EP2049800B1 - Feed pump - Google Patents

Abstract

The invention relates to a feed pump for hydraulic media, having an inlet (12) and an outlet (16), wherein a feed pressure is applied at the outlet, comprising a pressure reducing element (20) connected to the outlet, the pressure reducing element having a system pressure applied at the outlet (24) thereof and being connected to a consumer (26), wherein the outlet is connected to a first inlet (28) of a pump regulator (30), the second inlet (32) thereof being connected to the outlet of the pressure reducing element, and the pump regulator positioning the feed pump (10) in the direction of maximum feed if the system pressure (ρ2) is lower than a minimum pressure (46), or if the system pressure is lower than the feed pressure, and wherein a pressure limiter (34) is connected in parallel to the pump regulator such that at the first inlet (36) thereof the feed pressure is applied, and that at the control inlet (40) the system pressure is applied, wherein the pressure limiter opens if the feed pressure is greater than a target value (42).

Description

The invention relates to a feed pump for hydraulic media.

Feed pumps have a delivery volume, which depends on the speed of the feed pump and its drive. Depending on the system resistance of the consumer or the facilities consuming the pumped hydraulic medium, the system pressure also depends on the delivery volume. In general, there is a desire to keep the system pressure at a constant level or at least within a predetermined range.

From the DE 101 04 635 A1 For example, a method of maintaining a constant output of a feed pump has become known. In this method, depending on the output pressure of the feed pump whose drive speed is controlled. For this purpose, it requires a controllable transmission, which in some circumstances, that is, depending on the performance of the feed pump, consuming and expensive.

The invention is therefore based on the object, a delivery pump, in particular a pump control to propose, which is easier to set to a desired system pressure.

This object is achieved with a feed pump having the features of claim 1.

Advantageous embodiments, advantages, features and details of the invention will become apparent from the subclaims and the following description in which preferred embodiments are described in detail with reference to the drawing. The features shown in the drawing and in the description as well as in the claims mentioned may each be essential to the invention individually or in any desired combination.

Figur 1

ein Blockschaltbild einer ersten Ausführungsform der Erfindung;

Figur 1a

eine vergrößerte Wiedergabe des Druckbegrenzers gemäß Figur 1;

Figur 2

ein Anwendungsbeispiel der in der Figur 1 dargestellten Schaltung bei einer Flügelzellenpumpe mit verstellbarem Rotor;

Figur 3

eine Variante der Ausführungsform gemäß Figur 1 mit verlustfreier Förderung;

Figur 3a

eine vergrößerte Wiedergabe des Druckbegrenzers gemäß Figur 3;

Figur 4

eine Variante der Ausführungsform gemäß Figur 1 mit einem innerhalb einer Bandbreite geregelten Systemdruck;

Figur 4a

eine vergrößerte Wiedergabe des Druckbegrenzers gemäß Figur 4;

Figur 5

ein Anwendungsbeispiel der in der Figur 4 dargestellten Schaltung bei einer Flügelzellenpumpe mit verstellbarem Rotor;

Figur 6

eine Variante der Ausführungsform gemäß Figur 4 mit einem innerhalb einer Bandbreite geregelten Systemdruck mit verlustfreier Förderung;

Figur 6a

eine vergrößerte Wiedergabe des Druckbegrenzers gemäß Figur 6;

Figur 7

die Variante gemäß Figur 4 bei Ausfall der Kennfeldregelung;

Figur 8

ein Blockschaltbild einer weiteren Ausführungsform der Erfindung mit Konstantdruckregelung;

Figur 9

ein Anwendungsbeispiel der in der Figur 8 dargestellten Schaltung bei einer Flügelzellenpumpe mit verstellbarem Rotor;

Figur 10

ein Blockschaltbild einer weiteren Ausführungsform der Erfindung mit Konstantdruckregelung;

Figur 11

ein Anwendungsbeispiel der in der Figur 10 dargestellten Schaltung bei einer Flügelzellenpumpe mit verstellbarem Rotor;

Figur 12

ein Anwendungsbeispiel einer weiteren Ausführungsform der Erfindung mit Kennfeldregelung in einer Flügelzellenpumpe mit verstellbarem Rotor;

Figur 13

ein Anwendungsbeispiel einer weiteren Ausführungsform der Erfindung mit Kennfeldregelung in einer Flügelzellenpumpe mit verstellbarem Rotor;

Figur 14

eine Variante des Anwendungsbeispiel der Figur 12 bei Ausfall der Kennfeldregelung;

Figur 15

eine Variante des Anwendungsbeispiel der Figur 13 bei Ausfall der Kennfeldregelung; und

Figur 16

eine Variante der Erfindung gemäß Figur 8.

