GB2064700A - Ball piston - Google Patents

Ball piston Download PDF

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Publication number
GB2064700A
GB2064700A GB8029613A GB8029613A GB2064700A GB 2064700 A GB2064700 A GB 2064700A GB 8029613 A GB8029613 A GB 8029613A GB 8029613 A GB8029613 A GB 8029613A GB 2064700 A GB2064700 A GB 2064700A
Authority
GB
United Kingdom
Prior art keywords
ball
seating
piston
base member
pistons
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB8029613A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
LECO HYDRAULICS Ltd
Original Assignee
LECO HYDRAULICS Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by LECO HYDRAULICS Ltd filed Critical LECO HYDRAULICS Ltd
Priority to GB8029613A priority Critical patent/GB2064700A/en
Publication of GB2064700A publication Critical patent/GB2064700A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
    • F04B1/04—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinders in star- or fan-arrangement
    • F04B1/0404—Details or component parts
    • F04B1/0408—Pistons
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16J—PISTONS; CYLINDERS; SEALINGS
    • F16J1/00—Pistons; Trunk pistons; Plungers
    • F16J1/10—Connection to driving members

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Details Of Reciprocating Pumps (AREA)

Abstract

Ball piston apparatus comprises a plastics seating (9) for a ball (6), a locking member (8) engaging with the seating (9) and a sleeve (7) which has a threaded connection with the locking member (9) and has an internal lip (11), the latter retaining the ball (6) on the seating (9) and prevents cavitation in the apparatus due to undesired movements of the ball (6). <IMAGE>

