EP1785622B1 - Hydraulic pump - Google Patents

Abstract

Hydraulic pump has control stub (2) which exhibits two control surfaces as well as lies in axial direction beside the rotor (1) and with two control surfaces to its front end, each of which is connected with each piston area, parallel to the axis of rotation and axially running and discharge drilling (3a), is provided at the front side of the rotor. Each line connection of the suction non return valve (5,6) is connected to front and back annular channel (5a,6a) circulating between the housing (12) and the casing of the control pin arranged therein. The front annular surface of the annular channel is formed from an area of the control pin with decreasing radius whereas the front annular surface is limiting the annular channel at its adjacent side close to the front surface of the rotor and the rearward annular surface limiting the annular channel at its side remote to the front surface of the rotor is formed from an area of the housing.

Description

The invention relates to a generic pump according to the preamble of the main claim.

Reversible pumps for various small volume flow applications (e.g., 0.5 l / min), high pressures (e.g., up to 400 bar), and well-defined lifetimes (e.g., 150 hours) are known and of interest. These include, i.a. Pumps for applications in the mobile hydraulics such. Pumps for cab tilting systems.

Today's gear pumps are inexpensive, but do not reach the required pressure level and are not reversible at low flow rates.

Known valve-controlled single-piston pumps are also not reversible and ruled out due to the cost of the reversal by means of a solenoid valve and because of the high pulsation caused by the high noise level. In addition, they have a much higher than required by the market life and are therefore too expensive.

Valve-controlled multi-piston pumps after today Although the state of the art is lower in terms of noise level, it is still more expensive to manufacture due to two additional pump pistons and two additional suction pressure valves. For the reversal, a solenoid valve is still required.

Known slot-controlled radial piston pumps have a rotor with radial pumping pistons and a fixed control pin with two radial control slots. The rotor is rotatably mounted on the control pin. The bearing point must ensure - besides the interception of the pumping forces - at the connection point between the rotor and the control plug oil-tightness. Despite the high production costs, however, a leakage is inevitable due to the design, which has a negative effect on the efficiency. There is also the danger that, due to different sliding pairings, the rotor will jam on the control pin in the event of severe temperature fluctuations. Constant wear in the course of operation can increase the leakage, which has a negative effect on the efficiency and is highly undesirable.

It is also a generic pump according to the preamble of the independent claim known ( US-A-3,028,814 ).

The invention has the object of providing a generic pump easier to manufacture and assembly and thus cheaper so that it remains leaking in operation despite wear.

This object is achieved in a generic pump according to the preamble of the independent main claim according to the invention by its characterizing features.

Depending on the direction of rotation of e.g. From the electric motor driven rotor is therefore according to the teaching of the invention during the first half revolution of the rotor in the one direction of rotation of the individual pump piston from the tank through the opening in the end face of the rotor bore, whenever it covers one of the two control surfaces, hydraulic fluid , eg Oil, sucked through the one suction check valve or the one ring channel while the other closed suction check valve and promoted during the next half turn in the other ring channel. If the direction of rotation changes, the oil is sucked in during the first half revolution via the other suction check valve or the other annular channel with a suction check valve closed at the same time and conveyed into the one annular channel during the next half revolution. The annular channels are configured such that by the hydraulically effective, the end face of the rotor facing and next adjacent, formed by the control pin front annular surface with decreasing radius and the housing itself formed by the rear annular surface upon pressurization of the annular channel in the direction of the rotor acting resulting force results.

The hydraulic force resulting from the operating pressure prevailing in the hydraulic system initially tends to push rotor and control pin apart. However, this operating pressure is fed back depending on the direction of rotation on the respective annular channel and generates on the one annular surface of the control pin, the above-mentioned resulting force, whereby according to the invention Control pin and the rotor over the entire operating pressure range with a defined adjustable excess force are pressed together. The reversal of the suction and pumping of the hydraulic fluid when changing the direction of rotation takes place automatically by the inventive arrangement of Saugrückschlagventile in the control pin.

