technical scheme's fluid machinery possesses: a cylinder block which is provided rotatably about a rotation axis, in which a plurality of cylinder chambers are arranged in a rotational direction along the rotation axis, and which has a communication hole for communicating bottoms of the plurality of cylinder chambers in the rotation axis direction with the outside; and a piston inserted into the cylinder chamber so as to be capable of reciprocating, a pressure chamber being formed between the piston and the cylinder chamber, an indoor chamfered portion being formed on an inner peripheral edge of the bottom portion of the cylinder chamber, and the circular arc radius R and the inner diameter Dc satisfying 0.012. Ltoreq.R/Dc.ltoreq.0.045 when the circular arc radius of the indoor chamfered portion is R and the inner diameter of the cylinder chamber is Dc.

With this configuration, a cylinder capable of withstanding a high load and sufficiently obtaining durability can be provided. Therefore, a fluid machine capable of withstanding a high load and sufficiently obtaining durability can be provided.

In the above structure, the arc radius R and the inner diameter Dc may satisfy 0.018. Ltoreq.R/Dc. Ltoreq.0.04.

In the above structure, the arc radius R and the inner diameter Dc may satisfy 0.025. Ltoreq. R/Dc. Ltoreq.0.035.

The utility model discloses a fluid machinery of another technical scheme possesses: a cylinder block which is provided rotatably about a rotation axis, in which a plurality of cylinder chambers are arranged in a rotational direction along the rotation axis, and which has a communication hole for communicating bottoms of the plurality of cylinder chambers in the rotation axis direction with the outside; and a piston inserted into the cylinder chamber so as to be capable of reciprocating, a pressure chamber being formed between the piston and the cylinder chamber, an indoor rounded portion being formed on an inner peripheral edge of the bottom portion of the cylinder chamber, and the arc radius R and the stress sigma satisfying 150 (MPa/mm) ≦ sigma/R ≦ 900 (MPa/mm) when the arc radius of the indoor rounded portion is R (mm) and the stress applied to the indoor rounded portion is sigma (MPa).

With this configuration, a cylinder capable of withstanding a high load capacity and sufficiently obtaining durability can be provided. Therefore, a fluid machine capable of withstanding a high load and sufficiently obtaining durability can be provided.

In the above structure, the arc radius R and the stress σ may satisfy 150 (MPa/mm) ≦ σ/R ≦ 600 (MPa/mm).

In the above structure, the arc radius R and the stress σ may satisfy 150 (MPa/mm) ≦ σ/R ≦ 300 (MPa/mm).

The utility model discloses a fluid machinery of another technical scheme possesses: a cylinder block which is provided rotatably around a rotation axis, in which a plurality of cylinder chambers are arranged in a rotational direction along the rotation axis, and which has a communication hole for communicating bottoms of the plurality of cylinder chambers in the rotation axis direction with the outside; and a piston inserted into the cylinder chamber so as to be capable of reciprocating, a pressure chamber being formed between the piston and the cylinder chamber, an indoor chamfered portion being formed on an inner peripheral edge of the bottom portion of the cylinder chamber, and an arc radius R and a wall thickness t satisfying 2 (mm) when an arc radius of the indoor chamfered portion is R (mm) and a wall thickness on the bottom portion side of the cylinder chamber of the cylinder body is t (mm) ² )≤t×R≤10(mm ² )。

With such a configuration, a cylinder capable of withstanding a high load and sufficiently obtaining durability can be provided. Therefore, a fluid machine capable of withstanding a high load and sufficiently obtaining durability can be provided.

