FR2805313A1 - PNEUMATICALLY DRIVEN HYDRAULIC PUMP - Google Patents

Abstract

The invention relates to a hydraulic pump (1) comprising a pneumatic piston (6) located in a cylinder-shaped housing (2) and controlling pilot valves (4, 5), and a hydraulic piston (7) connected in a connection. force to the piston (6), and a base (3) housing the valves and integral with the housing (2) in stepped bores (12, 13) of a valve base (3) and a cover (11) , and a control box (25) is laterally connected to the valve base (3) and includes a control piston (48) moving a sliding shoe (60) diverting working air to chambers (34, 36) around the valve. piston (6). Application to hydraulic pumps.

Description

PNEUMATICALLY DRIVEN HYDRAULIC PUMP A pneumatically driven hydraulic pump of the type in question known for example from German document DE 26 26 954 C2 is part of the technique. It has asserted itself in practice because of its capacity for multiple use.

Such a hydraulic pump comprises, in a reference version, a pneumatic piston moving back and forth in a cylinder-shaped housing, as well as a hydraulic piston connected by a force connection to the pneumatic piston. This hydraulic piston is connected via a suction valve to a suction pipe and via a discharge valve to a pressure pipe. Due to the reciprocating movement of the pneumatic piston and therefore also of the hydraulic piston, the latter sucks hydraulic fluid and then transfers this hydraulic fluid under pressure.

The reciprocating movement of the pneumatic piston is achieved by means of a partially hollow tone plunger as well as at least one pilot valve, which is actuated by the pneumatic piston ensuring that the piston plunger is moved from one end position to the other end position. The piston plunger has two active surfaces having different sizes at the front. The smallest on the active face is permanently charged by the working air while the extended active surface is charged by the working air via a pilot valve, when the piston plunger is moved in the other direction. For the transfer of the working air into the working chambers on both sides of the pneumatic piston and for the discharge of the outgoing air, the piston plunger is guided in a stepped sleeve, which must be manufactured in a way expensive, has transverse holes and circumferential grooves and has several circumferential sealing rings arranged at a distance from each other. Apart from the complicated bushing, this provides a special feature in the known case, in that the sealing rings permanently cross the mouths of the bores in the bushing and therefore are subject to high wear. Likewise, the bush must be supported in a leaktight manner in the bore, which receives it, of the hydraulic housing.

From the state of the art, the invention aims to be able to manufacture the hydraulic pump known from the point of view of mass production and modular manufacture with lower expenditure.

This problem is solved in accordance with the invention by means of a pneumatically driven hydraulic pump, which comprises a pneumatic piston, which is movable in a cylinder-shaped housing of plastic material comprising a valve bottom which is integral, and in the two end positions, control of the pilot valves, and a hydraulic piston, which is connected in a force connection to the pneumatic piston and is connected via a suction valve to a suction pipe and via a pressure valve to a pressure line, characterized in that a 1st pilot valve is provided in a stepped bore inside the valve bottom and the 2nd pilot valve is provided in a stepped hole formed in a removable plastic end cap, which closes the cylinder-shaped housing and guides the hydraulic piston and that a control box in plastic material is connected laterally by flange, removably, to the valve bottom, control box in which a control piston having two active front surfaces having different dimensions is movable back and forth by means of 1 working air , using a sliding shoe which has a deflection trough, which has the effect that on the one hand the working air permanently present in a chamber, which guides the sliding panel, in the control unit can be sent, via channels, formed in the valve bottom, in the wall and in the end cap of the cylinder-shaped housing, alternately to a working chamber or to the other on both sides of the pneumatic piston as well as at the level of the sealing bodies of the pilot valves, and on the other hand the air leaving the working chambers can be sent to the atmosphere via the deflection trough ion located in the sliding shoe.

An essential point of view resides in the fact that the cylinder-shaped housing fitted with the valve bottom formed integrally on this housing, the end cap detachably associated with the cylinder-shaped housing and also the housing control for the control piston and the slide are now made of plastic, in particular polyoxymethylene. Preferably these elements are arranged in the form of injection molded parts. This guarantees inexpensive mass production for all sizes and for all types.