The inventive principle thus lies in the axial arrangement of the control pin on the end face of the rotor and the pressing of these two parts dependent on the operating pressure in the hydraulic system. As a result, the connection point of these parts is not only relatively tight in operation and thus low in leakage; even with wear (abrasion) of the end face of the rotor, the required adjustment takes place automatically and automatically. Overall, the invention provides a simpler in the production and assembly and thus more cost-effective pump, which is extremely low leakage even during operation despite wear.

Advantageously, the front face of the rotor adjacent the front annular channel and the end face of the rotor remote rear ring channel are connected via a respective transverse bore with the associated line connection of Saugrückschlagventile, resulting in a particularly simple production.

In order to prevent unwanted leakage from the annular channels of the control pin, this has a circular cylindrical shell and is the rear and front annular channel of two circumferential seals adjacent.

The resulting by the pressure prevailing in the hydraulic system operating pressure axial and radial forces are advantageously compensated by the fact that the rotor is rotatably mounted on its side facing away from the end face by means of at least one designed as a deep groove ball bearing axial and / or radial bearing.

Further expedient refinements and further developments are characterized in the remaining subclaims.

Figur 1

eine erste Ausführungsform Pumpe gemäss der Erfindung, im schematischen Querschnitt;

Figur 2

einen Schnitt II-II nach Figur 1;

Figur 3

einen Schnitt III-III nach Figur 1;

Figur 4

einen Schnitt IV-IV nach Figur 1;

Figur 5

eine Einzelheit in Fig. 1, im grösserem Massstab und

Figur 6

eine alternative Ausführungsform der Pumpe.

An embodiment of the invention will be explained below with reference to the drawing. In this shows:

FIG. 1

a first embodiment pump according to the invention, in schematic cross section;

FIG. 2

a section II-II of Figure 1;

FIG. 3

a section III-III of Figure 1;

FIG. 4

a section IV-IV of Figure 1;

FIG. 5

a detail in Fig. 1, on a larger scale and

FIG. 6

an alternative embodiment of the pump.

The pump unit formed by the actual hydraulic reversible pump 1, 2, 12 and the electric motor 9 flanged to it on one side thereof and driving the latter has, as shown in FIG. 1, a housing 12 on the other side of which a tank 11 for the Hydraulic fluid is attached, which is preferably formed of oil. The pump is provided with two ports 13,14, of which in one direction of rotation one serves as a pressure for the supply line and the other as a line connection for the return line and -in the opposite direction of rotation - vice versa, and with a connected to the tank 11 filling port 17 provided.

In the housing 12 with respect to the same rotationally fixed control pin 2 is provided with a circular cylindrical jacket. To a housing-fixed axis of rotation, a rotor 1 is rotatably mounted, which has three radially movable, with its outer ends on an eccentric 4 supporting the pump piston 3. This eccentric bearing 4 is executed in the embodiment shown as a rolling bearing. The arranged in the axial direction next to the control pin 2 rotor 1 is pressed against this in a pressureless state with the force of a spring 8. On its side facing away from the end face of the rotor 1 is rotatably supported by means of two deep groove ball bearings 10 about the housing-fixed axis of rotation.

As shown in FIG. 3, the inner ends of the pumping pistons 3 each terminate in a volume-changing piston space. Each piston chamber has an axially extending and in the control pin 2 facing end side of the rotor 1 opening bore 3a.

The control pin 2 is provided with a hardened control plate 2a with two control surfaces (FIG. 2A) formed as control rods 2b, 2c or alternatively with two bores 2b, 2c (FIG. 2B) which abut against the end face of the rotor 1 in such a way that they act during the control Rotation of the rotor 1 with the opening into the end face of the rotor 1 Holes 3a are temporarily aligned. In the control pin 2 are also two with their tank facing tank port 5c, 6c with a tank 11 and with its tank 11 remote line connection 5d, 6d with one of the control surfaces 2b, 2c and one of the two ports 13,14 connected Saugrückschlagventile 5.6 provided. For the connection 13, this results from Figure 4, which is connected via a tap hole 18 with the front annular channel 6a. Accordingly, the terminal 14 is connected via a tap hole, not shown, to the rear annular channel 5a. The control surfaces 2b, 2c are each connected to the tank 11 via one of the suction check valves 5, 6. In the pressureless state, the end face of the rotor 1 is pressed with the spring 8 designed as a spring element oil-tight to the control mirror 2 a of the control pin 2.