Description

SPECIFICATION Pistons for ball piston apparatus This invention relates to pistons 'for ball piston apparatus.
Ball piston motors incorporate a pluraiity of ball pistons slidably located in cylinders disposed radially in a cylinder block rotatable around a centrai feed block on which is mounted a cam. The introduction of hydraulic fluid to the cylinders causes the pistons to reciprocate and react against the cam to transmit rotary motion to the cylinder block and generate a power output. Such machines can also be used as pumps by rotating the cylinder block relative to the cam, thereby driving the pistons and serving to pump hydraulic fluid through the cylinders. In some cases the balls incorporated in the pistons can be repiaced by roilers, but for ease of description reference will be made hereinafter to ball pistons, it being understood that the invention is also applicable to roller pistons.
One of the problems encountered in hydraulic systems incorporating ball piston machines is "cavitation". This arises under various operating conditions which permit the balls which form parts of the pistons to rise from their seatings and subsequently be forced back by fluid pressure. A further situation in which this condition can arise is when machinery incorporating ball piston motors is driven at high speed so that the motors are free wheeling. Free movement of the balls in this way can result in severe damage and failure of the seatings on which the balls locate and it is an object of the present invention to obviate or mitigate this disadvantage.
The invention provides a piston for ball piston apparatus, said piston comprising a base member providing a seating for a ball, and a sleeve member surrounding the ball and engaging with the base member, the sleeve member having an internal lip at an end remote from the base member so as to retain the ball on the seating.
Preferably the base member has an externally threaded surface and the sleeve member has an internally threaded surface releasably engaging therewith. The base member may comprise a locking member having the externally threaded surface and a seating member, a surface of the latter remote from the locking member being of part spherical configuration to define the seating for the ball.
An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is an elevation of a piston for a ball piston machine according to the invention; and Figure 2 is a vertical cross-section on the line ll-ll in Fig. 1.
Referring to the drawing, the piston includes a base member 5 defining a seating for a ball 6 which is surrounded by a sleeve member 7 detachably connected to the base member. The base member consists of a lower locking portion 8 and an upper seating member 9, the upper surface of the latter being of part spherical shape to conform to the surface of the ball 6. The locking member 8 includes an enlarged diameter end portion 10 and the remainder of the external circumference is provided with screw threads which mate with internal screw threads on the sleeve member 7.
At its upper or outer end the sleeve member 7 is provided with an inturned lip 11 which forms an opening 1 2 having a diameter slightly less than the diameter of the ball 6.
The lip 11 therefore serves to retain the ball 6 within the sleeve 7. The length of the sleeve 7 is such that when it is screwed fully home on the base member 5 the ball 6 is retained against bodily movement between the seating 9 and the lip 11 but is free to rotate. The lower or inner end of the sleeve member 7 abuts the end portion 10 of the locking member 8, the outer surfaces of the end portion 10 and the sleeve member 7 being flush with one another. A central bore 1 3 is formed through the base member 5 and the sealing member 9 for the purpose of lubrication of the ball and seating.
It will be seen that the ball 6 is a close fit within the cavity formed by the seating member 9 and the lip 11 on the sleeve member 7 so that the ball is restrained against bodily movement but is free to rotate. The ball cannot therefore be moved to and from the seating member 9 irrespective of operating conditions and hence ball freedom is reduced or eliminated. The construction is also simple and robust and does not incorporate any detachabie parts which might become loose during operation of the machine and cause damage.
Various modifications may be made without departing from the invention. For example, while the seating is preferably made of a plastics material and the other components of cast iron, different materials could be used if desired in appropriate circumstances. The invention may also be applied to pistons of various different shapes and sizes.
1. A piston for ball piston apparatus, said piston comprising a base member providing a seating for a ball, and a sleeve member surrounding the ball and engaging with the base member, the sleeve member having an internal lip at an end remote from the base member so as to retain the ball on the seating.
2. A piston according to claim 1, wherein the base member has an externally threaded
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Pistons for ball piston apparatus This invention relates to pistons 'for ball piston apparatus. Ball piston motors incorporate a pluraiity of ball pistons slidably located in cylinders disposed radially in a cylinder block rotatable around a centrai feed block on which is mounted a cam. The introduction of hydraulic fluid to the cylinders causes the pistons to reciprocate and react against the cam to transmit rotary motion to the cylinder block and generate a power output. Such machines can also be used as pumps by rotating the cylinder block relative to the cam, thereby driving the pistons and serving to pump hydraulic fluid through the cylinders. In some cases the balls incorporated in the pistons can be repiaced by roilers, but for ease of description reference will be made hereinafter to ball pistons, it being understood that the invention is also applicable to roller pistons. One of the problems encountered in hydraulic systems incorporating ball piston machines is "cavitation". This arises under various operating conditions which permit the balls which form parts of the pistons to rise from their seatings and subsequently be forced back by fluid pressure. A further situation in which this condition can arise is when machinery incorporating ball piston motors is driven at high speed so that the motors are free wheeling. Free movement of the balls in this way can result in severe damage and failure of the seatings on which the balls locate and it is an object of the present invention to obviate or mitigate this disadvantage. The invention provides a piston for ball piston apparatus, said piston comprising a base member providing a seating for a ball, and a sleeve member surrounding the ball and engaging with the base member, the sleeve member having an internal lip at an end remote from the base member so as to retain the ball on the seating. Preferably the base member has an externally threaded surface and the sleeve member has an internally threaded surface releasably engaging therewith. The base member may comprise a locking member having the externally threaded surface and a seating member, a surface of the latter remote from the locking member being of part spherical configuration to define the seating for the ball. An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is an elevation of a piston for a ball piston machine according to the invention; and Figure 2 is a vertical cross-section on the line ll-ll in Fig. 1. Referring to the drawing, the piston includes a base member 5 defining a seating for a ball 6 which is surrounded by a sleeve member 7 detachably connected to the base member. The base member consists of a lower locking portion 8 and an upper seating member 9, the upper surface of the latter being of part spherical shape to conform to the surface of the ball 6. The locking member 8 includes an enlarged diameter end portion 10 and the remainder of the external circumference is provided with screw threads which mate with internal screw threads on the sleeve member 7. At its upper or outer end the sleeve member 7 is provided with an inturned lip 11 which forms an opening 1 2 having a diameter slightly less than the diameter of the ball 6. The lip 11 therefore serves to retain the ball 6 within the sleeve 7. The length of the sleeve 7 is such that when it is screwed fully home on the base member 5 the ball 6 is retained against bodily movement between the seating 9 and the lip 11 but is free to rotate. The lower or inner end of the sleeve member 7 abuts the end portion 10 of the locking member 8, the outer surfaces of the end portion 10 and the sleeve member 7 being flush with one another. A central bore 1 3 is formed through the base member 5 and the sealing member 9 for the purpose of lubrication of the ball and seating. It will be seen that the ball 6 is a close fit within the cavity formed by the seating member 9 and the lip 11 on the sleeve member 7 so that the ball is restrained against bodily movement but is free to rotate. The ball cannot therefore be moved to and from the seating member 9 irrespective of operating conditions and hence ball freedom is reduced or eliminated. The construction is also simple and robust and does not incorporate any detachabie parts which might become loose during operation of the machine and cause damage. Various modifications may be made without departing from the invention. For example, while the seating is preferably made of a plastics material and the other components of cast iron, different materials could be used if desired in appropriate circumstances. The invention may also be applied to pistons of various different shapes and sizes. CLAIMS
1. A piston for ball piston apparatus, said piston comprising a base member providing a seating for a ball, and a sleeve member surrounding the ball and engaging with the base member, the sleeve member having an internal lip at an end remote from the base member so as to retain the ball on the seating.
2. A piston according to claim 1, wherein the base member has an externally threaded surface and the sleeve member has an internally threaded surface releasably engaging therewith.
3. A piston according to claim 2, wherein the base member comprises a locking member having the externally threaded surface and a seating member, a surface of the latter remote from the locking member being of part spherical configuration to define the seating for the ball.
4. A piston according to any of the preceding claims, wherein the seating is formed of a plastics material.
5. A piston for ball piston apparatus substantially as hereinbefore described with reference to the accompanying drawing.
6. Any novel subject matter or combination including novel subject matter herein disclosed, whether or not within the scope of or relating to the same invention as any of the preceding claims.
GB8029613A 1979-09-13 1980-09-12 Ball piston Withdrawn GB2064700A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8029613A GB2064700A (en) 1979-09-13 1980-09-12 Ball piston