In the drawing show:

FIG. 1

a block diagram of a first embodiment of the invention;

FIG. 1a

an enlarged view of the pressure limiter according to FIG. 1 ;

FIG. 2

an example of application in the FIG. 1 shown circuit in a vane pump with adjustable rotor;

FIG. 3

a variant of the embodiment according to FIG. 1 with lossless promotion;

FIG. 3a

an enlarged view of the pressure limiter according to FIG. 3 ;

FIG. 4

a variant of the embodiment according to FIG. 1 with system pressure controlled within a bandwidth;

FIG. 4a

an enlarged view of the pressure limiter according to FIG. 4 ;

FIG. 5

an example of application in the FIG. 4 shown circuit in a vane pump with adjustable rotor;

FIG. 6

a variant of the embodiment according to FIG. 4 with system pressure controlled within a bandwidth with lossless delivery;

FIG. 6a

an enlarged view of the pressure limiter according to FIG. 6 ;

FIG. 7

the variant according to FIG. 4 in case of failure of the map control;

FIG. 8

a block diagram of another embodiment of the invention with constant pressure control;

FIG. 9

an example of application in the FIG. 8 shown circuit in a vane pump with adjustable rotor;

FIG. 10

a block diagram of another embodiment of the invention with constant pressure control;

FIG. 11

an example of application in the FIG. 10 shown circuit in a vane pump with adjustable rotor;

FIG. 12

an application example of another embodiment of the invention with map control in a vane pump with adjustable rotor;

FIG. 13

an application example of another embodiment of the invention with map control in a vane pump with adjustable rotor;

FIG. 14

a variant of the application example of FIG. 12 in case of failure of the map control;

FIG. 15

a variant of the application example of FIG. 13 in case of failure of the map control; and

FIG. 16

a variant of the invention according to FIG. 8 ,

That in the FIG. 1 shown block diagram shows a total of 10 designated feed pump whose volume is adjustable. The feed pump 10 has an input 12 which is connected to a tank 14. At the output 16, the delivery pressure P _{1 is present} and at the output 16, a pressure relief valve 18 is connected. This pressure relief valve 18 is also connected to the tank 14. If the delivery pressure P ₁ exceeds the opening pressure of the overpressure valve 18, eg 12 bar, then hydraulic medium flows into the tank 14. In addition, the outlet 16 is connected to a pressure-reducing element 20, for example a filter 22, a diaphragm or the like. At the output 24 of the pressure reducing element 20, the system pressure P _{2 is applied} . The subsidized by the pump 10 hydraulic medium reaches a consumer 26, for example, to an internal combustion engine of a motor vehicle. The hydraulic medium flows to the consumer 26 into the tank 14. Due to the pressure reducing element 20, the system pressure P _{2 is} smaller than the delivery pressure P ₁ .

The output 16 of the feed pump 10 is also connected to a first input 28 of a pump controller 30, the second input 32 is connected to the output 24 of the pressure reducing element 20. The reference numeral 46, the minimum pressure of the pump controller 30 is designated. The pump controller 30 adjusts the feed pump 10 in the direction of minimum delivery when the pressure at the second input 32 is greater than the pressure at the first input 28. The voltage applied to the second input 32 pressure P ₂ must exceed at least a minimum pressure, for example, 2 bar. Exceeds the voltage applied to the first input 28 or the minimum pressure of, for example, 2 bar the system pressure P ₂ , the pump controller 30 adjusts the feed pump 10 in the direction of maximum delivery. As long as the system pressure P _{2 is} below the minimum pressure, the feed pump 10 is moved in the direction of maximum delivery.

Parallel to the pump controller 30, a pressure limiter 34 is connected, the first input 36 is connected to the first input 28 of the pump controller 30 and the second input 38 is connected to the tank 14. At the control input 40, the system pressure P _{2 is applied} . The desired size 42 of the pressure limiter 34 is in particular adjustable and is 5.5 bar, for example. This means that the pressure limiter 34 connects the first input 36 to the second input 38 when the control input 40, a pressure exceeding the target size 42 is applied, ie when the system pressure P ₂ exceeds the target size. Hydraulic medium flows into the tank 14. As a result, the pressure at the first input 28 of the pump regulator 30 is reduced below the system pressure P ₂ , so that the pump regulator 30 adjusts the feed pump 10 in the direction of minimum delivery. As a result, the system pressure P _{2 also} drops until it drops below the value of the delivery pressure P ₁ , whereupon the pump regulator 30 is again adjusted in the direction of maximum delivery. The system pressure P ₂ is thus maintained between the minimum pressure and the desired size 42. From the pressure limiter 34 so hydraulic fluid is discharged into the tank 14, which has not yet passed the pressure reducing element 20. The system pressure P ₂ is changed only by an adjustment of the feed pump 10. In addition, it can be seen that between the output 16 of the feed pump 10 and the first input 28 of the pump controller 30, a throttle 48 is provided, which is in particular adjustable.

