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WO1996019666A1 - Pump with variable displacement, and high-pressure cleaner including such a pump - Google Patents

Pump with variable displacement, and high-pressure cleaner including such a pump Download PDF

Info

Publication number
WO1996019666A1
WO1996019666A1 PCT/DK1994/000473 DK9400473W WO9619666A1 WO 1996019666 A1 WO1996019666 A1 WO 1996019666A1 DK 9400473 W DK9400473 W DK 9400473W WO 9619666 A1 WO9619666 A1 WO 9619666A1
Authority
WO
WIPO (PCT)
Prior art keywords
disc
oblique
pump
piston
front surface
Prior art date
Application number
PCT/DK1994/000473
Other languages
French (fr)
Inventor
Jørn Gunnar JENSEN
Original Assignee
Kew Industri A/S
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 Kew Industri A/S filed Critical Kew Industri A/S
Priority to AU13096/95A priority Critical patent/AU1309695A/en
Priority to PCT/DK1994/000473 priority patent/WO1996019666A1/en
Publication of WO1996019666A1 publication Critical patent/WO1996019666A1/en

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
    • F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
    • F04B1/26—Control
    • F04B1/28—Control of machines or pumps with stationary cylinders
    • F04B1/29—Control of machines or pumps with stationary cylinders by varying the relative positions of a swash plate and a cylinder block
    • F04B1/295—Control of machines or pumps with stationary cylinders by varying the relative positions of a swash plate and a cylinder block by changing the inclination of the swash plate
    • 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
    • F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
    • F04B1/14—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis having stationary cylinders
    • F04B1/141—Details or component parts
    • F04B1/146—Swash plates; Actuating elements
    • 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
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/12—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00 by varying the length of stroke of the working members
    • F04B49/123—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00 by varying the length of stroke of the working members by changing the eccentricity of one element relative to another element

Definitions

  • the present invention relates to a piston pump of the kind set forth in the preamble of claim l.
  • a pump of the kind referred to above is disclosed in the German published patent application No. 1,918,406.
  • the angle-adjustment means intercon ⁇ necting the two oblique discs are constituted by a pawl- and-ratchet mechanism, operable to carry out a stepwise adjustment by reversing the direction of rotation of the drive shaft.
  • this known pump comprises no facility for continuous automatic regulation of the displacement, such as depending on the delivery pressure.
  • WO 90/03518 discloses an axial-piston hydrostatic machine comprising a pair of inclined discs in axially opposing relationship to control the reciprocating motion of the pistons, one of the discs being rotatable relative to the other under the action of an elastic member which opposes a relative angular shift of the discs tending to modify the displacement, so that the latter is automatically regulated as a func ⁇ tion of the torque applied to the drive shaft, i.e. a function of the delivery pressure, if the machine is a pump.
  • This machine requires two opposing pistons in each cylinder, obviously increasing the cost compared to a machine with only one piston per cylinder, and special measures have to be taken to provide the requisite exter ⁇ nal connections to the cylinders, as they do not possess the customary closed end that may be used for this pur- pose .
  • the input drive torque is applied to the second oblique disc and transferred to the first oblique disc co-operating with the pistons through the elastic member, thus allowing the first disc to yield rotatably under the influence of the tangential component of the reaction force exerted upon the first disc by the pistons, this reaction force obviously being directly proportional to the delivery pressure of the pump.
  • the present invention relates also to a high-pressure cleaner of the kind comprising an axial-piston pump feed ⁇ ing liquid to a cleaning gun ejecting a liquid jet, and according to the invention this cleaner comprises a pump according to any one or any of the claims 1-4.
  • Figure 2 is a view similar to Figure 1, but shows the pump operating with a relatively higher delivery pressure resulting in a correspondingly reduced displacement.
  • the pump shown in Figures 1 and 2 is an axial-piston pump comprising a frame or housing 1 with a number of mutually parallel cylinders 2, of which only two are shown, in which a corresponding number of pistons 3 with protruding end parts 4 are slidingly supported so as to co-operate with the associated cylinder 2 in the normal manner.
  • the pistons 3 are made to reciprocate in the cylinders by a rotating oblique-disc arrangement comprising - a parallel-sided disc 14 with a front surface 15 and a rear surface 16, the end parts 4 being kept in abutment with the front surface 15 by said springs (not shown) , the rear surface 16 thereby being held in abutment with a front surface 5 on a first oblique disc 6, bearing rollers 17 being interposed between the rear sur ⁇ face 16 on the parallel-sided disc 14 and the front surface 5 on the first oblique disc 6, the rear surface 7 of which is held in abutment with a front bearing surface 8 on a second oblique disc 9, bearing rollers 13 being interposed between the rear surface 7 on the first disc 6 and the front surface 8 on the second disc 9.
  • a rotating oblique-disc arrangement comprising - a parallel-sided disc 14 with a front surface 15 and a rear surface 16, the end parts 4 being kept in abutment with the front surface 15 by said springs (not shown)
  • the second disc 9 is adapted to be driven for rotation about an axis 10 by a drive member 11 adapted to be driven by a suitable motor (not shown) .
  • the pistons 3 would reciprocate with a constant stroke, the pump thus having a constant displace ⁇ ment.
  • the first oblique disc 6 is, however, connected to the drive member 11 through an elastic member, in the exemplary embodiment shown in the form of a torsionally elastic rod 12, so that the first oblique disc 6 is able to "give" through a certain angle relative to the second oblique disc 9, provided that a suitable torque is exerted upon it.
  • the requisite tangential force for exerting a torque on the first oblique disc 6 is constituted by the tangential component of the reaction force exerted on the parallel- sided disc 14 by all pistons carrying out a pumping stroke, i.e. working against the delivery pressure of the pump. Obviously, the higher the delivery pressure, the greater the angle, through which the first oblique disc 6 will be rotated in a "lagging" direction towards a position of reduced stroke, such as shown in Figure 2.
  • the cylinders 2 are arranged parallel to the axis of rotation 10 of the drive member 11, but the invention may also be applied to pumps in which the cylinders extend at some acute angle with the axis of rotation.
  • the elastic member connecting the first oblique disc 6 to the second oblique disc 9 is constituted by a torsionally elastic rod 12, but it does also lie within the scope of the invention to use elastic means of a different con ⁇ struction, such as a helical spring coaxial with the drive member 11.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Reciprocating Pumps (AREA)

