WO1991005164A1

WO1991005164A1 - Piston pump and piston pump and motor assembly

Info

Publication number: WO1991005164A1
Application number: PCT/BR1990/000018
Authority: WO
Inventors: José Maurício NASCIMENTO PACHECO; Claudio Nascimento Pacheco
Original assignee: Nascimento Pacheco Jose Mauric; Claudio Nascimento Pacheco
Priority date: 1989-10-03
Filing date: 1990-10-04
Publication date: 1991-04-18
Also published as: JPH04502053A; BR8905019A; DE69016638T2; DE69016638D1; EP0446331A1; EP0446331B1; ATE118070T1

Abstract

The present invention refers to a piston pump and motor assembly, of the type comprising a piston pump unit and a piston motor unit coupled in a closed hydraulic circuit, each one of the said pump and motor units having at least one double action piston, and comprising driving means (2, 3, 4, 54, 58, 63) for receiving an input power, at least one first pair of crank arms (21, 81) rotatively driven by the said driving means (2, 3, 4, 54, 58, 63), at least one second pair of crank arms (28, 84) coupled to at least one movable driven shaft (26, 86), at least one pair of crank arms (25, 85) coupling in an intercrossed manner the said first and second pairs of crank arms (21, 28, 81, 84), connecting means (29, 30, 32, 90) coupling the said movable driven shaft (26, 86) to at least one piston (33, 89) of the said pump unit, whereby upon each rotation of the said driving means the said pistons carry out four strokes of hydraulic fluid volumetric displacement, means (42) for directioning the said displaced hydraulic fluid for actuating the said driving means, cam means (9, 10, 66) integral with the said driving means (3, 54, 58, 63) and cam follower means (13, 68, 72) coupled to each piston of the said motor unit, whereby the said pistons of the motor unit cause a hydraulic fluid displacement which is reinforced by the said pistons of the pump unit.

Description

"PISTON PUMP AND PISTON PUMP AND MOTOR ASSEMBLY"

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to hydraulic systems and, wore specifically, to a piston PUMP and to a piston PUMP and Motor assembly particularly suitable to be used in the driving of working units.

Prior Art

Several types and Models of hydraulic PUMPS are widely known from the state of the art, which are used in any and all types of hydraulic systems.

Generally speaking, the pumps can be defined as being one of the basic elements of the hydraulic systems, together with valves. Motors, connections, tubings and others, and their Main objective is to convert electrical, mechanical or even hydraulic energy received from a Motor into dynamic hydraulic energy.

The hydraulic pumps presently known can be divided or classified in five main types or groups, according to its operative principle, namely reciprocating pumps, gear pumps, blade PUMPS, piston pumps and centrifugal pumps.

The reciprocating or alternating movement hydraulic pumps have a Major disadvantage in that the same do not produce a continuous flow of hydraulic energy, which prevents their utilisation in hydraulic systems where a continuous flow is needed.

The gear type hydraulic PUMPS are capable of produc ing continuous flow, with flow rates of approx imately 280

1/min at pressures of 120 kg/cm² . However, the main problem with this type of pump is their low efficiency, since a major part of the received power is used to move its gears and only a small portion of that power is used to generate energy.

The blade type pumps, while being capable of producing flow rates similar to those of the gear pumps with letter efficiency, present the problem of being of comple. construction, with the blades being radially displaceable within a rotor which, in turn, is eccentrically mounted in a housing, turning these pumps fragile and, therefore, more susceptible of failure.

The piston type hydraulic pumps are, up to now, the most resistant and presenting the best efficiency, when the relationship between the power supplied thereto and the amount of dynamic hydraulic energy produced is considered.

These pumps can be of the ax ial type, where the pistons move parallel to the rotor shaft, or of the radial piston type, in which the pistons move inwardly and outwardly with regard to a piston eccentrically mounted within a housing, in a operation similar to those of the blade type pumps.