On the other hand, it is important that the role of a flat slide has been assigned to the sliding shoe. Likewise, the latter can be produced in the form of an injection molded plastic part. Depending on its position in the control box, it guarantees the sending of working air into one or other of the working chambers on both sides of the pneumatic piston and, due to the presence of the deflection trough formed in this sliding shoe, also assumes the transfer of air leaving the working chambers into the atmosphere, in particular by means of a silencer.

The sliding shoe is offset by means of a control piston which is arranged in the control box and comprises two active front surfaces having different surfaces. The smallest on the active face permanently located in the chamber of the control unit, in which the sliding shoe is also located, and is permanently charged by the working air. The control piston can be made of a light metal alloy. I1 is guided in a sealed manner in the control unit. However, the seals do not pass through any drilling mouth, so that they are therefore also not particularly subject to wear. The sliding shoe is forced into the chamber, but slides on an outside face of the valve bottom. Consequently, the operating position of the sliding shoe is guaranteed by the lateral connection by flanges of the control unit to the valve bottom. The sliding shoe generally crosses the mouths of three channels. The latter are arranged in series one behind the other and extend transversely relative to the direction of movement of the pneumatic piston. The two external channels are connected directly to the working chambers located in the cylinder-shaped housing, while the median channel opens into the atmosphere, in particular via a silencer.

The cooperation, according to a force connection and according to a connection by complementary shapes, of the control piston with the sliding shoe is also advantageously improved by the fact in particular that the longitudinal part of the control piston, which projects into the chamber of the control unit and carries the small active surface frontally, has a peripheral recess which is adapted to the length of the sliding shoe configured with a rectangular shape, and extends above the sliding shoe. The recess is in particular formed by a groove formed by turning in the control piston.

According to another characteristic of the invention, the chamber is permanently connected, by means of a bypass channel in the valve bottom, to the stepped bore housing the 1- pilot valve. This guarantees, depending on the position of the pneumatic piston, that the extended active surface of the control piston is loaded via the 1st pilot valve and the channels located in the valve bottom as well as in the valve housing. control, by the working air, and that either the 2nd pilot valve located in the working chamber between the pneumatic piston and the end cap is controlled, or that the 1st pilot valve is pushed back , at its valve lifter, in the working chamber between the pneumatic piston and the valve bottom.

In this regard, according to another characteristic of the invention, it is provided that the stepped bore located in the valve bottom is connected via channels located in the valve bottom and in the control unit to a chamber which guides the longitudinal part of the control piston having the extended active surface and is connected via channels formed in the wall of the cylinder-shaped housing and, in the end cap, to the stepped bore located in this end cap and housing the 2nd pilot valve. The widest active surface is permanently located in a space that is sealed from the chamber, in the control unit. This space can be charged with compressed air via the 1st pilot valve provided in the valve bottom and can be extended into the atmosphere via the 2nd pilot valve located in the end cap. The control piston and the sliding shoe are not fixedly connected to each other, which further simplifies manufacturing and assembly.

In order to be able to evacuate the air from the chamber, from the stepped stage comprising the 2nd pilot valve and channels located between the 1st pilot valve, the chamber and the 2nd pilot valve, according to another characteristic of the invention the stepped bore located in the end cap is connected to the atmosphere via a transverse channel.

According to another characteristic of the invention, the pneumatic piston is connected, in a coaxial orientation relative to the hydraulic piston, according to a force connection to a second hydraulic piston which crosses the valve bottom with possibility of relative displacement and is connected to on the one hand via a suction valve to the suction line and on the other hand via a discharge valve to the pressure line. For the insertion of the second hydraulic piston, it suffices to provide, in the valve bottom, a corresponding guide hole. No other modifications are necessary to make a double-acting hydraulic pump.

According to another characteristic of the invention, it is provided that the pneumatic piston can be moved manually by means of a through linkage with the possibility of relative movement of the valve bottom, against the return force of a spring which is inserted in the working chamber between the pneumatic piston and the end cap, the connection between the chamber and the working chamber situated between the end cap and the pneumatic piston being closed. Consequently, it suffices to insert the spring into the cylinder-shaped housing and to close with a channel plug situated between the chamber and the working chamber adjacent to the end cap. No modification is necessary.

therefore, the hydraulic pump can be operated either with air or manually.