Abstract

In a pump of the axial-piston or related type, the oblique disc (6), the front surface (5) of which determines the length of the stroke of the pistons (3), comprises a rear surface (7) forming a sharp acute angle with the front surface (5) and co-operating with an oblique front surface (8) on a second oblique disc (9) driven for rotation by a drive member (11), the first disc (6) being rotationally connected to the second disc (9) through an elastic member (12) so as to be able to 'give', when the reaction force from the pistons (3) increases due to increased output pressure, thus causing said front surface (5) to 'tilt' closer to a radial orientation. With this arrangement, automatic displacement control is achieved in a simple and inexpensive manner. The invention also relates to a high-pressure cleaner comprising the pump.

Description

PUMP WITH VARIABLE DISPLACEMENT. AND HIGH-PRESSURE CLEANER INCLUDING SUCH A PUMP
TECHNICAL FIELD The present invention relates to a piston pump of the kind set forth in the preamble of claim l.
BACKGROUND ART
A pump of the kind referred to above is disclosed in the German published patent application No. 1,918,406. In this known pump, the angle-adjustment means intercon¬ necting the two oblique discs are constituted by a pawl- and-ratchet mechanism, operable to carry out a stepwise adjustment by reversing the direction of rotation of the drive shaft. Thus, this known pump comprises no facility for continuous automatic regulation of the displacement, such as depending on the delivery pressure.
The international application No. WO 90/03518 discloses an axial-piston hydrostatic machine comprising a pair of inclined discs in axially opposing relationship to control the reciprocating motion of the pistons, one of the discs being rotatable relative to the other under the action of an elastic member which opposes a relative angular shift of the discs tending to modify the displacement, so that the latter is automatically regulated as a func¬ tion of the torque applied to the drive shaft, i.e. a function of the delivery pressure, if the machine is a pump. This machine requires two opposing pistons in each cylinder, obviously increasing the cost compared to a machine with only one piston per cylinder, and special measures have to be taken to provide the requisite exter¬ nal connections to the cylinders, as they do not possess the customary closed end that may be used for this pur- pose .
DISCLOSURE OF THE INVENTION
It is the object of the present invention to provide a pump of the kind referred to initially, in which features from the two prior art pumps referred to above are com¬ bined to provide a pump of simple construction capable of automatic displacement regulation in dependence of the delivery pressure, and this object is achieved with a pump of the kind referred to initially, that accord¬ ing to the invention is characterized by the features set forth in the characterizing clause of claim 1. With this arrangement, the input drive torque is applied to the second oblique disc and transferred to the first oblique disc co-operating with the pistons through the elastic member, thus allowing the first disc to yield rotatably under the influence of the tangential component of the reaction force exerted upon the first disc by the pistons, this reaction force obviously being directly proportional to the delivery pressure of the pump.
Advantageous embodiments of the pump according to the invention, the effects of which will be evident from the following detailed portion of the present description, are set forth in claims 2-4.
The present invention relates also to a high-pressure cleaner of the kind comprising an axial-piston pump feed¬ ing liquid to a cleaning gun ejecting a liquid jet, and according to the invention this cleaner comprises a pump according to any one or any of the claims 1-4.
BRIEF DESCRIPTION OF THE DRAWINGS
In the following detailed portion of the present descrip- tion, the invention will be explained in more detail with reference to the exemplary embodiment of a piston pump according to the invention diagrammatically shown in the drawings, in which Figure 1 shows the pump in axial section, operating at a relatively low delivery pressure and consequently with a relatively high displacement, and