In the above-described structure, the arc radius R and the wall thickness t may satisfy 4 (mm) ² )≤t×R≤9.5(mm ² )。

In the above configuration, the arc radius R and the wall thickness t may satisfy 6 (mm) ² )≤t×R≤9(mm ² )。

The utility model discloses a fluid machinery of another technical scheme possesses: a housing having a suction passage through which a fluid is sucked and a discharge passage through which the fluid is discharged; a cylinder block which is housed in the housing so as to be rotatable about a rotation axis, in which a plurality of cylinder chambers are arranged in a rotational direction along the rotation axis direction, and which has a communication hole that communicates bottoms of the plurality of cylinder chambers in the rotation axis direction with the suction passage and the discharge passage; and a piston inserted into the cylinder chamber so as to be able to reciprocate, a pressure chamber being formed between the piston and the cylinder chamber, an indoor rounded portion being formed on an inner peripheral edge of the bottom portion of the cylinder chamber, and the circular arc radius R and the inner diameter Dc satisfying 0.012 < R/Dc < 0.045 when R is a circular arc radius of the indoor rounded portion and Dc is an inner diameter of the cylinder chamber.

With this configuration, a cylinder capable of withstanding a high load and sufficiently obtaining durability can be provided. Therefore, a fluid machine capable of withstanding a high load and sufficiently obtaining durability can be provided.

Effect of the utility model

The fluid machine described above can obtain sufficient durability.

Drawings

Fig. 1 is a sectional view of a hydraulic pump according to an embodiment of the present invention.

Fig. 2 is a perspective view of a cylinder block according to an embodiment of the present invention.

Fig. 3 is a view in direction III of fig. 2.

Fig. 4 is an enlarged view of a portion IV of fig. 1.

Description of the reference numerals

1. A hydraulic pump (fluid machine); 4. a cylinder body; 4c, a bottom wall; 13. a pressure chamber; 17. a cylinder chamber; 17a, a bottom; 17b, a rounded portion (indoor rounded portion); 21. a piston; 21c, a rounded portion (piston rounded portion); 91. a suction passage; 92. an ejection passage; C. central axis (rotation axis).

Detailed Description

Next, embodiments of the present invention will be described based on the drawings.

< Hydraulic Pump >

Fig. 1 is a sectional view of a hydraulic pump 1 as a fluid machine.

As shown in fig. 1, the hydraulic pump 1 is a so-called swash plate type variable displacement hydraulic pump. The hydraulic pump 1 includes: a housing 2; a shaft 3 rotatably supported inside the housing 2; a cylinder 4 housed inside the housing 2 and fixed to the shaft 3; a swash plate 5 that is housed in the casing 2 so as to be variable in inclination angle and controls the discharge amount of the hydraulic oil discharged from the hydraulic pump 1; and a piston 21 housed in the cylinder 4.

In fig. 1, the scale of each member is appropriately changed to make the description easy to understand. In the following description, a direction parallel to the center axis C of the shaft 3 (an example of the rotation axis of the claims) is referred to as an axial direction, a rotation direction of the shaft 3 is referred to as a circumferential direction, and a radial direction of the shaft 3 is simply referred to as a radial direction.

< housing >

The housing 2 includes: a box-shaped case body 9 having an opening; and a front flange 10 for closing the opening of the housing main body 9. One end 3a of the shaft 3 is rotatably supported by a bottom portion 9a of the casing main body 9 on the side opposite to the opening (the right side in fig. 1). Further, a suction passage 91 and a discharge passage 92 are formed in the bottom portion 9a of the housing main body 9. The suction passage 91 communicates with a tank not shown. The discharge passage 92 communicates with a hydraulic actuator (neither shown) via a control valve, for example. Examples of the hydraulic actuator include a hydraulic motor and a hydraulic cylinder.

A swash plate support portion 30 is formed on the front flange 10 so as to protrude from an inner surface 10a on the housing main body 9 side. The swash plate support portion 30 supports the swash plate 5 at a variable inclination angle. The inclination angle of the swash plate 5 is controlled by an inclination angle control unit, not shown. The tilt angle control unit is driven based on an operation signal of an operator, for example.

The other end 3b of the shaft 3 is rotatably supported by the front flange 10. A power source such as an engine, not shown, is connected to the other end 3b of the shaft 3. A spline groove 3c is formed in the outer peripheral surface of the shaft 3 at the center in the axial direction. The cylinder 4 is fitted to the outer peripheral surface of the shaft 3 via the spline grooves 3c.

< cylinder body >

Fig. 2 is a perspective view of the cylinder 4. Fig. 3 is a view in direction III of fig. 2.