According to another characteristic of the invention, the hand lever associated with the linkage can be rusty worm. In this way it can be certain that during operation with air, the hand lever performs no uncontrolled movement which could possibly cause injury.

Other characteristics and advantages of the present invention will emerge from the description given below, taken with reference to the appended drawings, which ones - FIG. 1 shows, in the form of a schematic vertical longitudinal section, a pneumatically driven hydraulic pump; - Figure 2 shows a side elevational view of the hydraulic pump of Figure 1, seen along arrow II; - Figure 3 shows a horizontal section of the device shown in Figure 2, taken along line III-III; - Figure 4 shows a section of the device shown in Figure 3, taken along the line IV-IV; - Figures 5 to 7 show the devices shown in Figures 1, 3 and 4 in another operating case; FIG. 8 provides a representation in accordance with that of FIG. 1, in the case of another embodiment; FIG. 9 provides a representation in accordance with that of FIG. 5, in the case of another embodiment; and - Figure 10 shows the device shown in Figure 9, in another operating position.

In FIGS. 1, 2 and 5, the reference numeral 1 designates a pneumatically driven hydraulic pump. The hydraulic pump 1 comprises a pneumatic piston 6, which is moved in a plastic cylinder-shaped housing, on which is formed in one piece a valve bottom 3, and control of the pilot valves 4, 5 in both end positions, as well as a hydraulic piston 7 connected by a force connection to the pneumatic piston 6. The pneumatic piston 6 has a circumferential groove 8 in which is inserted a sealing ring 9, which is applied in a sealingly against the interior wall 10 of the cylinder-shaped housing end cap 11 made of plastic material is removably fixed to the end of the cylinder-shaped housing 2, located opposite the bottom 3 with poppies.

Both in the valve bottom 3 and in the end cap 11 are arranged, and this in stepped bores 12, 13, the pilot valves 4 and 5 which each carry a pusher 14 as well as a valve head 15. Seal rings 16 are arranged in the middle longitudinal portion of the valve lifter 14. Other seal rings 17 are located between the valve lifters 14 and the valve heads 15. The pilot valves 4, 5 are loaded by helical pressure springs 18 in the direction of the pneumatic piston 6. They bear on bolts 19 which are screwed into the housings 20 for springs of the stepped holes 12, 13.

Three transverse channels 21, 22, 23 located in series one behind the other are provided in the bottom 3 with valves. The three transverse channels 21, 22, 23 all open into an external face 24 of the valve bottom 3 (see FIGS. 3 and 6), at the level of which is also connected by flanges a control box 25 made of plastic material, which n 'is not shown in detail in Figures 3 and 4. Among the three channels 21, 22, 23, the median channel 22 is connected via a channel 28 to a connector 27 which opens into the front face 26 from the bottom 3 with valves and on which a silencer can be mounted. Among the other two channels 21, 23, the channel 23, which is adjacent to the 1st pilot valve 4, is connected via a longitudinal channel 30 formed in the wall 29 of the cylinder-shaped housing 2 and of channels 31-33 located in the end cap 11 to the working chamber 34 which is adjacent to the end cap 11, for the pneumatic piston 6. third channel 21 located in the bottom 3 with valves0 connected via a channel 35 to the working chamber 36 adjacent to the valve bottom 3.

Furthermore, it can be seen in FIGS. 1 and 5 that the longitudinal part 38, which guides the poppet pusher 14, of the stepped bore 12 in the valve bottom connected via channels 39, 40, 41, 42 located in the bottom 3 with valves, in the wall 29 of the cylinder-shaped casing 2 and in the end cap to the chamber 20 for spring of the stepped bore 13 in the end cap 11. In addition the channel 39 is connects via another channel 43 located in the valve bottom 3 and a channel 44 located in the control box 25, to a chamber 45 located in the control box 25 and in which is movable a longitudinal section 47, provided with a sealing ring 46, a control tone 48 which will be described later in an even more detailed manner.

The longitudinal part 38, which is located between the longitudinal part 37 of the stepped bore 13 located in the end cap 11 and the chamber 20 for spring, is connected to the atmosphere A via a transverse channel 49.