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB7931780 1979-09-13
GB8029613A GB2064700A (en) 1979-09-13 1980-09-12 Ball piston

Publications (1)

Publication Number Publication Date
GB2064700A true GB2064700A (en) 1981-06-17

Family

ID=26272865

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8029613A Withdrawn GB2064700A (en) 1979-09-13 1980-09-12 Ball piston

Country Status (1)

Country Link
GB (1) GB2064700A (en)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1987003227A1 (en) * 1985-11-22 1987-06-04 Davy Mckee (Poole) Limited Rolling mill
WO1998014722A1 (en) * 1996-10-02 1998-04-09 Jurij Manfreda A piston assembly of a hydraulic radial piston-type machine
FR2808067A1 (en) * 2000-04-21 2001-10-26 Bio Merieux Piston mechanism e.g. for diagnostic apparatus has intermediate element(s) to actuate piston(s) and recuperator e.g. magnet
WO2001081727A1 (en) 2000-04-21 2001-11-01 Jurij Manfreda Piston assembly for a radial piston hydraulic motor
FR2899285A1 (en) * 2006-03-31 2007-10-05 Poclain Hydraulics Ind Soc Par Piton for radial piston hydraulic engine, has circular base adapting shape of cylinder in which piston slides, where base is close to bottom of cylinder when piston is installed in cylinder of radial piston engine
WO2012059315A1 (en) * 2010-11-05 2012-05-10 Robert Bosch Gmbh Pump, in particular high-pressure fuel pump
WO2016097230A1 (en) * 2014-12-17 2016-06-23 Poclain Hydraulics Industrie Integral roller piston and associated method

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1987003227A1 (en) * 1985-11-22 1987-06-04 Davy Mckee (Poole) Limited Rolling mill
US4813259A (en) * 1985-11-22 1989-03-21 Davy Mckee (Poole) Limited Rolling mill
WO1998014722A1 (en) * 1996-10-02 1998-04-09 Jurij Manfreda A piston assembly of a hydraulic radial piston-type machine
US6276261B1 (en) 1996-10-02 2001-08-21 Jurij Manfreda Piston assembly of a hydraulic radial piston-type machine
US6854376B2 (en) 2000-04-21 2005-02-15 Biomerieux S.A. Device for actuating a least piston and method for detecting failure in a device
WO2001080999A1 (en) * 2000-04-21 2001-11-01 Biomerieux S.A. Device for actuating at least a piston and method for detecting failure in a device
WO2001081727A1 (en) 2000-04-21 2001-11-01 Jurij Manfreda Piston assembly for a radial piston hydraulic motor
US6834575B2 (en) 2000-04-21 2004-12-28 Jurij Manfreda Piston assembly for a radial piston hydraulic motor
FR2808067A1 (en) * 2000-04-21 2001-10-26 Bio Merieux Piston mechanism e.g. for diagnostic apparatus has intermediate element(s) to actuate piston(s) and recuperator e.g. magnet
US8522432B2 (en) 2006-03-31 2013-09-03 Poclain Hydraulics Industrie Method of manufacturing a piston for a hydraulic motor having radial pistons
WO2007113443A1 (en) * 2006-03-31 2007-10-11 Poclain Hydraulics Industrie Piston for a radial piston hydraulic engine and method for making same
US8281707B2 (en) 2006-03-31 2012-10-09 Poclain Hydraulics Industrie Piston for a hydraulic motor having radial pistons, and a method of manufacturing such a piston
FR2899285A1 (en) * 2006-03-31 2007-10-05 Poclain Hydraulics Ind Soc Par Piton for radial piston hydraulic engine, has circular base adapting shape of cylinder in which piston slides, where base is close to bottom of cylinder when piston is installed in cylinder of radial piston engine
WO2012059315A1 (en) * 2010-11-05 2012-05-10 Robert Bosch Gmbh Pump, in particular high-pressure fuel pump
CN103201499A (en) * 2010-11-05 2013-07-10 罗伯特·博世有限公司 Pump, in particular high-pressure fuel pump
CN103201499B (en) * 2010-11-05 2016-10-05 罗伯特·博世有限公司 Pump
WO2016097230A1 (en) * 2014-12-17 2016-06-23 Poclain Hydraulics Industrie Integral roller piston and associated method
FR3030665A1 (en) * 2014-12-17 2016-06-24 Poclain Hydraulics Ind MONOBLOCK ROLLER PISTON AND METHOD THEREOF

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)