Due to its rugged construction, the piston PUMPS are capable of providing flow rates up to 1200 1/mιn of p r e ss u r e s in the range of 700 kg/cm², without prejwdice to the safety requirements

Finally, the centrifwgal pumps are used only in hydraulic systems where great volumes of hydraulic fluid need to be displaced at medium or low pressures, due to its low resistance to backup pressures, turning its control more difficult.

Hydraulic motors using hydraulic energy developed by the pumps, both of the rotary and piston types are also widely known from the state of the art.

The rotary hydraulic motors are scarcely used mainly because they can be easily substituted for electric motors . The piston motors, in turn, have an operating principle similar to those of the piston pumps, that is to say, the displacement of a piston causes the displacement of a given volume of hydraulic fluid. Both the pumps and the piston motors can be of the single action type, when the piston produces work only in a single direction of its stroke, or of the double action type, when the piston produces work in both directions of its stroke.

The coupling of hydraulic pumps and Motors is also a technique widely used for Many years. However, up to now, a hydraulic PUMP and motor assembly has not being developed which could be used for driving an independent working uni t, while at the same time being self-supplied by the circulation of a fluid in a closed hydraulic circuit.

SUMMARY OF THE INVENTION

One objective of the present invention is to provide a hydraulic pump unit, more particularly a piston pump, which is capable of developing in a closed hydraulic circuit an output power greater than the power supplied thereto.

Another objective of the present invention is to provide a hydraulic PUMP and motor assembly, more particularly a piston pump and motor, connected in a closed hydraulic circuit, in which the power developed by the said pump unit sufficient for driving the said motor, in order to assure its own driving, while still generating an output power for driving an independent working unit.

According to the present invention, these objectives are achieved by the provision of a piston pump of the type comprising at least a double action piston, the said pump having driving means for receiving an input power, a first pair of crank arms rotatively driven by the said driving means, a second pair of crank arms coupled to a movable driven shaft, a pair of crank arms coupling, in an intercrossed Manner, the said first and second pairs of crank arms and connection means coupling the said movable driven shaft to the said piston, whereby upon each rotation of the said driving means the piston carries out four strokes of hydraulic fluid volumetric displacement.

Still in accordance with the present invention, these objectives are achieved by the provision of a piston pump and Motor assembly of the type comprising at least a dowble action piston, the said assembly having a pump unit with driving weans for receiving an input power, a first pair of crank arms rotatively driven by the said driving means, a second pair of crank arms coupled to a movable driven shaft, a pair of crank arms coupling in an intercrossed manner the said crank arms of the first and second pairs of arms, connecting means coupling the said movable driven shaft to the piston of said pump, whereby upon each rotation of the said driving weans, the pump piston carries out four strokes of hydraulic fluid volumetric displacement, means for directing the hydrau- lic fluid displaced by the said pump piston for driving the said driving means and a motor unit having cam means integral with the said driving means and cam follower means coupled to the pistons of the said motor, whereby the said motor pistons cause a hydraulic fluid volumetric displacement which is am- plified by the pistons of the said pump unit.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described in greater details in a non-limitative and exemplified manner making reference to its presently preferred embodiment, which is illus- trated in the attached drawings- wherein:

Figure 1 is a cross-section view of a piston pump and motor assembly in accordance with the present invention;

Figure 2 is cross-section view of the motor unit of the assembly illustrated in figure 1, taken along line II-II in f i gure 1 ;

Figure 3 is a cross-section view of the motor unit shown in figure 1, taken along line I I I-III of figure 1;

Figure 4 is a cross-section view of the pump unit of the assembly shown in figure 1, taken along line IV-IV of fig- ure 1;

Figure 5 is a cross-section view of a second embodiment of the piston pump and motor assembly in accordance with the invention;

Figure 6 is a cross-section view of the motor unit of the assembly shown in figure 5, taken along line VI-VI of figure 5;

Figure 7 is cross-section view of the pump unit of the assembly shown in figure 5, taken along line VII-VII of figure 5; Figure 8 is a cross-sect ion view of another embodiment of the PUMP unit shown in figure 7;

Figure 9 is a cross-sect ion view of the pump unit shown in figure 8, taken along line IX-IX of figure 8; and

Figure 10 is a schematic view of the basic hydraul ic circuit of the piston pump and motor assembly of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Making reference to the drawings, a piston pump and a piston PUMP and motor assembly in according with the present invention are illustrated in the attached drawings, which a intended to illustrate the presently preferred embodiments the invention and are not intended to limit its scope.

