EP2435704B1 - Pump, particular vane-type pump - Google Patents

Description

The invention relates to a pump, in particular a vane pump, with at least one displacement body, which is arranged between two pressure plates, which are acted upon on their side facing away from the displacer with a delivery pressure of the pump to minimize leakage gaps between the displacer and the pressure plates.

From the European patent EP 0 906 512 B1 is a vane pump with a wing-receiving rotor and with two close to the rotor pressure plates known, at least one of the two pressure plates is provided with inlet and outlet ports, which establish a fluid connection between a pressure range and an under wing area. One of the pressure plates has an opening which provides fluid communication between a pressure area and a pressure space bounded by this pressure plate.

EP19846815 represents the closest prior art. The object of the invention is a pump, in particular a vane pump, with at least one displacer, which is arranged between two pressure plates, which are acted upon on their the displacer backs facing away with a delivery pressure of the pump to leakage gaps between the displacer and the pressure plates to minimize, which has a high efficiency and / or a long life.

The object is with a pump, in particular a vane pump, with at least one displacement body, which is arranged between two pressure plates, which are acted upon on their the displacer rear sides substantially with a delivery pressure of the pump to minimize leakage gaps between the displacer and the pressure plates , in that the rear side of one of the pressure plates can be connected to a pressure relief space via a valve device combined with a flow control valve in order to lower the pressure acting on the back side of this pressure plate in a targeted manner. The pump is preferably a vane pump with at least one wing as a displacement body. However, the invention also relates to positive displacement pumps of a different type, such as roller-cell pumps. The pump is preferably designed as a hydraulic pump and serves to pressurize a working medium, in particular a hydraulic medium such as oil, and to promote at least one consumer. The loading of the back sides of the two pressure plates with the delivery pressure of the pump can lead to undesirable wear on the displacement plate coming into contact with the pressure plates at high rotational speeds. This wear, especially an undesirable eating, is particularly high at high speeds and a high discharge pressure of the pump. According to one essential aspect of the invention, the pressure on the back of preferably only one of the pressure plates is selectively reduced by means of the valve device to the wear, in particular the risk of contact between the displacement body, in particular a rotor and / or a wing, and the pressure plates to minimize. The function of the pressure plates at a low speed and / or at a low delivery pressure of the pump is not affected by the invention, since the delivery pressure of the pump by means of the valve means can be switched to the backs of a pressure plate to the leakage gaps between the displacer and to minimize the pressure plates at low speed. The flow control valve is preferably an already existing flow control valve which serves to keep the speed-dependent volumetric flow provided by the pump independent of the pressure applied to the consumer and the temperature of the pressure medium for the consumer as constant as possible.

A preferred embodiment of the pump is characterized in that the connection between the back of one of the pressure plates and the pressure relief space depending on the flow rate, the delivery pressure and / or the speed of the pump is fully or partially released by the valve means to the on the To lower the pressure acting on the rear side of this pressure plate in a targeted manner. The pressure relief space can be, for example, a tank for the working medium, which is exposed to ambient pressure. Due to the targeted pressure reduction on the back of one of the printing plates, a sufficient distance between the displacer and the printing plates can be ensured, in particular at a high delivery pressure and optionally simultaneously high flow rate of the pump.

A further preferred embodiment of the pump is characterized in that the valve device comprises a pressure relief passage, which the Rear side of one of the pressure plates in dependence on the position of a closing body with the pressure relief space connects. By the closing body, the connection of the back of one of the pressure plates with the pressure relief space can be fully or partially released or interrupted.

A further preferred embodiment of the pump is characterized in that the closing body belongs to a valve piston of the valve device. The closing body is preferably connected in one piece with the valve piston of the valve device. As a result, the manufacture and assembly of the valve device or the pump can be considerably simplified.

A further preferred embodiment of the pump is characterized in that the valve device combined with the flow control valve interrupts a connection between a pressure port and the pressure relief passage when the pump delivers large volume flows. The flow control valve serves to keep the speed-dependent volume flow provided by the pump independent of the pressure applied to the consumer and the temperature of the pressure medium for the consumer as constant as possible. For this purpose, the flow control valve is provided with a pressure compensator. The valve piston of the combined with the flow control valve device has the function of a pressure compensator. With this pressure compensator, the rise of a pressure difference at a throttle of the flow control valve is detected, which is a measure of the volume flow to the consumer. The occurring adjustment of the functioning as a pressure balance valve piston is used for targeted lowering of the pressure on the back of one of the printing plates.

A further preferred embodiment of the pump is characterized in that the closing body releases a connection between a suction pressure port of the flow control valve and the pressure relief channel when the pump promotes large volume flows Thus, acting on the back of one of the pressure plates discharge pressure in a controlled by the flow control valve working area of Pump switched off.