Figure 2 is a view similar to Figure 1, but shows the pump operating with a relatively higher delivery pressure resulting in a correspondingly reduced displacement.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The pump shown in Figures 1 and 2 is an axial-piston pump comprising a frame or housing 1 with a number of mutually parallel cylinders 2, of which only two are shown, in which a corresponding number of pistons 3 with protruding end parts 4 are slidingly supported so as to co-operate with the associated cylinder 2 in the normal manner.
It should be noted that the drawing only shows the parts of the pump being necessary to explain the invention, and does not show the usual components, such as inlet and outlet valves, bearings and lubricating arrangements etc. Further, elastic members, such as springs, constantly urging the pistons 3 outwardly, are not shown.
The pistons 3 are made to reciprocate in the cylinders by a rotating oblique-disc arrangement comprising - a parallel-sided disc 14 with a front surface 15 and a rear surface 16, the end parts 4 being kept in abutment with the front surface 15 by said springs (not shown) , the rear surface 16 thereby being held in abutment with a front surface 5 on a first oblique disc 6, bearing rollers 17 being interposed between the rear sur¬ face 16 on the parallel-sided disc 14 and the front surface 5 on the first oblique disc 6, the rear surface 7 of which is held in abutment with a front bearing surface 8 on a second oblique disc 9, bearing rollers 13 being interposed between the rear surface 7 on the first disc 6 and the front surface 8 on the second disc 9.
The second disc 9 is adapted to be driven for rotation about an axis 10 by a drive member 11 adapted to be driven by a suitable motor (not shown) .
If the first oblique disc 6 were rigidly secured to the drive member 11, the pistons 3 would reciprocate with a constant stroke, the pump thus having a constant displace¬ ment. The first oblique disc 6 is, however, connected to the drive member 11 through an elastic member, in the exemplary embodiment shown in the form of a torsionally elastic rod 12, so that the first oblique disc 6 is able to "give" through a certain angle relative to the second oblique disc 9, provided that a suitable torque is exerted upon it.
The requisite tangential force for exerting a torque on the first oblique disc 6 is constituted by the tangential component of the reaction force exerted on the parallel- sided disc 14 by all pistons carrying out a pumping stroke, i.e. working against the delivery pressure of the pump. Obviously, the higher the delivery pressure, the greater the angle, through which the first oblique disc 6 will be rotated in a "lagging" direction towards a position of reduced stroke, such as shown in Figure 2. Further turning of the first oblique disc 6 relative to the second oblique disc 9 to a position (not shown) , in which the front surface 15 on the parallel-sided disc 14 lies substantially at right angles to the rotational axis 10, would cause the displacement to be reduced to¬ wards zero.
In the exemplary embodiment shown, the cylinders 2 are arranged parallel to the axis of rotation 10 of the drive member 11, but the invention may also be applied to pumps in which the cylinders extend at some acute angle with the axis of rotation. Also in the embodiment shown, the elastic member connecting the first oblique disc 6 to the second oblique disc 9 is constituted by a torsionally elastic rod 12, but it does also lie within the scope of the invention to use elastic means of a different con¬ struction, such as a helical spring coaxial with the drive member 11. Care should be taken to arrange the connection between the elastic member - in the example shown the torsion rod 12 - and the first oblique disc 6 so as to allow limited angular movement of the latter about a transverse axis relative to the elastic member, if the latter does not in itself allow such movement.
LIST OF PARTS
1 frame/housing
2 cylinder 3 piston
4 end part
5 front bearing surface
6 first oblique disc
7 rear bearing surface 8 front bearing surface
9 second oblique disc
10 axis
11 disc member
12 torsion(ally elastic) rod 13 bearing rollers
14 third disc / parallel-sided disc
15 front surface
16 rear surface
17 bearing rollers