Figure 1 is a cross-section view of a piston pump and motor assembly in accordance with the present invention comprising a box or housing 1 having a suitable shape, driven by a pulley 2 fixed to a driving shaft 3 by Means of a key 4 or the like.

The said driving shaft 3 freely rotates within the said box 1 supported on ball bearings 5 and a retainer 6 is placed in a housing 7 of the said box 1, adjacent to the pulley 2, so as to prevent any hydraulic fluid leakage there- from. Additionally, the said shaft is also provided with a counterbalance wheel 8 near to one of its ends.

The counterbalance wheel 8 and two cams 9, 10, intended to drive the driving pistons 11, 12 of the said motor unit are also secured to the said driving shaft 3 by means of the said keys 4, as it can be seen from the cross-section illustration showing details of its connecting portions to the said shaft 3 and also from figures 2 and 3.

The rotational movement of the said cams 9, 10 i s converted into alternate movement of the said pistons 11, by cam follower rollers 13 fixed to the lower ends of the said pistons 11, 12, by means of U shaped fixing elements 14, which legs are formed with transpassing rolls within which are received the central shafts 16 of the ball bearings 17, around which the said rollers 13 freely rotate.

The said cams 9 and 10 are preferably discs having a contour defined by the Archimedes spiral curve equation, so that its rotational movement when converted into an alternate movement of the said pistons 11, 12, causes this alternate movement to be uniform in both direction; so as to prevent pressure peaks in the hydraulic fluid being pumped.

Referring now more particularly to figure 4, the hydrawlic pump unit for fluids of the pump and motor a ssembly is accordance with the present invention is shown driven by the said driving shaft 3 through a gear 18 connected thereto b y a key 4, which engages another gear 19 fixed to a stationary driven shaft 20 having two crank arms 21 connected thereto by means of keys 4.

The said shaft 20 freely rotates supportpc by ball bearings 22 received in support columns 23 and each one of the said crank arms 21 is provided with a ball bearing 24 in its distal end for rotational coupling with a pair of intercrossed Piston rods 25 which transmit the rotation movement of the said stationary driven shaft 20 to an upper driver. shaft 26 movable by means of a similar assembly or ball bearings 27 provided in the distal ends of the crank arms 28 secured to the said Movable driven shaft 26 by Means of keys 4.

The said movable upper driven shaft 26 freely rotates supported by bearings 29 secured to a fixing element 30. An anti-backup mechanism 31 such as a sprocket is coupled to the said movable upper driven shaft 26, so as to prevent rotation thereof in a direction contrary to a desired one.

The inter-crossed disposition of the piston rods 25 causes each rotation of the driving shaft 3, or of the stationary driven shaft 20 be transformed in two vertical displacements of the movable driven shaft 26, and accordingly, of the shaft 32 to which the fixing element 30 is secured and which has the piston 33 in its end, whereby this piston 33 moves four times within th e c y l i n d e r 34 up o n e a c h r o t a t i o n o f th e dr i v i n g sh af t 3 , while in a normal cranl, arm system this piston would only move twice.

This allows the piston 33 to carry out a hydraulic fluid volumetric displacement within the cylinder 34 which doubles the dynamic hydraulic energy of the system, allowing the piston pump and motor assemble not only to seH supply but also to generate an output power for a separate operatin unit,

Since this piston 33 is of the double action type, unidirectional valves 3 5, 36, 37, 38 are disposed in the ends of the cylinder 34, connecting the fluid supply lines 39 and the fluid discharge lines 40 thereto.