In the FIG. 1a the control piston 44 of the pressure limiter 34 is shown, wherein the control piston 44 is shown in its the first input 36 from the second input 38 separating position.

In the FIG. 2 an embodiment of a feed pump 10 is shown, to which the above-mentioned components are connected. The same components are provided with the same reference numerals. It can be seen that the feed pump 10 is a vane pump 50, whose rotor 52 is driven by a shaft 54 and in radial slots 56 carries a plurality of vanes 58, which rotate about sliding shoes 60 on an inner peripheral surface 62 of a stator 64. The stator 64 is pivotally mounted and has a pivot axis 66 and two pistons 68 and 70, the piston 68 and 70 of the pump controller 30 in the FIG. 1 correspond. By pivoting the stator 64 about the pivot axis 66 in the direction of the arrows 71, the delivery rate of the feed pump 10 is changed.

When in the FIG. 3 the second input 38 of the pressure limiter 34 is connected to the control input 40, so that when the pressure limiter 34 is open, the pressure applied to the first input 36 is transferred to the second input 38. Such a circuit has the significant advantage that it works lossless. From the FIG. 3a It can be seen that the second input 38 is connected directly to the control input 40 and that a displacement of the piston 44 causes a connection of the two inputs 36 and 38.

In the FIG. 4 the output 24 of the pressure reducing element 20 is connected to an electromagnetically driven control valve 72 (a 3/2-way valve). In the in the FIG. 4 illustrated working position of the control valve 72, the output 24 of the pressure reducing element 20 via the control valve 72 to a second control input 74 of the pressure limiter 34 is connected. As actuating forces for the pressure limiter 34 thus act on the first control input 40 applied system pressure P ₂ with the force acting within the control piston 44 force F ₁ and the voltage applied to the second control input 74 system pressure P ₂ with the force acting within the control piston 44 force F _2nd

The control piston 44 is in the FIG. 4a shown, from which it is clearly visible that the force F ₂ is greater than the force F ₁ due to the larger effective piston area, which acts only on an annular surface.

The control valve 72 is driven, for example, by a motor computer 76, whereby a map control of the feed pump 10 is made possible. The system pressure P ₂ can be set to any value between the minimum pressure (pump controller 30) and the desired size 42 (pressure limiter 34).

The FIG. 4 also shows a shut-off valve 78, which is controlled by the system pressure P ₂ and whose input 80 is connected to the output 82 of the control valve 72. The output 84 of the shut-off valve 78 is connected to the second input 32 of the pump controller 30 and to the control input 40 of the pressure limiter 34. Accordingly, the system pressure P _{2 is present} at the control input 40.

If the control valve 72 is controlled via the engine computer 76 and takes this in the FIG. 4 shown position, then the second control input 74 of the pressure limiter 34, the system pressure P ₂ and the pressure limiter 34 opens because the force F ₂ due to the system pressure P ₂ at the second control input 74 in addition to the force F _{1 of} the system pressure P ₂ at the control input 40th added, so that the two inputs 36 and 38 are connected to each other. The pump controller 30 adjusts the feed pump 10 in the direction of minimum delivery.

If the desired system pressure P _{2 is} reached, which is detected by the engine computer 76, the control valve 72 is switched over and closes the second control input 74. The system pressure P ₂ then rises until it reaches the desired value 42 or until the engine computer 76 in turn controls the control valve 72 controls and opens. In this way, the system pressure P ₂ according to a map control within a predetermined bandwidth can be set to desired different values.

The FIG. 5 shows the feed pump 10 with in the FIG. 4 illustrated circuit. In addition to that in the FIG. 2 In the illustrated embodiment, the pressure limiter 34 has the second control input 74, which is connected both to the control valve 72 and to the shut-off valve 78. The control valve 72 is actuated by the engine computer 76 and connects the second control input 74 via the shut-off valve 78 to the outlet 24 of the pressure-reducing element 20.

When in the FIG. 6 shown variant is as in the FIG. 3 , the control input 40 of the pressure limiter 34 connected to the second input 38. This is also clear from the FIG. 6a recognizable, which shows the control piston 44 in the pressure limiter 34. This variant represents a lossless control of the feed pump 10.