Claims

C L A I M S
1. Piston pump of the kind comprising a) a frame (1) with, formed therein or secured there- to, b) at least one cylinder (2) and, slidable therein, c) a piston (3) with an end part (4) protruding outside of the associated cylinder and being held slidingly against d) a front bearing surface (5) on a first oblique disc (6) rotatable about an axis (10) of a rotatable drive member (11) and having a rear bearing surface (7) extending at an acute angle with the front bear¬ ing surface (5) and being held by each piston (3) slidingly against e) a front bearing surface (8) on a second oblique disc (9) also rotatable about an axis (10) of a rotatable drive member (11) , f) said first (6) and second (9) oblique discs being relatively angularly adjustable for varying the extent of reciprocating movement of each piston (3) , for this purpose being interconnected by angle- adjustment means (12) , characterized in g) that said second oblique disc (9) is rigidly connected to said drive member (11), and h) that said angle-adjustment means are constituted by an elastic member (12) allowing the first oblique disc (6) to turn relative to the second oblique disc (9) against a progressively increasing torque.
2. Pump according to claim 1, characterized by a low- friction bearing arrangement (13) between the first (6) and the second (9) oblique discs.
Pump according to claim 1 or 2, characterized by a third disc (14) with mutually parallel front and rear surfaces, of which the front surface (15) is engaged by the protruding end part (4) of each piston (3) , and the rear surface (16) bears against the front surface (5) on the first oblique disc (6) , preferably through a low-friction bearing arrangement (17) .
4. Pump according to any one or any of the claims 1-3, characterized in that the elastic member is con¬ stituted by a torsionally elastic rod (12) with each of its ends secured to one of said two oblique discs (6,9) .
5. High-pressure cleaner of the kind comprising an axial-piston pump feeding liquid to a cleaning gun ejecting a liquid jet, characterized in that said pump is a pump according to any one or any of the claims 1-4.
PCT/DK1994/000473 1994-12-19 1994-12-19 Pump with variable displacement, and high-pressure cleaner including such a pump WO1996019666A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU13096/95A AU1309695A (en) 1994-12-19 1994-12-19 13115with variable displacement, and high-pressure cleaner including such a pump
PCT/DK1994/000473 WO1996019666A1 (en) 1994-12-19 1994-12-19 Pump with variable displacement, and high-pressure cleaner including such a pump

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/DK1994/000473 WO1996019666A1 (en) 1994-12-19 1994-12-19 Pump with variable displacement, and high-pressure cleaner including such a pump

Publications (1)

Publication Number Publication Date
WO1996019666A1 true WO1996019666A1 (en) 1996-06-27

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DK1994/000473 WO1996019666A1 (en) 1994-12-19 1994-12-19 Pump with variable displacement, and high-pressure cleaner including such a pump

Country Status (2)

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AU (1) AU1309695A (en)
WO (1) WO1996019666A1 (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997029281A1 (en) * 1996-02-08 1997-08-14 Whitemoss, Inc. Method and apparatus for controlling axial pump
GB2329940A (en) * 1997-06-09 1999-04-07 Saphirwerk Ind Prod Apparatus for the metered delivery of fluids
US5979294A (en) * 1996-02-08 1999-11-09 Whitemoss, Inc. Method and apparatus for controlling axial pump
WO2003087579A1 (en) * 2002-04-16 2003-10-23 Ernst Beck Drive device for a machine in particular a pump

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3486454A (en) * 1968-04-16 1969-12-30 Borg Warner Piston pump with remote control of displacement
WO1990003518A1 (en) * 1988-09-27 1990-04-05 Gualtiero Maurer Axial piston hydrostatic machine with variable displacement

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3486454A (en) * 1968-04-16 1969-12-30 Borg Warner Piston pump with remote control of displacement
WO1990003518A1 (en) * 1988-09-27 1990-04-05 Gualtiero Maurer Axial piston hydrostatic machine with variable displacement

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997029281A1 (en) * 1996-02-08 1997-08-14 Whitemoss, Inc. Method and apparatus for controlling axial pump
US5979294A (en) * 1996-02-08 1999-11-09 Whitemoss, Inc. Method and apparatus for controlling axial pump
GB2329940A (en) * 1997-06-09 1999-04-07 Saphirwerk Ind Prod Apparatus for the metered delivery of fluids
GB2329940B (en) * 1997-06-09 2001-06-06 Saphirwerk Ind Prod Apparatus for the metered delivery of fluids
WO2003087579A1 (en) * 2002-04-16 2003-10-23 Ernst Beck Drive device for a machine in particular a pump

Also Published As

Publication number Publication date
AU1309695A (en) 1996-07-10

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