As shown in fig. 1 to 3, the cylinder 4 is formed in a cylindrical shape. A through hole 16 into which the shaft 3 can be inserted or press-fitted is formed at the radial center of the cylinder 4. A spline groove 16a is also formed in the through hole 16. The spline grooves 16a are spline-coupled with the spline grooves 3c of the shaft 3. Thereby, the shaft 3 rotates integrally with the cylinder 4.

The cylinder block 4 has a plurality of cylinder chambers 17 formed to surround the shaft 3. The cylinder chambers 17 are arranged at equal intervals in the circumferential direction. The cylinder chamber 17 is formed in a concave shape along the axial direction between a 1 st end surface 4a of the cylinder block 4 on the front flange 10 side and a slightly forward position of a 2 nd end surface 4b on the bottom 9a side of the housing main body 9. The front flange 10 side of the cylinder chamber 17 is open. Communication holes 18 for communicating the cylinder chambers 17 with the outside of the cylinder block 4 (the 2 nd end surface 4 b) are formed in the bottom wall 4c of the cylinder block 4 on the 2 nd end surface 4b side at positions corresponding to the cylinder chambers 17.

A disc-shaped valve plate 19 is provided on the 2 nd end surface 4b of the cylinder block 4 so as to overlap the 2 nd end surface 4 b. The valve plate 19 is fixed to the housing main body 9. The valve plate 19 is stationary with respect to the housing 2 (housing main body 9) even when the cylinder block 4 rotates together with the shaft 3.

The valve plate 19 has a suction port 19a and a discharge port 19b that communicate with the communication holes 18 of the cylinder block 4 and extend through the valve plate 19 in the thickness direction. Each cylinder chamber 17 communicates with the suction passage 91 of the housing main body 9 via the suction port 19a of the valve plate 19 and the communication hole 18 of the cylinder block 4. Each cylinder chamber 17 communicates with the discharge passage 92 via the discharge port 19b of the valve plate 19 and the communication hole 18 of the cylinder block 4.

The valve plate 19 is fixed with respect to the housing main body 9. Therefore, the cylinder chamber 17 switches between a state in which the hydraulic oil is supplied from the suction passage 91 via the valve plate 19 and a state in which the hydraulic oil is discharged to the discharge passage 92 in accordance with the rotation state of the cylinder block 4.

< piston >

A piston 21 is housed in each cylinder chamber 17 so as to be capable of reciprocating in the axial direction. As piston 21 is housed in cylinder chamber 17, piston 21 revolves around central axis C of shaft 3 in accordance with the rotation of shaft 3 and cylinder 4.

A spherical convex portion 28 is integrally formed at the 1 st end portion 21a of the piston 21 on the swash plate 5 side. The convex portion 28 of the piston 21 slides on the sliding surface 5a of the swash plate 5 via the shoe 22 provided on the convex portion 28.

A recess 41 is formed in the 2 nd end 21b of the piston 21 on the bottom 17a side of each cylinder chamber 17. The recess 41 is formed in a concave shape along the axial direction between the 2 nd end portion 21b and the 1 st end portion 21a of the piston 21. The 2 nd end 21b side of the recess 41 is open.

Further, the protruding portion 28 of the piston 21 is formed with a through hole 28a that communicates the recessed portion 41 with the outside of the protruding portion 28 in the axial direction.

The recess 41 and the through hole 28a are filled with the hydraulic oil in the cylinder chamber 17. The piston 21 forms a pressure chamber 13 in which the pressure of the working oil acts between the piston and the cylinder chamber 17. Thus, the reciprocation of the piston 21 is associated with the suction and discharge of the hydraulic oil with respect to the cylinder chamber 17. That is, when the piston 21 is pulled out from the cylinder chamber 17, the pressure of the pressure chamber 13 decreases, and the working oil is supplied from the suction passage 91 into the cylinder chamber 17. When the piston 21 enters the cylinder chamber 17, the pressure in the pressure chamber 13 increases, and the hydraulic oil is discharged from the cylinder chamber 17 to the discharge passage 92. The operation of the hydraulic pump 1 will be described in detail below.