Referring again to figure 1, the piston pump and motor assembly according to the present invention is shown comprising a rotary directional valve 41, of high flow rate and speed, having a box 42 provided with inlet/outlet openings for hydraulic fluid 43 within which is a conversion and distribution bushing 44 f o r m e d with four openings 45, which area corresponds to the area of each inlet/outlet opening 43, so as to prevent interruption of the hydraulic fluid flow due to clogging.

A distribution rotor 46 is disposed within the said bushing 44 so as to control the distribution of the hydraulic fluid in the system, which rotor is driven by Means of a gear 47 coupled thereto through a fine adjust Means 48, which will not be described herein in greater details since it is not part of the present invention.

Two bearings 49 support the said distribution rotor 46 within the said bushing 44, so that the motor can freely rotate when driven by the said gear 47 which, in turn, is directly driven by a gear 50 secured to the said driving shaft 3 by means of a key 4.

In this manner, the said rotary directional valve 41 permits the circulation of the hydraulic fluid from a pressure accumulator 51 to a pressurized reservoir 52 in a closed hydraulic circuit as represented by figure 10, so that the power or torque supplied to the piston pump and motor assembly of the present invention through the pulley 2 is doubled serving not only to assure the continuous working of the pump and motor assembly but also to generate an output power, which can be used to actuate another working unit.

Figures 5, 6 and 7 illustrate a second embodiment of the present invention, in which the piston pump and motor assembly according to the invention is shown having pairs of Pistons.

A box 53, having a suitable shape receives a driving shaft 54 which freely rotates supported by bearings 55 secured to the said box, with a retainer 56 being disposed in a housing 57 of the said box to prevent any hydraulic fluid leakage. Again, a pulley 58 is secured by means of a key 59 to the end of the shaft 54, for transmitting/receiving a torque.

A gear 60 and a counterbalance wheel 61 are fixed to the said shaft 54 by means of a key 59, which gear 60 engages a second gear 62 connected to a second shaft 63 parallel to the said driving shaft 54 by means of a key 59, which simultaneously fixes a second counterbalance wheel 64.

The said second shaft 53 freely rotates within the said box 53 supported on bearings 65 and projects into the pump compartment of the assembly, for driving the pump mechanism as it will be described in greater details below.

Each one of the said shafts 54, 63 has a cam disc 66 attached thereto by means of keys 67.

As above mentioned, the said cams 66 have profiles defined according to the Archimeds spiral curve, so that the transformation of the rotational movement of the shafts in a alternate movement of the pistons results in a uniform and constant displacement for avoiding pressure peaks of the hydraulic fluid.

Two cam follower rollers 68 interconnected by a rocker arm 69 are coupled to a first piston 70 by means of a link shaft 71 for the said rocker arm, while the opposed piston 74 is also driven by two cam follower rollers 72 interconnected by a rocker arm 73 secured to the said piston 74 by Means of a link pin 75.

This constructive disposition of the present invention allows a perfect balance of all the force components, while still providing a greater volumetric displacement due to the utilisation of pairs of pistons.

Within the pump compartment, the said second shaf

63 has a gear 76 attached thereto by means of a key 59, which cooperates with a second gear 77 integral with an intermediate shaft 78 for transmitting a rotational Movement to the gears

79 which cause the pumping system to rotate.

The said gears 79 are fixed to shafts 80, respectively, and each shaft has a first pair of crank arms 81 at tached thereto by means of keys 59. Similar to the preceding embodiment, the shafts 81 rotate on bearings 82 disposed in supports 83.

The distal ends of the crank arms 81 are connected to the distal ends of a second pair of crank arms 84 by means of intercrossed piston rods 85, whereby the shafts 86, which freely rotate supported by bearings 87 having a sprocket system 88 coupled to each one thereof, are vertically displaced upon rotational movement of the shafts 81.