The control piston 48 is guided in a sealed manner, in the control box 25, on the one hand in the chamber 35 mentioned above and on the other hand in a bore 50. For this purpose another sealing ring 51 is inserted in a circumferential groove 52 of the control piston 48. A longitudinal portion 54 control piston 48, which is provided with a recess 53 machined in the lathe, enters a chamber 55 of the control box 25. This chamber 55 is connected in permanently, by means of a connection 56, to a source of working air AL (compressed air The end 57 of the control piston 48 located in the chamber 55 has an active front surface 58, which is less than the surface active 59 provided on the longitudinal part 47 of the control piston 48 in the chamber 45.

The length of the recess 53 on the control piston 48 corresponds to the length of a sliding shoe 60 made of plastic material and configured with a rectangular shape and having a deflection trough 61 which is formed in this shoe. This sliding shoe 60 slides on the external face 24 of the valve bottom 3 and crosses the mouths of the three channels 21, 22, 23.

Figures 1, 4, 5 and 7 also show the chamber 55 is connected via a bypass channel 62 to the chamber 20 for spring of the stepped bore 12 located in the bottom 3 with valves.

The hydraulic piston 7 acts in a T-shaped channel 63 of a high pressure box 65. The latter is connected on the one hand via a suction valve 64 to a suction line 66 for a hydraulic fluid and on the other hand to a discharge valve 67, which is connected to a pressure line 68. The operation of the hydraulic pump 1 visible in FIGS. 1 to 7 is as follows Due to the configuration of the housing com command 25, drive air AL is permanently applied in chamber 55 via the connector 56. As a result, the control piston 48 is moved to the left in the plane of the drawing (FIGS. 3 and 4 ), in which case under the effect of the coupling according to a force connection or a connection by complementary shapes of the control piston 48 to the sliding shoe 60, the latter is jointly driven until it comes to bear against the front face 69 of the room 55. Alo 1s of working air AL coming from the chamber 55 reaches, via the channels 23, 30, 31, 32, 33, in the working chamber 34 adjacent to the end cap 11. Since when the shoe sliding 60 is in this position, the working chamber 36 adjacent to the valve bottom 3 is connected to the atmosphere via the channels 35 and 21, the deflection trough 61 located in the sliding shoe 60 and the channels 22, 28, the pneumatic piston 6 can execute a movement towards the bottom 3 with valves. Simultaneously the working air AL leaving the chamber 55 is applied, via the bypass channel 62, in the spring chamber 20 of the 1st pilot valve 4, which has the effect that the pusher 14 of this valve is moved, in accordance with FIG. 5, and comes into the working chamber 36.

Shortly before the top dead center is reached, the pneumatic piston 6 actuates the plunger 14 of the 1st pilot valve 4 and displaces the latter against the restoring force of the helical pressure spring 18 to the point that the ring seal 17 is moved away from the seat in the stepped hole 12 and the working air AL, which is present in the bypass channel 62, arrives via the longitudinal part 38 of the stepped hole 12, in the channel 39 and, via the channel 43 located in the valve bottom 3 as well as via the channel 44 located in the control box 25, in the space 45 which guides the longitudinal part 47 having the surface active the most extensive 59. Simultaneously the working air AL is applied via the channels 40, 41, 42 in the spring chamber 20 of the 2 nd pilot valve 5. The pusher 14 of this valve is of this actually moved into the room 34 near the end cap 11.

 Since the active surface 59 located in the space 45 is greater than the active surface 58 of the control piston 48 in the chamber 55, the control piston 48 is moved, together with the sliding shoe 60, in the direction of the connector 56 for working air AL, until the rear surface 70 present on the control piston 48 bears against the annular surface 71 of the control box 25 (FIGS. 6 and 7). Under the effect of this displacement, the connection between the connector 56 and the working chamber 34 adjacent to the end cap 11 is interrupted and for this purpose this working chamber 34 connected via the channels 31, 32, 33 , 30, 72, 23 located in the end cap 11, in the wall 29 of the cylinder-shaped shoemaker 2 and in the bottom 3 with poppies, at the deflection trough 61 located in the smoothing shoe 30, then is connected to atmosphere A via channels 22, 28 located in the bottom 3 with valves.