< action of hydraulic pump >

The hydraulic pump 1 outputs a driving force generated by discharge of the hydraulic oil from the cylinder chamber 17 (and suction of the hydraulic oil into the cylinder chamber 17).

More specifically, first, the shaft 3 is rotated by power from a power source such as an engine, and the cylinder block 4 and the shaft 3 are rotated integrally. The piston 21 revolves around the central axis C of the shaft 3 as the cylinder 4 rotates.

The shoes 22 attached to the convex portions 28 of the pistons 21 slide along the sliding surface 5a of the swash plate 5 regardless of the inclination angle of the swash plate 5. Each shoe 22 slides while revolving around the central axis C of the shaft 3. The shoes 22 and the protrusions 28 maintain the posture of the piston 21 in the axial direction regardless of the inclination angle of the swash plate 5.

Thereby, each piston 21 moves in the axial direction in each cylinder chamber 17, and each piston 21 reciprocates. In this way, the swash plate 5 restricts the axial movement of each piston 21. By the reciprocating motion of the piston 21, the hydraulic oil is discharged from some of the cylinder chambers 17, and the hydraulic oil is sucked into the other cylinder chambers 17, thereby realizing a hydraulic pump.

In this way, the pressure in the pressure chamber 13 formed by each cylinder chamber 17 and the piston 21 greatly changes with the rotation of the shaft 3. The stress acting on the cylinder block 4 (cylinder chamber 17) due to the pressure becomes a factor of damaging the cylinder block 4 and reducing the durability of the cylinder block 4. Therefore, the dimensions of the cylinder 4 and the piston 21 are defined below.

< specification of size of main portion of cylinder and piston >

Fig. 4 is an enlarged view of a portion IV of fig. 1.

That is, as shown in fig. 4, a bottom portion 17a of the cylinder chamber 17 has a rounded portion (an example of an indoor rounded portion in the claims) 17b formed on an inner peripheral edge. In other words, the rounded portion 17b of the cylinder chamber 17 is an arc-shaped recess formed over the entire circumference at the corner of the bottom 17a of the cylinder chamber 17.

A round portion (an example of a piston round portion in the claims) 21c is formed on the outer peripheral edge of the 2 nd end portion 21b of the piston 21. In other words, the rounded portion 21c of the piston 21 is an arc-shaped corner portion formed over the entire circumference at the corner of the 2 nd end portion 21 b.

When the arc radius of the rounded portion 17b of the cylinder chamber 17 is defined as R and the inner diameter of the cylinder chamber 17 is defined as Dc, the arc radius R and the inner diameter Dc satisfy

0.012≤R/Dc≤0.045···(1)。

As shown in detail in fig. 4, the cylinder chamber 17 is formed such that the inner diameter Dc of a part of the bottom portion 17a is slightly larger than the inner diameter Dc of the other part. The slightly larger portion is a relief portion 17d for polishing a sliding surface 17c between the inner circumferential surface of the cylinder chamber 17 and the outer circumferential surface of the piston 21. The inner diameter Dc of the cylinder chamber 17 in the above formula (1) is the inner diameter of the sliding surface 17c of the cylinder chamber 17. The same applies to the following formulae.

Desirably, the circular arc radius R of the rounded corner portion 17b and the inner diameter Dc of the cylinder chamber 17 satisfy

0.018≤R/Dc≤0.04···(2)。

Further, it is further desirable that the circular arc radius R of the rounded corner portion 17b and the inner diameter Dc of the cylinder chamber 17 satisfy

0.025≤R/Dc≤0.035···(3)。

When the radius of the rounded portion 17b is R (mm) and the stress acting on the rounded portion 17b is σ (MPa), the radius of the arc R and the stress σ satisfy

150(MPa/mm)≤σ/R≤900(MPa/mm)···(4)。

The stress σ acting on the rounded portion 17b is a stress obtained by summing up all the stresses acting on the rounded portion 17b at the time of measuring the stress, and includes a stress acting on the rounded portion 17b due to the pressure of the hydraulic oil filled in the pressure chamber 13, a stress acting on the rounded portion 17b when the cylinder 4 rotates integrally with the shaft 3, a stress acting on the rounded portion 17b when the piston 21 reciprocates in the cylinder chamber 17, and the like. The same applies to the following formulae. Further, as a method of measuring the stress, for example, CAE analysis and the like can be cited.