The FIG. 7 shows the position of the circuit in case of failure of the engine computer 76 and the map control. In this case, the control valve 72 is not activated and closes the output 24 in the direction of the shut-off valve 78 and the pressure limiter 34. Accordingly, there is no pressure at the second control input 74, so that the force F _{2 is} zero. At the second input 32 of the pump controller 30 is also no pressure, so that it assumes the position for maximum promotion. As a result, the system pressure P ₂ increases until the shut-off valve 78 is changed over and connects the output 24 with both the pump regulator 30 and with the pressure limiter 34. At the control input 40 is now the system pressure P ₂ and the pressure limiter 34 opens as soon as the pressure of the target size 42 is exceeded. Since then the pressure at the first input 36 drops, the pump controller 30 is adjusted towards minimum promotion. This means that in the event of failure of the engine computer 76, the system pressure P _{2 is determined} by the desired value 42. Also in this variant of the second input 38, as in the variant of Figures 3 and 6 , are connected to the control input 40. This variant would then also lossless.

The FIG. 8 shows a further variant of the invention, wherein hereinafter only on the differences compared to the variant of FIG. 1 will be received. The pressure limiter 34 is formed by a hydraulically driven control valve 86 (a 4/2-way valve), whose one, in particular adjustable control value 42 is for example 5.5 bar. The other control variable is supplied by the system pressure P ₂ , which is applied to the input 88. In the in FIG. 8 shown position of the control valve 86, the second input 32 of the pump controller 30 to the tank 14 and the first input 28 of the pump controller 30 to the output 16 of the feed pump 10 is connected. The pump controller 30 is thereby adjusted in the direction of maximum delivery. If the system pressure P ₂ exceeds the manipulated variable 42, then the control valve 86 changes position and applies the system pressure P ₂ to the second input 32 of the pump regulator 30 and connects the first input 28 of the pump regulator 30 to the tank 14. The pump regulator 30 is moved in the direction Adjusted minimum delivery, so that the system pressure P ₂ decreases. If the system pressure P ₂ falls below the manipulated variable 42, the control valve 86 returns to its starting position. The FIG. 9 shows this variant in an embodiment to which the above-mentioned components are connected. The same components are provided with the same reference numerals.

When in the FIG. 10 In the basic position of the control valve 86, the second input 32 of the pump regulator 30 with the tank 14 and the outlet 16 of the delivery pump 10 are connected directly to the consumer 26. The pump controller 30 is moved in the direction of maximum delivery, as long as the delivery pressure P _{1 is} below the manipulated variable 42. If the delivery pressure P ₁ exceeds the manipulated variable 42, then the output 24 of the pressure reducing element 20 with the tank 14 and the output 16 of the feed pump 10 with the second input 32 of the Pump controller 30 is connected, so that the pump controller 30 is adjusted in the direction of minimum promotion, since at the first input 28, a pressure is applied, which is smaller than the delivery pressure P ₁ due to the throttle 48. The FIG. 11 shows this variant in one embodiment.

When in the FIG. 12 shown variant of the invention, which is essentially the FIG. 5 corresponds, the pressure limiter 34 is formed as a 4/2-way valve 90. In this case, the first control input 40 with the shut-off valve 78 and the second control input 74 are connected both to the control valve 72 and to the shut-off valve 78. As soon as the delivery pressure P ₁ and the system pressure P ₂ exceed the manipulated variable 42, the directional control valve 90 reverses and connects the first input 28 to the tank 14, so that the pump regulator 30 is adjusted in the direction of minimum delivery.

In the embodiment according to the FIG. 13 connects the 4/2-way valve 90 to the second input 32 of the pump controller 30 to the tank, so that the pump controller 30 is initially adjusted in the direction of maximum promotion. In addition, the output 24 is connected to the system pressure P ₂ to the first input 28 of the pump controller 30. As soon as the delivery pressure P ₁ and the system pressure P ₂ exceed the manipulated variable 42, the directional valve 90 reverses and connects the second input 32 of the pump regulator 30 to the output 24 and the first input 28 of the pump regulator 30 to the tank 14, so that the pump regulator 30 is adjusted in the direction of minimum funding.

When in the FIG. 14 illustrated switching position, which of the FIG. 12 corresponds, the control valve 72 and the shut-off valve 78 are changed over. Since the second input 32 pump controller 30 is connected to the tank 14, the pump controller 30 is adjusted in the direction of maximum delivery. At the consumer 26, the system pressure P _{2 is applied} .