The vertical displacement of the shafts 86 causes a displacement of the pistons 89 coupled thereto by connecting members 90. Thus, the pistons 89 Move four tiMes upon each rotation of the shafts 81, doubling the hydraulic fluid volumetric displacement in the system.

Again, in order that the pistons function as double action pistons, admission 91 and discharge 92 unidirectional valves are coupled to the ends of the cylinders 93 within which the pistons move.

Figures 8 and 9 illustrate a second embodiment of the composite pump unit disclosed in figure 7, particularly suitable for direct coupling to a motor assembly. Due to the similarity between this embodiment and the embodiment shown in figure 7, similar reference numbers were given to the same component parts.

Shaft 63 having a gear 76 attached thereto by means of a key 59 within the housing 94, supported by bearings 95 and a retainer 96, received in a housing 97 of the said box 94, serve to prevent any hydraulic fluid leakage out of the box.

Gear 76 directly engages gear 79, without the intermediate gear 77 and respective shaft 78, whereby the rotation of the shaft 63 is transmitted to the shafts 80 by the gears 76 and 79, with the shafts 80 rotating in opposite directions.

As already explained with regard to figures 5, 6 and 7, the shafts 80 rotate supported by bearings 82 provided in columns 83, does defining a synchronized stationary dual assembly by means of gears.

The crank arms 81 fixed to each one of the respective shafts 80 have its distal ends connected to the distal ends of the similar crank arms 84 by Means of the respective pairs of intercrossed piston rods 85, whereby the rotational movement of the stationary shafts 80 is transformed in a vertical displacement movement of the shafts 86 to which are attached the said crank arms 84.

These shafts 86, in turn, rotate supported by bearings 87, with a gear mechanism δδ being used for preventing its displacement in a direction contrary to the desired one, and its alternate movement is transmitted to the cylinders 89 by means of connecting members 90.

According to the present invention, it is provided a piston pump which, upon its volumetric displacement, is capable of doubling the received power and a piston pump and motor assembly which is capable of self-feeding and producing an output power for driving an independent separate operating unit.

Figure 10 schematic illustrates the basic hydraulic system of the present invention, comprising, besides the above-mentioned pressure accumulator 51 and pressurized reser voir 52, a pump unit B, a motor unit M, the said high speed directional valve 42, the conventional hydraulic control valves V and an oil cooler R.

Having described the invention, it is to be understood that the same can suffer several modifications, provided that these modifications do not depart from the spirit and scope of the invention, as defined in the attached claims.

Claims

CLA I MS

1. Piston pump of the type comprising at least a double action piston, characterized by comprising driving means (2,3,4) for receiving an input power, a first pair of crank arms (21) rotatively actuated by the said driving means (2,3,4), a second pair of crank arms (28) coupled to a movable driven shaft (26), a pair of crank arms (25) coupling in a intercrossed manner the said first (21) and second (28) pairs of crank arms, and connecting means (29,30,31) coupling the said movable driving shaft (26) to the said piston (33), whereby upon its rotation of the said driving means the said piston carries out fours strokes of hydraulic fluid volumetric displacement.

2. Piston pump in accordance with claim 1, characterized in that the said driving means comprise a driving shaft (3) having a driving pulley (2) attached thereto by means of a key (4).

3. Piston PUMP in accordance with claim 2, characterized in that the said driving shaft (3) has a gear (18) integral therewith and engaging a second gear (19) integral with a second stationary driven shaft (20).

4. Piston PUMP in accordance with claim 3, characterized in that the said first pair of crank arms (21) is integral with the said stationary driven shaft (20).

5. Piston pump in accordance with claim 4, characterized in that each one of the crank arms (21) of the said first pair is coupled to an end of each crank arm (25) of the said pair.

6. Piston pump in accordance with claim 5, characterized in that the opposite ends of each crank arm (25) are coupled in an intercrossed manner to the said crank arms (28) of the said second pair.