The line connection 5d of the one-rear suction check valve 5 is connected to a provided between the housing 12 and the jacket of the control pin 2 disposed therein, circumferential, rear annular channel 5a via an associated transverse bore 5b. Likewise, the line connection 6d of the -vorderen- Saugrückschlagventils 6 is connected to a provided between the housing 12 and the jacket of the control pin 2 disposed therein, circumferential, front annular channel 6a via an associated transverse bore 6b. As FIG. 5 shows, its front annular surface 15 delimiting the front annular channel 6a on its side nearest the end face of the rotor 1 is formed by a region of the control pin 2 with decreasing radius in the form of a shoulder, whereas that of the front annular channel 6a on its relative the end face of the rotor 1 remote side limiting rear annular surface 16 is formed by a portion of the housing 12. It is also adjacent to the rear (5a) and the front annular channel 6a on each side a circumferential seal 9a, 9b, 9c arranged.

Depending on the direction of rotation of the electric motor 9 is sucked during the first half turn oil from the tank 11, of the individual pump piston 3 through the bore 3a, for example via the one suction check valve 5 or the one rear annular channel 5a and during the next half turn in the other front Ring channel 6a promoted. The other suction check valve 6 is closed in this case, so that it is pumped out of the one serving as a pressure connection port 13 (Figure 4). If the direction of rotation changes, oil is sucked in via the other suction check valve 6 or the other front annular channel 6a and conveyed into the rear annular channel 5a. In this case, the former one suction check valve 5 is closed.

FIG. 6 shows another embodiment of the suction check valve 5, 6, whose two valve balls on each valve seat seal the through-channel, which extends between the two valve seats and open into the tank via a branch channel which is not described in more detail. The two valve balls are controlled by a valve stem 19 so that when closing the one Saugrückschlagventils 5, i. with resting on the valve seat valve ball, the valve ball of the other suction check valve 6 is lifted by the valve stem 19 from its seat and thus opened, so either only one or the other suction check valve open and the other is closed.

The resulting from the system pressure hydraulic Force that presses apart the rotor 1 and the control pin 2 on the control plate 2a by feedback of the system pressure depending on the direction of rotation on the one, the control mirror 2a and the end face of the rotor next adjacent annular surface of a rear (5a) or the other front annular channel 6a compensated. As a result, the control pin 2 and the rotor 1 are pressed against each other over the entire operating pressure range with a definable excess force, so that their connection point in operation low leakage and thus is relatively dense. When wear (abrasion) of the end face of the rotor is automatically the required adjustment.

The resulting by the system pressure axial and radial forces are absorbed by the two deep groove ball bearings 10 and intercepted via the retaining ring 7 in the housing 12.

Claims (16)

1. Hydraulic pump preferably driven by an electric motor (9) comprising two connections (13, 14), of which respectively one acts as the compression connection, and the other acts as the suction connection in the case of one rotational direction, and vice versa in the case of the opposite rotational direction;
   with a control pintle (2), which is rotationally rigid with reference to a housing (12);
   and with a rotor (1), which is rotatable about a rotational axis mounted rigidly on the housing, and provides several, preferably three pump pistons (3) displaceable in the radial direction, supported with their outer ends on an eccentric bearing (4), of which the internal ends close off a piston chamber of variable volume,
   wherein the control pintle (2) provides two control surfaces (2b, 2c) and, with the two control surfaces (2b, 2c), is in contact in the axial direction adjacent to the rotor (1) with one end surface of the latter,
   and wherein, in each case, one borehole (3a) connected to each piston chamber is provided, which extends axially - parallel to the axis of rotation - and opens at the end surface of the rotor (1),
   characterised in that

   - a tank (11) is disposed in the housing;