A further preferred embodiment of the pump is characterized in that the closing body the connection between a pressure area on Flow control valve and the pressure relief channel releases when the pump promotes small volume flows. As a result, the delivery pressure of the pump acts in a non-regulated by the flow control valve workspace of the pump on the back of a pressure plate.

A further preferred embodiment of the pump is characterized in that the closing body comprises a guide sleeve with an outer annular groove. The guide sleeve serves to move the valve piston with the closing body to and fro. The annular groove allows communication between the suction pressure port of the flow control valve and the pressure relief passage to selectively lower the pressure acting on the back of one of the pressure plates.

A further preferred embodiment of the pump is characterized in that the closing body comprises an annular body from which the guide sleeve extends and on which a control edge is formed, which represents the control edge of the pressure compensator. The annular body preferably has on the side facing away from the guide sleeve a stepped pin with a through hole, which serves to create an annular gap together with an opening in a terminal screw of the valve device, which comprises a throttle device, in particular a measuring throttle, for generating the control differential pressure represents the flow control valve. The control edge on the ring body, which opens or interrupts, controls the connection to the suction pressure connection of the flow control valve, thus regulating the unnecessary volume flow, which is not required by the consumer, back into the suction area of the pump.

A further preferred embodiment of the pump is characterized in that the valve means comprises a pressure relief valve which releases the connection between the back of one of the pressure plates and the pressure relief space when the pressure at the pressure port exceeds a predetermined value. Alternatively or in addition to the flow control valve, an existing pressure limiting valve can be used to selectively lower, that is to say, switch off the delivery pressure acting on the back side of one of the pressure plates.

• Figur 1 eine vereinfachte Darstellung einer erfindungsgemäßen Pumpe mit zwei Druckplatten, die beide mit dem Förderdruck der Pumpe beaufschlagt sind;
• Figur 2 die Pumpe aus Figur 1, wobei der Druck auf die Rückseite einer der beiden Druckplatten gezielt abgesenkt ist;
• Figur 3 ein kartesisches Koordinatendiagramm mit einer schematischen Kennlinie eines Stromregelventils der Pumpe und
• Figur 4 eine ähnliche Darstellung wie in Figur 1 gemäß einem weiteren Ausführungsbeispiel mit einem Druckbegrenzungsventil.

Further advantages, features and details of the connection will become apparent from the following description in which, with reference to the drawings, various embodiments are described in detail. Show it:

• FIG. 1 a simplified representation of a pump according to the invention with two pressure plates, which are both acted upon by the delivery pressure of the pump;
• FIG. 2 the pump off FIG. 1 , wherein the pressure on the back of one of the two pressure plates is deliberately lowered;
• FIG. 3 a Cartesian coordinate diagram with a schematic characteristic of a flow control valve of the pump and
• FIG. 4 a similar representation as in FIG. 1 according to a further embodiment with a pressure relief valve.

In the FIGS. 1 . 2 and 4 In each case, a pump 1 is shown with a housing part 2 shown in simplified form. In the pump 1 is a vane pump, as for example in FIG. 1 and the associated description of the European patent specification EP 0 906 512 B1 is disclosed. The housing part 2 of the vane pump 1 comprises a contoured ring 4, which is also referred to as a lifting ring. Within the contour ring 4, a rotor 5 is rotatably driven, as indicated by an arrow 6.

The rotor 5 is used in a known manner to at least one (not shown) wing within the contour ring 4 to move slidably. The rotor 5 and / or the wing represent or represents one or more displacement body, which is or are so movable within the contour ring 4 and between two pressure plates 11, 12 that two substantially crescent-shaped delivery spaces within a stroke contour of the contour ring 4 of preferably be passed through several wings.

The normally flat pressure plates 11, 12 are partially exaggerated strongly curved or shown bent to make the function of the pressure plates 11, 12 visible under pressure. On a the rotor 5 facing away Rear side 13 of the pressure plate 12 acts, as indicated by arrows 14, 15, a delivery pressure of the pump 1. The application of the delivery pressure 14, 15 causes the pressure plate 12 deformed towards the rotor 5.

The pressure plate 11 rests with its rear side 18 facing away from the rotor 5 against an annular supporting and / or sealing device 20, radially inside of which a pressurizing space 24 is formed. In FIG. 1 is indicated by an arrow 25 that the pressurization chamber 24 and the back 18 of the pressure plate 11 as well as the back 13 of the pressure plate 12 is acted upon by the delivery pressure of the pump 1.