7. Piston PUMP in accordance with claim 6, characterized in that the coupling between the said crank arms (21,28) and the said crank arms (25) comprises bearings (24) therein, integral with a common shaft.

8. Piston pump in accordance with claim 7, charac terized in that the said Movable driven shaft (26) is coupled to the said piston (33) by means of a support member (30) having a pair of bearings (39) on which the said shaft (26) freely rotates.

9. Piston pump in accordance with claim 8, characterized in that the said support member (30) comprises an anti-backup means (31) for securing rotation of the shaft in a single direction.

10. Piston pump in accordance with claim 9, characterized in that the said anti-backup means (31) comprises a sprocket.

11. Piston pump and motor assembly, of the type comprising a piston pump unit and a piston motor unit coupled in a closed hydraulic circuit, each one of the said pump and motor units having at least one double action piston, characterized by comprising driving means (2,3,4,54,58,63) for receiving an input power, at least a first pair of crank arms (21,81) rotatively driven by the said driving Means (2,3,4,54,58,63), at least a second pair of crank arms (28,84) coupled to at least one movable driven shaft (26,86), at least a pair of crank arms (25,85) coupling in a intercrossed Manner the said first and second pairs of crank arms (21,26,81,84), connecting means (29,30,32,90) coupling th e sa i d Movab l e dr i ven sh a f t ( 26 , 86 ) t o at l e a st on e piston (33,89) of the said PUMP unit, whereby upon rotation of the said driving means the said pistons carry out four strokes of hydraulic fluids volumetric displacement, means (42) for directioning the said displaced hydraulic fluid for actuating the said driving means, cam means (9,10,66) integral with the said driving means (3,54,58,63) and cam follower means (13,68,72) coupled to each piston of the said motor unit, whereby the said pistons of the motor unit cause a hydraulic fluid displacement which is reinforced by the said pistons of the pump unit.

12. Piston pump and motor assembly in accordance with claim 11, characterized in that the said driving Means comprise a driving shaft (3,54) having a pulley (2,58) attached thereto by means of a key (4,59).

13. Piston pump and motor assembly in accordance with claim 12, characterized in that the said driving shaft (3, 54) has a gear (18,60) integral therewith engaging a second gear (19,62,76) integral with a stationary driven shaft (20,63,80).

14. Piston pump and motor assembly in accordance with claim 13, characterized in that the said at least one first pair of crank arms (21,81) is integral with the said stationary shaft (20,80).

15. Piston PUMP and motor assembly in accordance with claim 14, characterized in that each one of the said crank arms (21,81) of the said at least one first pair is coupled to an end of each said crank arm (25,85) of the said at least one pair.

16. Piston PUMP and motor assembly in accordance with claim 15, characterized in that the opposite ends of each crank arm (25,85) are coupled in an intercrossed manner to tthe said crank arms (28,84) of the said at least one second pair.

17. Piston pump and motor assembly in accordance with claim 16, characterized in that the said at least one movable shaft (26,86) is coupled to the said at least one piston (33,89) by means of a support member (30,90) having a pair of bearings (29,87) on which the said shaft (26,86) freely rotates.

18. Piston pump and motor assembly in accordance with claim 17, characterized in that the said support membe

(30,90) comprises an anti-backup Means (31,88) for securing the rotation of the shaft in a single direction.

19. Piston pump and motor assembly in accordance with claim 11, characterized in that the said means for directioning the hydraulic fluid comprises high speed directional valve (42).

20. Piston pump and motor assembly in accordance with claim 11, characterized in that the said cam means comprise cam discs (,10,66).

21. Piston pump and motor assembly in accordance with claim 20, characterized in that the said cam discs (9,10,66) have a contour defined in accordance with the Archimedes spiral curve.

22. Piston pump and motor assembly in accordance with claim 11, characterized in that the said cam follower means comprise rollers (13,68,72).