The working air AL then arrives via the channels 21, 35 located in the valve bottom 3, in the working chamber 36 adjacent to the valve bottom 3 and moves the pneumatic piston 6 in the direction of the cap. end 11.

 Since the valve tappet 14 of the pilot valve 4 is no longer in contact with the pneumatic piston 6, the valve tappet 14 is brought by the pressure helical spring 18 to the position shown in the figure 5. The sealing ring 17 is compressed on its seat in the stepped hole 12. The connection between the bypass channel 62 and the channel 39 which is connected to the longitudinal part 38 in the stepped hole 12 in the bottom 3 with valves, is interrupted. Therefore the 'located in channels 39, 40, 41, 42 and 43 and in the chamber 45 as well as in the chamber 20 for spring of the 2nd pilot valve 5 is enclosed.

Shortly before bottom dead center is reached, the pneumatic piston 6 comes into contact with the pusher 14 of the 2nd pilot valve 5 and moves its sealing ring 17 from its sealing position so that now the contained air can relax in the atmosphere through the chamber 20 for spring of the 2nd pilot valve 5 and the longitudinal part 38 through the transverse channel 49.

 Since the chamber 45 in the control unit 35 is therefore connected to the atmosphere A, the working air AL again now moves the control piston 48 and therefore also the smoothing shoe 60 towards the chamber 45, and a new work cycle begins. Due to the gear ratio of the pneumatic piston 6 to the hydraulic piston 7, the hydraulic piston 7 draws hydraulic fluid from the suction line 66 in a direction of movement, via the suction valve 64, so that in the other direction of movement, the hydraulic medium is transferred under high pressure into the pressure line 68 via the pressure valve 67. Under the effect of the oscillatory movement of the pneumatic piston 6 and consequently, from the hydraulic piston 7, there is obtained an almost pulsating drive flow in the pressure pipe 68.

FIG. 8 represents an embodiment of a pneumatically driven hydraulic pump 1a, which corresponds in principle to that which has been explained above with reference to FIGS. 1 to 7. However, another hydraulic piston 7a is also associated with hydraulic piston 7 according to a coaxial association. This other hydraulic piston 7a is also connected according to a force connection to the pneumatic piston 6 and slides through the bottom 3 with valves of the cylinder-shaped housing 2. Likewise the other hydraulic piston acts, like the first hydraulic piston 7, in a T-shaped channel 63 of a high pressure housing 65, and such that it sucks hydraulic fluid from the suction line 66 via a suction valve 64 and then transfers it under high pressure to the pressure line 68 via a discharge valve 67.

 Since, as has been indicated, the embodiment of FIG. 8 coincides with that of FIGS. 1 to 7, we will not give a new explanation of this type of embodiment.

Similarly, the embodiment shown in FIGS. 9 and 10 of a hydraulic pump 1b has, from the point of view of the principle, the arrangement of the hydraulic pump 1 in accordance with FIGS. 1 to 7.

But in addition a manual actuation is super posed this type of realization. The pneumatic piston 6 can be moved manually by means of a trinning 73 which crosses with a possibility of relative movement the bottom 3 with valves, taking into account the restoring force of a helical pressure spring 74 enclosed in the working chamber 34 between the pneumatic piston 6 and the end cap 11. For this purpose the channel 23 located between the chamber 55 in the control box 25 and the channels 30, 31, 32, 33, which lead to the working chamber 34 between the end cap 11 and the pneumatic piston 6, is closed.

The linkage 73 is provided with a hand lever 75. Under the effect of the rotation of the hand lever 75 respectively around 180 ′ around the longitudinal axis 76 of the hydraulic pump 1b, the linkage 73 is displaced back and forth on the stroke of the pneumatic piston 6 in the cylinder-shaped casing 2, so that then, by means of the hydraulic piston 7 connected in a force connection to the pneumatic piston 6, hydraulic fluid is also inserted from a suction line 66 via a suction valve 64 and can be delivered to the pressure line 68 via a discharge valve 67.

If the embodiment of FIGS. 9 and 10 must operate pneumatically, the manual lever 75 is snapped into the position which can be identified by FIG. 10. The channels 30, 31, 32, 33 are permanently closed by the plug 77. The suction stroke is always carried out by spring 74.