When in the FIG. 15 illustrated switching position, which of the FIG. 13 corresponds, the control valve 72 and the shut-off valve 78 are also changed over. The second input 32 of the pump controller 30 is connected to the tank 14 and the first input 28 to the output 24. The pump regulator 30 is adjusted in the direction of maximum delivery and the consumer 26 is the system pressure P ₂ on. An advantage of the latter variants is that the adjustment of the pump controller 30 are supplied pure oil side with the system pressure P ₂ . As a result, pollution-related failure can be largely excluded.

The FIG. 16 shows a variant of the invention according to FIG. 8 , wherein the pressure limiter 34 is formed as a 4/2-way valve 86 and not only via the input 88, to which the system pressure P ₂ is applied, but is also driven in parallel by means of the motor computer 76 electromagnetically. In the in the FIG. 16 shown position, the first input 28 of the pump controller 30 to the tank 14 and the second input 32 of the pump controller 30 to the output 24 is connected. The pump regulator 30 is adjusted in the direction of minimum delivery. In the event of failure of the engine computer 76, the 4/2-way valve 86 at which point the second input 32 of the pump controller 30 is connected to the tank 14 and the first input 28 to the output 24. The pump regulator 30 is adjusted in the direction of maximum delivery.

Claims (15)

1. A feed pump (10) for hydraulic media, comprising an input (12) and an output (16), at the output (16) a feed pressure (P1) being present, a pressure-reducing element (20) that is connected to the output (16), at the output (24) of the element the system pressure (P2) being present and the output (24) being connected to a consumer (26), wherein the output (16) is connected to the first input (28) of a pump controller (30), the second input (32) being connected to the output (24) of the pressure-reducing element (20), and wherein the pump controller (30) adjusts the feed pump (10) toward maximum delivery if the system pressure (P2) is smaller than a minimum pressure (46) or if the system pressure (P2) is smaller than the pressure present at the first input (28), characterized in that parallel to the pump controller (30) a pressure limiter (34) is switched such that at the first input (36) thereof the pressure present at the first input (28) of the pump controller (30) is present and that at the control input (40) the system pressure (P2) is present, the pressure limiter (34) opening if the system pressure (P2) is greater than a desired quantity (42).
2. The feed pump according to claim 1, characterized in that the pressure-reducing element (20) is a filter (22) or the like.
3. The feed pump according to one of the preceding claims, characterized in that the minimum pressure (46) is 1,5 bar to 3 bar, particularly 2 bar, and/or is adjustable during the controlled operation or upon standstill of the controller.
4. The feed pump according to one of the preceding claims, characterized in that the desired quantity (42) is 4 bar to 8 bar, particularly 5,5 bar, and/or is adjustable during the controlled operation or upon standstill of the controller.
5. The feed pump according to one of the preceding claims, characterized in that a regulator (48) is interconnected between the output (16) of the feed pump (10) and the first input (28) of the pump controller (30).
6. The feed pump according to one of the preceding claims, characterized in that a pressure control valve (18) is provided downstream of the output (16) of the feed pump (10), which particularly opens at 9 bar to 15 bar, particularly at 12 bar, and/or at a pressure adjustable during the controlled operation or upon standstill of the controller, e.g. into a tank (14).
7. The feed pump according to one of the preceding claims, characterized in that the system pressure (P2) is present at the second input (38) of the pressure limiter (34) and the open pressure limiter (34) connects the first input (36) to the second input (38).
8. The feed pump according to one of the preceding claims, characterized in that the pressure limiter (34) comprises a second control input (74), wherein particularly the two control inputs (40 and 74) of the pressure limiter (34) are hydraulically connected in series.
9. The feed pump according to claim 8, characterized in that the second control input (74) of the pressure limiter (34) includes a pressure force transmission with respect to the first control input (40).
10. The feed pump according to claim 8 or 9, characterized in that a control valve (72) is provided, which connects the output (24) of the pressure-reducing element (20) to the second control input (74) of the pressure limiter (34), wherein particularly the output (82) of the control valve (72) is connected to the second input (74) of the pressure limiter (34).
11. The feed pump according to claim 10, characterized in that the control valve (72) can be controlled hydraulically and/or electromagnetically and/or via an engine controller (76) of a motor vehicle.
12. The feed pump according to claims 10 or 11, characterized in that a shut-off valve (78) is provided between the output (82) of the control valve (72) and the first control input (40) of the pressure limiter (34).
13. The feed pump according to claim 12, characterized in that the shut-off valve (78) comprises a control input at which the system pressure (P2) is present.
14. The feed pump according to one of the preceding claims, characterized in that a control valve (72), particularly a 4/2-way valve (90), is provided, which connects the second output (32) of the pump controller (30) to the tank.
15. The feed pump according to claim 14, characterized in that the control valve (72) can be controlled hydraulically and/or electromagnetically.

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