   - that a first suction check valve (5), which can be connected by its first tank connection (5c), facing towards the tank, to the tank (11), and can be connected by its first line connection (5d), facing away from the tank (11), both to one of the control surfaces (2b, 2c) and also to one of the two connections (13, 14),
   and a second suction check valve (6), which can be connected by its second tank connection (6c), facing towards the tank, to the tank (11), and can be connected by its second line connection (6d), facing away from the tank (11), both to the other control surface (2b, 2c) and also to the other one of the two connections (13, 14), are provided in the control pintle (2);

   - and that each line connection, namely the first and the second line connection (5d, 6d), of every suction check value, namely the first and the second suction check valve (5, 6), is connected respectively to a peripheral, front (6a) or respectively rear (5a) annular channel provided between the housing (12) and the casing of the control pintle (2) arranged therein, of which the front annular surface (15) limiting the annular channel at its side most nearly adjacent to the end surface of the rotor (1) is formed by a region of the control pintle (2) of decreasing radius, and of which the rear annular surface (16) limiting the annular channel at its side remote from the end surface of the rotor (1), is formed by a region of the housing (12).
2. Pump according to claim 1,
   characterised in that
   the front annular channel (6a), most nearly adjacent to the end surface of the rotor (1), and the rear annular channel (5a), more remote from the end surface of the rotor (1), are connected respectively via a transverse borehole (5b, 6b) to the associated line connection (5d, 6d) of the suction check valve (5, 6).
3. Pump according to claim 1 or 2,
   characterised in that
   the control pintle (2) provides a cylindrical casing, and the rear annular channel and the front annular channel (5a, 6a) are adjacent on each side to a peripheral seal (9a, 9b, 9c).
4. Pump according to any one of claims 1 to 3,
   characterised in that
   the control pintle provides two kidney-shaped control surfaces (2b, 2c).
5. Pump according to any one of claims 1 to 3,
   characterised in that
   the control pintle provides two control boreholes as control surfaces (2b, 2c).
6. Pump according to any one of claims 1 to 5,
   characterised in that
   the control pintle (2) provides a control plate (2a), and that the control surfaces (2b, 2c) of the control pintle (2) are disposed within the control plate (2a).
7. Pump according to claim 6,
   characterised in that
   the rotor (1) provides a control plate, which provides a different hardness by comparison with the control plate (2a) of the control pintle (2).
8. Pump according to any one of claims 1 to 7,
   characterised in that
   the rotor (1), which is arranged alongside the control pintle (2) in the axial direction, and the control pintle (2) are pressed against one another in the pressureless condition by the force of a spring (8).
9. Pump according to any one of claims 1 to 8,
   characterised in that
   the eccentric bearing (4) is designed as a sliding bearing or roller bearing.
10. Pump according to any one of claims 1 to 9,
    characterised in that
    the rotor (1) is mounted in a rotatable manner at its side facing away from the end surface by means of at least one axial bearing (10).
11. Pump according to any one of claims 1 to 9,
    characterised in that
    the rotor (1) is mounted in a rotatable manner at its side facing away from the end surface by means of at least one radial bearing (10).
12. Pump according to claim 10 or 11,
    characterised in that
    the axial bearing and/or the radial bearing is designed as a deep-groove ball-bearing (10).
13. Pump according to claim 1,
    characterised in that
    it is designed as a reversible pump.
14. Pump according to claim 1,
    characterised in that
    the tank (11) adjoins the control pintle (2) at its side facing away from the rotor (1).
15. Pump according to claim 1,
    characterised in that
    the two suction check valves (5, 6) disposed in the control pintle (2) each provide one valve ball sealing off the respective through channel extending between the two valve seatings and opening into the tank;
    and that the two valve balls are controlled in such a manner by a valve plunger (19), that when the one suction check valve (5) is closed with the valve ball disposed on the valve seating, the valve ball of the other suction check valve (6) is lifted from its seating by the valve plunger (19) and is therefore opened.
16. Pump according to claim 15,
    characterised in that
    the through channel extending between the two valve seatings opens into the tank (11) via a branch channel.

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