By the arrow 25 is in FIG. 1 a connection between the pressurization chamber 24 on the back 18 of the pressure plate 11 and a pressure relief channel 26 indicated, which is connected in the illustrated embodiment to a flow control valve 30, which serves to keep the funded by the pump 1 volume flow constant. The flow control valve 30 includes a pressure port 31, which may be configured as a pressure port of the pump 1. In or at the pressure port 31, there is substantially the delivery pressure of the pump 1.

The flow control valve 30 further includes a suction port 32 communicating with the suction side of the pump 1. The pressure port 31 and the suction port 32 are provided in a valve housing 34 which may be integrated into the housing 2 of the pump 1. In the valve housing 34, a valve space 35 is recessed, which has the shape of a blind hole, in which a terminal screw 36 is screwed, which includes the pressure port 31.

In the valve chamber 35, a valve piston 38 is guided reciprocally movable. The valve piston 38 is biased by a biasing spring 81 within the valve chamber 35 against the terminal screw 36 and comprises an annular body 40, on which a control edge 41 is formed.

From the annular body 40 is a guide sleeve 42, which includes an interior space with a pressure region 43 which is open to the valve chamber 35 out. On the guide sleeve 42 opposite side goes from the ring body 40 a stepped pin 45, which comprises a central through hole 46 which connects the pressure port 31 with the inner space or pressure region 43 of the guide sleeve 42. The pin 45 extends from a pressure control chamber 48 through an opening 80 of the terminal screw 36 to the pressure port 31 and forms with the opening 80, the measuring throttle of the flow control valve in the form of an annular gap.

The pressure control chamber 48 is, as well as the pressure port 31, the inner space 43 of the guide sleeve 42 and the valve chamber 45 is applied to the pressure difference at the measuring throttle substantially with the delivery pressure of the pump 1, by an arrow 49 is indicated that the back 13 of the Pressure plate 12 is acted upon via the pressure control chamber 48 of the flow control valve 30 with the delivery pressure of the pump 1.

In FIG. 2 is indicated by an arrow 50 that the pressurization chamber 24 via the pressure relief passage 26 and an annular groove 52 with the suction port 32 of the flow control valve 30 is connectable to relieve the back 18 of the pressure plate 11. To illustrate the relief of the pressure plate 11, the pressure plate 11 in FIG. 2 flat and not curved, as in FIG. 1 represented. The annular groove 52 is formed on the outside of the guide sleeve 42.

In FIG. 3 is shown in a Cartesian coordinate diagram with an x-axis 54 and a y-axis 55, a schematic curve 56 of the flow control valve 30 and the pump 1. On the y-axis 55, the volume flow is shown, which is funded by the pump 1 through the flow control valve 30. On the x-axis 54, the speed during operation of the pump 1 is shown. The characteristic curve 56 comprises an unregulated region 58, in which the flow control valve 30 has not yet opened the outflow to the suction region 32 and the characteristic 56 increases linearly, and a regulated region 59, in which the flow control valve increasingly opens, and therefore the characteristic curve 56 substantially parallel to the x-axis 54 runs.

The loading of the pressure plates 11, 12 on their rear sides 13, 18 with the delivery pressure of the pump 1 serves to the pressure acting on the other side of the pressure plates 11, 12 in the displacing delivery cells between the rotor 5, wing and contour ring 4 and is therefore also referred to as pressure plate compensation. The pressure plate compensation is changed according to an essential aspect of the invention in dependence on the rotational speed of the pump 1.

In the FIGS. 2 and 3 it can be seen that the compensation, that is, deflection, of the pressure plate 12 remains, and only the compensation of the pressure plate 11 is degraded. For this purpose, the pressurization space 24 is on the back 18 of the pressure plate 11 in the FIGS. 1 and 2 with the valve chamber 35 of the flow control valve 30 in conjunction.

The position of this connection is selected so that in the unregulated region 58 of the pump 1, the valve piston 38, in particular the guide sleeve 42, the pressure relief passage 26 completely releases, as can be seen in FIG. 1 sees. As a result, both pressure plates 11, 12 are essentially acted upon by the delivery pressure of the pump 1, that is fully compensated. This provides the advantage that an undesirable leakage between the pressure plates 11, 12 and the rotor 5 can be kept as low as possible.

In the controlled area 59 of the pump 1, the valve piston 38 moves with the guide sleeve 42, as can be seen in FIG. 2 sees, so away from the terminal screw 36 that the guide sleeve 42 initially covers the mouth of the pressure relief passage 26 in the valve chamber 35 and then releases to the suction port. Via the annular groove 52 on the outside of the guide sleeve 42, the pressure in the pressure relief passage 26 can be reduced to the suction port 32 of the flow control valve 30 out.