In addition, it is desirable that the radius R (mm) of the rounded corner portion 17b and the stress σ (MPa) acting on the rounded corner portion 17b satisfy

150(MPa/mm)≤σ/R≤600(MPa/mm)···(5)。

Further, it is further desirable that the radius R (mm) of the rounded corner portion 17b and the stress σ (MPa) acting on the rounded corner portion 17b satisfy

150(MPa/mm)≤σ/R≤300(MPa/mm)···(6)。

When the radius of the rounded portion 17b is R (mm) and the thickness of the bottom 17a side of the cylinder chamber 17 of the cylinder block 4, that is, the thickness of the bottom wall 4c of the cylinder block 4 is t (mm), the radius of the radius R and the thickness t satisfy

2(mm ² )≤t×R≤10(mm ² )···(7)。

Further, the thickness t refers to the thickness of the bottom wall 4c in the axial direction. The same applies to the following formulae.

Further, it is desirable that the radius R (mm) of the rounded corner portion 17b and the wall thickness t (mm) of the bottom wall 4c of the cylinder block 4 satisfy

4(mm ² )≤t×R≤9.5(mm ² )···(8)。

Further, it is further desirable that the radius R (mm) of the rounded corner portion 17b and the wall thickness t (mm) of the bottom wall 4c of the cylinder block 4 satisfy

6(mm ² )≤t×R≤9(mm ² )···(9)。

Further, the radius R of the rounded portion 17b of the cylinder chamber 17 is formed to have a size such that the rounded portion 17b of the cylinder chamber 17 does not contact the rounded portion 21c of the piston 21 in a state where the piston 21 is at the bottom dead center. Under such conditions, it is desirable that the circular arc radius R of the rounded portion 17b of the cylinder chamber 17 be as large as possible. The bottom dead center of the piston 21 is a position of the piston 21 at a time point when the piston 21 enters the cylinder chamber 17 to the maximum extent during 1 rotation of the cylinder 4 about the center axis C.

Therefore, according to the above embodiment, by satisfying any one of the above equations (1) to (9), the cylinder block 4 that can withstand a high load and can sufficiently obtain durability can be provided. Therefore, the hydraulic pump 1 can withstand a high load and can sufficiently obtain durability.

Further, the radius R of the rounded portion 17b of the cylinder chamber 17 is formed to have a size such that the rounded portion 17b of the cylinder chamber 17 does not contact the rounded portion 21c of the piston 21 in a state where the piston 21 is at the bottom dead center. With this configuration, the cylinder 4 can be provided that can withstand a high load and can sufficiently obtain durability. Therefore, the hydraulic pump 1 can withstand a high load and can sufficiently obtain durability.

The present invention is not limited to the above-described embodiments, and includes embodiments in which various modifications are made to the above-described embodiments without departing from the scope of the present invention.

For example, in the above-described embodiment, the hydraulic pump 1 is described as an example of the fluid machine. However, the present invention is not limited to this, and the above-described embodiments can be applied to various fluid machines including a cylinder block having a cylinder chamber and a piston accommodated in the cylinder chamber, such as a hydraulic motor, a pump using a fluid other than hydraulic oil, a motor, and the like. The fluid is not limited to liquid, and may be gas.

In the embodiments disclosed in the present specification, a member made of a plurality of objects may be formed by integrating the plurality of objects, and conversely, a member made of one object may be divided into a plurality of objects. Whether integrated or not, the structure may be configured to achieve the object of the invention.

