DE102010064262A1 - Pump, particularly high-pressure pump, for conveying fuel such as diesel fuel, for motor vehicle, has cylinder having inlet and outlet, and another cylinder having another inlet and another outlet - Google Patents

Abstract

The pump has a cylinder (12) having an inlet (16) and an outlet (18), and another cylinder (30) having another inlet (34) and another outlet (36), where an actuating element (48) is also provided. Two pistons (24,42) are provided which are moved in opposite directions. The cylinders are connected to each other by an overflow channel (50). An overflow valve (52) is arranged in the overflow channel. An independent claim is also included for a method for controlling a pump.

Description

The invention relates to a pump, in particular a high-pressure pump for conveying fuel, such as diesel fuel, for a motor vehicle. The invention further relates to a method of controlling a pump, such as a high pressure fuel pump.

Usually, high-pressure pumps are used in motor vehicles as a fuel pump, in particular for diesel fuels, for example in common rail systems, wherein the fuel is compressed to a pressure of about 1 000 to 2 000 bar. For this purpose, for example, phase-angle controlled pumps are realized with electrically operated intake valves. In this case, by keeping the inlet valve open beyond the bottom dead center, into the pumping stroke, the flow rate can be controlled.

However, such a solution is generally preferable, especially for reasons of cost, only for single-piston pumps, as in multi-piston pumps, such as already in two-piston pumps, a separate often costly electrical valve with a mostly electromagnetic actuator is necessary for each cylinder.

It is the object of the invention to provide a pump and a method for controlling a pump, with the aid of which, even with a multi-piston pump, a cost-effective control of the flow rate is possible even for large flow rates.

The object is achieved by the subject matters of the independent claims.

In this case, a pump, in particular a high-pressure pump for conveying fuel, such as diesel fuel for a motor vehicle, comprises a first cylinder having a first inlet and a first outlet and in which a first piston is movably arranged, and a second cylinder a second inlet and a second outlet, and in which a second piston is movably arranged, wherein at least one actuating means is provided, through which the first piston and the second piston are movable in opposite directions, wherein the first cylinder and the second cylinder through an overflow channel are connected to each other, and wherein in the overflow an overflow valve is arranged.

The pump has a first and a second cylinder, each having an inlet and an outlet, and in each case one in the cylinder movably arranged piston. Consequently, the pump may be a two-chamber pump or two-piston pump. However, the pump may also have more than two chambers, for example, four or eight chambers, as will be apparent to those skilled in the following. As a result, very high flow rates are possible, which makes it possible to apply the pump even with large or high-displacement engines. Thus, even with such engines, the Digitalansteuertechnik possible what previously was not possible by the relatively small volume of single-piston pumps.

Furthermore, use is also possible in high-pressure systems, that is both in diesel, and in gasoline-powered vehicles, which brings a standardization of the control electronics and the control functionality with it. This makes it possible to use the described pump within the framework of a modular system. High pressure applications according to the invention are in particular in a range of more than 1 000 bar.

For actuating the pump, at least one actuating means is provided by which the first piston and the second piston are movable in opposite directions. In this case, an actuating means can be provided for each piston. However, particularly preferably, an actuating means can move both the first and the second piston in the cylinder. In this case, an opposite movement of the piston is important according to the invention. This means that when a medium, such as fuel, flows into the first cylinder, the medium is pressed out of the second cylinder at the same time, and vice versa. Therefore, the pump and suction cycle of the first piston and the second piston are exactly offset.

In this case, furthermore, the first cylinder and the second cylinder are connected to one another by an overflow channel. As a result, the medium to be pumped can not only be pumped to the high-pressure application, for example into the engine cylinder, but also direct pumping of the medium from the first cylinder into the second cylinder, and vice versa, can take place. In order to regulate this overflow or to control the direction of the overflow, an overflow valve is arranged in the overflow channel.

The pump described is thus particularly suitable to safely and accurately control the flow rate even at high flow rates. The pump according to the invention is very inexpensive in construction.

In a preferred embodiment of the invention, the at least one actuating means is an eccentric, by means of which the first piston and the second piston are movable in opposite directions. This embodiment is very cost-effective, since the opposite movement of the first and the second piston can be realized with only one actuating means. An opposite movement of the first and second pistons can be reliably ensured. In addition, an eccentric is a very simple actuator, which is less susceptible to damage and thus increases the long-term stability and reliability of the pump according to the invention. Furthermore, with an eccentric and large forces can be transmitted, so that the pump according to the invention is also suitable for high pressure applications, such as for conveying fuel in a common rail injection system. A preferred arrangement of the first and the second piston is an arrangement corresponding to a boxer engine.