At the in FIG. 4 illustrated embodiment, in contrast to the preceding embodiment, in the FIGS. 1 and 2 26 denoted pressure relief channel not available. An arrow 65 indicates that the pressurization chamber 24 on the rear side 18 of the pressure plate 11 is acted upon by the valve chamber 35 of the flow control valve 30 essentially with the delivery pressure of the pump 1. A pressure relief passage 66 extends outside the valve chamber 35 through the valve housing 34.

An arrow 67 indicates that the pressure in the pressurization space 24 is degradable via the pressure relief passage 66 which, as indicated by a further arrow 68, communicates with a pressure relief space, such as a tank. The pressure relief passage 66 is closed by a valve piston 70 which is biased by a spring 71 against a through hole 74 which connects the pressure relief passage 66 with the valve chamber 35 of the flow control valve 30.

The valve piston 70 and the spring 71 represent a pressure relief valve 75, via which the pressure in the valve chamber 35 of the flow control valve 30 can be reduced when a predetermined pressure limit is exceeded. When the pressure relief valve 75 opens, then the pressure application chamber 24 is simultaneously relieved via the pressure relief passage 66, as indicated by the arrows 67 and 68. Thus, as well as in the in the FIGS. 1 and 2 illustrated embodiment, a one-sided printing plate compensation can be achieved in a simple manner.

LIST OF REFERENCE NUMBERS

1 pump 45 spigot 2 casing 46 Through Hole 4 contour ring 48 Pressure control chamber 5 rotor 49 arrow 6 arrow 50 arrow 11 printing plate 52 ring groove 12 printing plate 54 X axis 13 back 55 y-axis 14 arrow 56 curve 15 arrow 58 unregulated area 18 back 59 regulated area 20 Supporting and / or sealing device 65 arrow 24 pressurization 66 Pressure relief duct 25 arrow 67 arrow 26 Pressure relief duct 68 arrow 30 Flow control valve 70 plunger 31 pressure connection 71 feather 32 suction 74 Through Hole 34 valve housing 75 Pressure relief valve 35 valve chamber 80 opening 36 terminal screw 81 feather 38 plunger 40 ring body 41 control edge 42 guide sleeve 43 Interior, pressure range

Claims (10)

1. Pump, in particular vane-type pump, having at least one displacement body (5) which is arranged between two pressure plates (11, 12) that are subjected substantially to a delivery pressure of the pump (1) on their rear sides (18, 13) facing away from the displacement body (5), in order to minimize leakage gaps between the displacement body (5) and the pressure plates (11, 12), characterized in that the rear side (18) of one of the pressure plates (11) is connectable to a pressure relief space via a valve device (30; 75) combined with a flow control valve (30), in order to selectively lower the pressure acting on the rear side (18) of said pressure plate (11).
2. Pump according to Claim 1, characterized in that the connection of the rear side (18) of one of the pressure plates (11) to the pressure relief space is entirely or partially opened up by the valve device (30; 75) depending on the delivery rate, the delivery pressure or/and on the rotational speed of the pump (1), in order to selectively lower the pressure acting on the rear side (18) of said pressure plate (11).
3. Pump according to either of the preceding claims, characterized in that the valve device (30; 75) comprises a pressure relief duct (26; 66) which connects the rear side (19) of one of the pressure plates (11) to the pressure relief space depending on the position of a closing body.
4. Pump according to Claim 3, characterized in that the closing body belongs to a valve piston (38; 70) of the valve device.
5. Pump according to Claim 3 or 4, characterized in that the valve device (30) combined with the flow control valve interrupts a connection between a pressure port (31) and the pressure relief valve (26) when the pump is delivering large volume flows.
6. Pump according to Claim 5, characterized in that the closing body opens up a connection between a suction-pressure port (32) of the flow control valve (30) and the pressure relief duct (26) when the pump (1) is delivering large volume flows.
7. Pump according to Claim 6, characterized in that the closing body opens up the connection between a pressure region (43) on the flow control valve (30) and the pressure relief duct (26) when the pump (1) is delivering small volume flows.
8. Pump according to one of Claims 5 to 7, characterized in that the closing body comprises a guide sleeve (42) having an outer annular groove (52).
9. Pump according to one of Claims 5 to 8, characterized in that the closing body comprises an annular body (40) from which the guide sleeve (42) extends and on which a control edge (41) is formed.
10. Pump according to one of Claims 3 to 9, characterized in that the valve device (75) comprises a pressure limiting valve which opens up the connection between the rear side (18) of one of the pressure plates (11) and the pressure relief space when the pressure at the pressure port (31) exceeds a predetermined value.

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