JP3008602B2 - piston - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston used for a piston pump or a piston motor.

[0002]

2. Description of the Related Art In recent years, the weight of a piston used for a piston pump or a piston motor has been required to be further reduced with the increase in pressure and speed of the piston pump and the piston motor. FIG. 2 is a cross-sectional view showing an example of a conventional piston whose weight has been reduced. This piston has a hollow structure to reduce its weight, and has a spherical head 31 to which a piston shoe 30 is attached, and a connecting base 32 connected to the head 31.
And a cylindrical sleeve 33 connected to the connecting base 32 and having a rear end opened, and further formed with a lubrication passage 35 communicating from the hollow portion 34 to the tip of the head 31. ing. This piston is suitable for high speed operation because of its light weight.
As a result, the volume efficiency of the pump or the motor is reduced by the volume of the hollow portion 34.

Therefore, conventionally, as shown in FIG. 3, a piston has been proposed in which a hollow structure is used to reduce the weight, and a rear end portion is closed to prevent fluid from entering the hollow portion to improve the volumetric efficiency. (Japanese Patent Laid-Open No. 50-97902). This piston is connected to the main body 4 on the left side of the dashed line 60.
In FIG. 2, the right end 50 is joined by inertial welding. That is, the main body 40 has a spherical head 41, a connection base 42 connected to the head, a central support 43 and a cylindrical sleeve 44 connected to the connection base, and a rear end of the central support 43. A lubrication passage 45 is formed at the tip of the head 41 and an annular gap 46 is formed between the central support 43 and the sleeve 44.
0, an end wall 51 and a central projection 52 connected to the end wall 51.
And a lubricating passage 54 which is open at the rear end of the end wall 51 and the front end of the central projection 52.
Gap 5 between the central projection 52 and the annular projection wall 53
5, a central projection 43 of the end 50 is joined to the central support 43 of the main body 40, and an annular projecting wall 53 of the end 50 is joined to the cylindrical sleeve 44 of the main body 40. The washer 70 inserted in the annular gap 46 is a reinforcing material for preventing deformation or the like during processing or inertia welding. The piston formed in this way is lightweight, so that it is suitable for high pressure and high speed. In addition, since the fluid does not enter the hollow portion (the annular gaps 46 and 55), the volume efficiency is improved.

[0004]

However, this piston has a welded joint formed by inertial welding.
There is a problem that rigidity is reduced and breakage easily occurs, and a special dedicated tool (a cutting tool or a processing machine) is required for processing the annular gap, and the number of processing steps is increased. Therefore, an object of the present invention is to provide a piston which has no welded portion, can be easily processed with a standard tool, is lightweight, and has good volumetric efficiency.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to a piston used for a piston pump or a piston motor, which comprises a substantially spherical head 5 to which a piston shoe is attached, 5 and a cylindrical sleeve 7 connected to the connection base 6 and having an open rear end are integrally formed. A space 8 surrounded by the sleeve 7 is connected to the connection base 6. The lubrication passage 1 has a cylindrical concave portion 10 that opens, and opens at the tip end surface of the head 5 and the bottom surface of the concave portion 10.
1 and a pipe-shaped member 2 having one end press-fitted into the recess 10 and brazed (A) to the connection base 6 and further having a lubrication passage 12 opened at one end and the other end. And press-fitted between the end of the sleeve 7 and the other end of the pipe-shaped member 12 and brazed (B, C) to the sleeve 7 and the pipe-shaped member 2 to close the space 8 It is characterized by comprising the lid member 3.

[0006]

The piston having the above construction has a space 8 surrounded by a connecting base 6 and a cylindrical sleeve 7, so that the piston can be made lighter, and the pressure of the piston pump and piston motor can be reduced.
Suitable for speeding up. Further, since the space 8 is covered with the lid member 3 so that fluid does not enter the space 8, the volume efficiency of the piston pump and the piston motor is improved. Further, since the joining of the main body member 1, the pipe-shaped member 2, and the lid member 3 is performed by brazing, there is no welded joint, and therefore, the rigidity is not reduced and the reliability against breakage and the like is improved. Further, since the shape of the processing portion is cylindrical, no special tool is required for the processing, and the number of processing steps may be reduced.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 is a sectional view of one embodiment of the present invention.
This piston is composed of three members, a main body member 1, a pipe-shaped member 2, and a lid member 3. The main body member 1 includes:
A spherical head 5, a connecting base 6 connected to the head, and a cylindrical sleeve 7 connected to the connecting base 6 and having an open rear end are integrally formed. The coupling base 6 has a cylindrical concave portion 10 that opens into a space 8 surrounded by the coupling base 6 and the sleeve 7.
The lubrication passage 11 has an opening at a bottom surface of the recess 10 and a tip end surface of the head. The pipe-shaped member 2 has an outer diameter substantially equal to the inner diameter of the recess 10 and has a lubrication passage 12 opened at one end and the other end. The perimeter is brazed to the connection base. A indicates the brazing point. The cover member 3 is formed in a donut shape having an outer diameter substantially equal to the inner diameter of the rear end of the sleeve 7 and an inner diameter substantially equal to the outer diameter of the pipe-shaped member 2. Then, after being press-fitted to a position where the sleeve is locked by the locking portion 13, the outer peripheral portion and the inner peripheral portion of the rear surface are brazed to the sleeve 7 and the pipe-shaped member 2, respectively. B indicates the brazing point.