Particularly preferably, it is further provided that the overflow valve has a valve chamber having a main chamber which is connected to a first opening and a second opening, wherein the first opening with the first cylinder and the second opening is connected to the second cylinder, and wherein the first opening and / or the second opening with respect to the main chamber is closable. The overflow valve thus has a valve chamber with a main chamber, wherein in addition to the main chamber still additional secondary chambers may be provided. Depending on the design of the overflow valve or field of application of the pump according to the invention, however, the valve chamber may consist only of the main chamber. Characterized in that the main chamber is connected to a first opening and a second opening, wherein the first opening with the first cylinder and the second opening is connected to the second cylinder, a free passage of the conveyed through the overflow medium through the spill valve can be realized. In this case, an almost unhindered exchange of medium, such as fuel, between the first cylinder and the second cylinder is possible. However, by virtue of the fact that the first opening and / or the second opening can be closed with respect to the main chamber, the free exchange of the medium between the first cylinder and the second cylinder can be prevented. In this case, therefore, no medium can be conveyed, for example, from the first cylinder to the second cylinder, whereby all the medium pumped by the first or the second cylinder flows exclusively from the first and the second outlet.

In a further preferred embodiment of the invention it is provided that the overflow valve has a first sealing seat for a sealing element for closing the first opening with respect to the main chamber and a second sealing seat for a sealing element for closing the second opening with respect to the main chamber. In this way, both overflow directions can be selectively closed by the overflow valve. Thus, a delivery of a medium is selectively only from the first piston to the second. Piston, or vice versa from the second piston into the first piston possible, in which case the opposite direction is locked. This can be possible in particular in that the sealing element and the sealing seat are formed to form a check valve, that is to form a blocking position in one direction, whereas the other direction is free. Since the first and the second piston in the first and the second cylinder are movable in opposite directions, a complete closing of the overflow valve, so a lock in both Überströmrichtungen, not mandatory, since pressure only from a cylinder and therefore into one of the openings of the valve chamber can be built.

In a further advantageous embodiment of the present invention, it is provided that the position of the sealing element is substantially adjustable by the energization or Entstromung a coil, wherein the coil interacts with a magnetic or magentisable cooperating with the sealing element body, and wherein the sealing element is spring preloaded. In this way, a particularly simple control of the overflow valve is possible. Due to the spring preload, the sealing element is already pressed into a sealing seat. When the coil is blasted, the magnetic or magnetizable body moves against the force of the spring and into the opposite sealing seat. When the coil is de-energized, the sealing element is returned to its original position. An interaction of the magnetic or magnetizable body with the sealing element, as well as a Federvorbelastung, for example via valve rods. The fact that the position of the sealing element can be adjusted essentially by the energization or de-energization of a coil means that the sealing element is displaced into the region of the sealing seat or loosely into the sealing seat. The actual sealing effect is achieved by the pressure of the inflowing medium, which presses the sealing element firmly into the sealing seat.

It is preferred if the sealing seat is configured funnel-shaped, wherein the sealing element is a sealing ball. This is a particularly simple and therefore cost-effective design, which makes the production of the pump described above particularly cost. In addition, this design is not susceptible to damage. This further improves the reliability of the overflow valve and thus of the pump.

The invention further relates to an internal combustion engine, as well as a motor vehicle comprising at least one pump as described above and further developed. With the help of the pump is also at one Multi-piston pump and even with large flow rates cost control of the flow possible.

The invention further relates to a method for controlling a pump as described above and further developed, in particular a high-pressure pump for conveying fuel, such as diesel fuel, for a motor vehicle, wherein the delivery rate of the pump is controlled by opening and / or closing the spill valve. An opening and / or closing means an opening and / or closing, ie a blocking position or a passage position of the overflow valve with respect to the piston or cylinder, which is in a pumping cycle. In this case, by controlling the overflow valve, the desired flow rate can be adjusted continuously. If the overflow valve is closed, ie if no medium can pass through the overflow valve, all the medium from the corresponding cylinder is pumped out of the respective outlet by the piston. As a result, the entire medium of the desired application is supplied, which corresponds to a full funding. If, in contrast, the overflow valve is opened, so that medium can be pumped out of the first cylinder through the overflow valve into the second cylinder, no delivery to the desired application takes place. Because the fact that the first piston and the second piston are movable in opposite directions, the cylinder volume of the first cylinder decreases to the same extent as the cylinder volume of the second cylinder increases. Therefore, it is easy to pump medium from the first cylinder to the second cylinder. In this case, a zero promotion takes place. If, on the other hand, the overflow valve and thus the overflow channel with respect to the respective piston movement or to the pumping phase of the respective piston are open to 50% of the pumping phase, 50% of the cylinder contents are overflowed. The collecting cylinder is filled, for example, the first 50% of the suction phase by overflow, and the second 50% of the suction phase through the inlet valve. By a suitable adjustment of the opening time of the overflow in the respective pumping phase can thus be adjusted in a simple manner, the flow rate of 0%, ie a zero flow up to a flow rate of 100%, ie a full promotion.