The lower chamber 34 of the piston is ventilated via a channel 78. Appropriate filter element 79, which is forced into the ventilation hole, prevents soiling of the lower chamber 34 of the udder.

In the case of operation, which is then again pneumatic, the hand lever 75 is blocked and therefore cannot cause any injury.

Claims (8)

1. Pneumatically driven hydraulic pump (1,1a, 1b), which comprises a pneumatic piston (6), which is movable in a cylinder-shaped housing (2) made of plastic material comprising a bottom (3) with valves which is integral with it, and in the two end positions, controls the pilot valves (4,5), and a hydraulic piston (7), which is connected by a force connection to the pneumatic piston (6) and is connected by the by means of a suction valve (64) to a suction line (66) and by means of a pressure valve (67) to a pressure line (68), characterized in that a 1st pilot valve (4) is provided in a stepped hole (12) inside the valve base (3) and the 2nd pilot valve (5) is provided in a stepped hole (13) formed in a removable plastic end cap (11), which closes the cylinder-shaped housing (2) and guides the hydraulic piston (7) e t that a plastic control box (25) is removably connected laterally by flange to the valve base (3), a control box in which a control piston (48) having two active front surfaces (58 , 59) having different dimensions is movable back and forth by means of the working air (AL), using a sliding shoe (60) which has a deflection trough (61), this which has the effect that on the one hand the working air (AL) permanently present in a chamber (55), which guides the sliding panel (60), in the control unit (25) can be sent, by l 'intermediate channels (21,22 or 23,30,31,32, 33), formed in the bottom (3) with valves, in the wall (29) and in the end cap (11) of the housing cylinder shape (2), alternately to a working chamber (26,34) or to the other on both sides of the pneumatic piston (6) as well as at the level of the sealing bodies (17) of the so pilot upapes (4 5), and on the other hand the air leaving the working chambers (36,34) can be sent to the atmosphere (A) via the deflection trough (61) located in the sliding shoe (60). 2. Hydraulic pump according to claim 1, characterized in that the longitudinal part (54) of the control tone (48), which projects into the chamber (55) of the control box (25) and frontally carries the small active surface (58), has a peripheral recess (53) which is adapted to the length of the sliding shoe (60) configured with a rectangular shape, and extends above the sliding shoe (60). 3. Hydraulic pump according to either of Claims 1 and 2, characterized in that the chamber (55) is permanently connected, by means of a bypass channel (62) located in the bottom ( 3) with valves, with a stepped hole (12) housing the 1st pilot valve (4). 4. Hydraulic pump according to any one of claims 1 to 3, characterized in that the stepped bore (12) located in the bottom (3) with valves is connected via channels (39,43,44) located in the valve bottom (3) and in the control unit (25), to a chamber (45) which guides the longitudinal part (47) of the control piston (48) having the extended active surface (59) and is connected via channels (40,41,42) formed in the wall (29) of the cylinder-shaped housing (2) and, in the end cap (11), with the stepped bore (13) located in this end cap (11) and housing the 2nd pilot valve (5). 5. Hydraulic pump according to any one of claims 1 to 4, characterized in that the stepped bore (13) located in the end cap (11) is connected to the atmosphere (A) via d 'a transverse channel (49). 6. Hydraulic pump according to any one of claims 1 5, characterized in that the pneumatic piston (6) is connected, in a coaxial orientation relative to the hydraulic piston (7), according to a force connection to a second hydraulic piston (7a) which passes through the bottom (3) with valves with the possibility of relative displacement and is connected on the one hand via a suction valve (64) to the suction pipe (66) and on the other hand via a discharge valve (67) to the pressure line (68). 7. Hydraulic pump according to any one of claims 1 to 5, characterized in that the pneumatic piston (10) can be moved manually by the intermediary of a linkage (73) passing through with the possibility of relative movement of the bottom (3 ) with valves, against the return force of a spring (74) which is inserted in the working chamber (34) between the pneumatic piston (6) and the end cap (11), the connection between the chamber (55) and the working chamber (34) located between the end cap (11) and the pneumatic piston (6) being closed. 8. Hydraulic pump according to claim 7, characterized in that a hand lever (75) associated with the linkage (73) is snap-on.