Claims (10)

1. A fluid machine characterized in that a fluid flow path is formed,

the fluid machine includes:

a cylinder block which is provided rotatably about a rotation axis, in which a plurality of cylinder chambers are arranged in a rotational direction along the rotation axis, and which has a communication hole for communicating bottoms of the plurality of cylinder chambers in the rotation axis direction with the outside; and

a piston inserted into the cylinder chamber so as to be capable of reciprocating, a pressure chamber being formed between the piston and the cylinder chamber,

an indoor chamfered portion is formed on an inner peripheral edge of the bottom portion of the cylinder chamber,

when the radius of the inner rounded corner is R and the inner diameter of the cylinder chamber is Dc,

the arc radius R and the inner diameter Dc satisfy 0.012-R/Dc-0.045.

2. Fluid machine according to claim 1,

the arc radius R and the inner diameter Dc satisfy 0.018-0.04 of R/Dc.

3. Fluid machine according to claim 2,

the arc radius R and the inner diameter Dc satisfy 0.025-0.035.

4. A fluid machine characterized in that a fluid flow path is formed,

the fluid machine includes:

a cylinder block which is provided rotatably about a rotation axis, in which a plurality of cylinder chambers are arranged in a rotational direction along the rotation axis, and which has a communication hole for communicating bottoms of the plurality of cylinder chambers in the rotation axis direction with the outside; and

a piston inserted into the cylinder chamber so as to be capable of reciprocating, a pressure chamber being formed between the piston and the cylinder chamber,

an indoor chamfered portion is formed on an inner peripheral edge of the bottom portion of the cylinder chamber,

when the radius of the arc of the indoor chamfer is R and the stress acting on the indoor chamfer is sigma, wherein the unit of R is mm and the unit of sigma is MPa,

the arc radius R and the stress sigma meet the condition that the stress sigma/R is more than or equal to 150MPa/mm and less than or equal to 900MPa/mm.

5. Fluid machine according to claim 4,

the arc radius R and the stress sigma meet the requirement that sigma/R is more than or equal to 150MPa/mm and less than or equal to 600MPa/mm.

6. Fluid machine according to claim 5,

the arc radius R and the stress sigma meet the condition that the stress sigma/R is more than or equal to 150MPa/mm and less than or equal to 300MPa/mm.

7. A fluid machine characterized in that a fluid flow path is formed,

the fluid machine includes:

a cylinder block which is provided rotatably around a rotation axis, in which a plurality of cylinder chambers are arranged in a rotational direction along the rotation axis, and which has a communication hole for communicating bottoms of the plurality of cylinder chambers in the rotation axis direction with the outside; and

a piston inserted into the cylinder chamber so as to be capable of reciprocating, a pressure chamber being formed between the piston and the cylinder chamber,

an indoor chamfered portion is formed on an inner peripheral edge of the bottom portion of the cylinder chamber,

when the radius of the inner rounded corner is R and the thickness of the bottom side of the cylinder chamber of the cylinder block is t, where R is mm and t is mm,

the arc radius R and the wall thickness t meet 2mm ² ≤t×R≤10mm ² 。

8. Fluid machine according to claim 7,

the arc radius R and the wall thickness t meet 4mm ² ≤t×R≤9.5mm ² 。

9. Fluid machine according to claim 7,

the arc radius R and the wall thickness t meet 6mm ² ≤t×R≤9mm ² 。

10. A fluid machine characterized in that a fluid flow path is formed,

the fluid machine includes:

a housing having a suction passage through which a fluid is sucked and a discharge passage through which the fluid is discharged;

a cylinder block which is housed in the housing so as to be rotatable about a rotation axis, in which a plurality of cylinder chambers are arranged in a rotational direction along the rotation axis direction, and which has a communication hole that communicates bottoms of the plurality of cylinder chambers in the rotation axis direction with the suction passage and the discharge passage; and

a piston inserted into the cylinder chamber so as to be capable of reciprocating, a pressure chamber being formed between the piston and the cylinder chamber,

an indoor chamfered portion is formed on an inner peripheral edge of the bottom portion of the cylinder chamber,

when the radius of the inner rounded corner is R and the inner diameter of the cylinder chamber is Dc,

the arc radius R and the inner diameter Dc satisfy 0.012-R/Dc-0.045.

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