The piston assembled in this way has a space 8 so that it is lightweight and can be used for a high-pressure / high-speed pump or motor. Further, the space portion 8 is
2 to prevent fluid from entering the space, so that the volumetric efficiency of the pump or motor is improved as compared with the piston of FIG. Furthermore, since the joining between the main body member 1 and the pipe-shaped member 2 and the joining between the lid member 3 and the main body member 1 and the pipe-shaped member 2 are performed by brazing, there is no welded joint portion. The rigidity is higher than that of the piston, and the reliability against breakage and the like is improved. In addition, since the joining by brazing can be performed in a large amount at a time by a brazing furnace, the joining process can be shortened and the productivity is improved. Further, since the piston of FIG. 3 requires machining of the annular gaps 46 and 55, a special special cutting tool and a processing machine are required, and the number of processing steps is increased. Since simple machining can be performed simply by drilling holes on the cylinder, standard tools can be used, and the number of machining steps is reduced.

[0009]

As is apparent from the above description, the piston of the present invention has a substantially spherical head to which the piston shoe is attached, a connecting base connected to the head, a connecting base connected to the connecting base and an open rear end. A cylindrical sleeve is integrally formed, and the connecting base has a cylindrical concave portion that opens to a space surrounded by the sleeve, and opens at the tip end surface of the head and the bottom surface of the concave portion. A main body member having a lubrication passage, a pipe-shaped member having a lubrication passage opening at one end and the other end, wherein one end is press-fitted into the concave portion and brazed to the connection base;
The sleeve is press-fitted between the end of the sleeve and the other end of the pipe-shaped member, and is formed by the sleeve and the lid member that is brazed to the pipe-shaped member and closes the space. It has the following effects. Since it has a space surrounded by the connecting base and the sleeve, it is possible to reduce the weight, and therefore to increase the pressure and speed of the piston pump and the piston motor. Since the space is covered with the lid member so that fluid does not enter the space, the volume efficiency of the piston pump and the piston motor is improved. Since the joining of the main body member, the pipe-shaped member and the lid member is performed by brazing, there is no welded joint, so that the rigidity is not reduced and the reliability against breakage and the like is improved. Further, since a large amount of bonding can be performed at once by using a brazing furnace, the bonding process can be shortened, and the productivity is improved. Since the shape of the processing portion is cylindrical, a special tool is not required for processing, and the number of processing steps may be small.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a conventional example in which one end of a hollow portion is open.

FIG. 3 is a sectional view of a conventional example in which a hollow portion is closed by inertial welding.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Body member, 2 ... Pipe-shaped member, 3 ... Lid member, 5 ... Head, 6 ... Connection base, 7 ... Sleeve, 8 ... Space, 10 ...
Recesses, 11, 12: Lubrication passage.

Continuation of the front page (72) Inventor Masaaki Hiraoka 1-1, Nishiichitsuya, Settsu-shi, Osaka Daikin Industries, Ltd. Yodogawa Works (56) References JP-A-50-97902 (JP, A) JP-A-62 71355 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F04B 1/00-23/14

Claims (1)

(57) [Claims] A piston used in a piston pump or a piston motor, comprising a substantially spherical head (5) to which a piston shoe is attached;
A connecting base (6) connected to the head (5) and the connecting base;
A cylindrical sleeve connected to (6) and having an open rear end
(7) are integrally formed, the connecting base (6) has a cylindrical concave portion (10) opened to a space (8) surrounded by the sleeve (7), and the head has Lubrication passageway (11) opening at the tip end surface of (5) and the bottom surface of recess (10)
A lubrication passage (12) having one end press-fitted into the recess (10) and brazed (A) to the connection base (6), and further open at one end and the other end. Pipe-shaped member (2)
And press-fitted between the end of the sleeve (7) and the other end of the pipe-shaped member (12) and brazed (B, C) to the sleeve (7) and the pipe-shaped member (2). Being the above space
(8) A piston comprising a lid member (3) for closing the piston.