In a preferred embodiment of the method, the opening and / or closing of the overflow valve is triggered by a displacement of a sealing element in a sealing seat or from a sealing seat. In this way, only one sealing element is necessary, which is perfectly sufficient for an opposite movement of the piston. It is also sufficient to shift the sealing element loose in a sealing seat. The actual sealing effect can be achieved by pressing the medium from the respective piston through the overflow channel into the overflow valve, whereby the sealing element is pressed into the sealing seat with great force. This makes a particularly simple and reliable sealing effect possible.

It is further preferred that the displacement of the sealing element takes place by energizing or out-currenting a coil, wherein the coil interacts with a magnetic or magentisable cooperating with the sealing element body, and wherein the sealing element is spring-loaded. The interaction can take place in such a way that the magnetic or magnetizable body, which can interact with a valve rod, is moved by energizing or out-currenting the coil. As a result, the valve rod can be displaced against the spring force. In the case of an outflow, the valve rod and thus the body can be displaced into the coil by the spring force. This is a particularly simple way to relocate the sealing element, whereby the inventive method is particularly simple and inexpensive executable.

The invention will be explained by way of example with reference to the accompanying drawings based on preferred embodiments.

Show it:

1 a schematic sectional view of a pump;

2 a schematic sectional view of a spill valve for a pump in a first blocking position;

3 a schematic sectional view of a spill valve for a pump in a second locking position; and

4 : a schematic representation of a method according to the invention.

In 1 is a pump 10 shown according to a possible embodiment of the invention. The pump 10 is particularly suitable for high pressure applications. For example, the pump 10 arranged in a common rail injection system of an internal combustion engine in a motor vehicle.

The pump 10 includes a first cylinder 12 for example, in a first cylinder housing 14 can be arranged. The cylinder 12 or the cylinder housing 14 conveniently has a first inlet 16 and a first outlet 18 through, for example, a Liquid, such as fuel, into the first cylinder 12 is on or ausbringbar. The inlet 16 as well as the outlet 18 is preferably through a first inlet valve 20 or by a first outlet valve 22 closed fluid-tight. The inlet valve 20 as well as the exhaust valve 22 , may be particularly preferably designed as a ball valve. Further, a first piston 24 provided, at least partially in the first cylinder 12 is arranged and is movably arranged there, within the first cylinder 12 To reduce or increase existing volume and so, for example, to start a pumping cycle. In this case, the first piston 24 a preferably circumferential sealing surface 26 on, with the first cylinder 12 along with its inner wall 28 or with the inner wall of the first cylinder housing 14 is sealed fluid-tight.

The pump 10 further comprises a second cylinder 30 for example, in a second cylinder housing 32 can be arranged. The second cylinder 30 or the second cylinder housing 32 can thereby according to the first cylinder 12 or the first cylinder housing 14 be educated. Consequently, the second cylinder 30 or the second cylinder housing 32 expediently a second inlet 34 and a second outlet 36 through, for example, a liquid, such as fuel, in the second cylinder 30 is on or ausbringbar. The second inlet 34 as well as the second outlet 36 , is preferably through a second inlet valve 38 or by a second outlet valve 40 closed fluid-tight. The inlet valve 38 as well as the exhaust valve 40 , may be particularly preferably designed as a ball valve. Further, a second piston 42 provided, at least partially in the second cylinder 30 is arranged and arranged to be movable there, within the second cylinder 30 To reduce or increase existing volume, and so for example to start a pumping cycle. In this case, the second piston 42 a preferably circumferential sealing surface 44 on, with the second cylinder 30 along with its inner wall 46 or with the inner wall of the second cylinder housing 32 is sealed fluid-tight.

Preferably between the first piston 24 and the second piston 42 can be an actuating means 48 be provided by the first piston 24 and / or the second piston 42 are movable in opposite directions. For example, the actuating means 48 to be an eccentric. This ensures that at one by the actuator 48 triggered displacement of the first piston 24 and the second piston 42 the first piston 24 into the interior of the first cylinder 12 is displaced, whereas the second piston 42 towards the outside of the second cylinder 42 relocated. Therefore, compression occurs in the first cylinder 12 at the same time a depression in the second cylinder 42 instead, and vice versa.

It is further contemplated that the first cylinder 12 with the second cylinder 30 connected is. This is an overflow channel 50 intended. Conveniently in the overflow 50 is an overflow valve 52 arranged, which is the overflow 50 close fluid-tight or can open.

A preferred embodiment of a pump according to the invention 10 usable overflow valve is in the 2 and 3 shown. It will be in the 2 and 3 corresponding components provided with the same reference numerals.

According to 2 is the overflow valve 52 designed as a double ball valve. The overflow valve 52 can therefore be a valve body 54 include, in which a valve chamber 56 is arranged. The valve housing 54 has a first opening 58 and a second opening 60 on, with which the valve chamber 56 connected is. Through the first opening 58 and the second opening 60 is the valve chamber 56 the overflow valve 52 with the overflow channel 50 fluidly connected. For example, the first opening 58 with the first cylinder 12 connected, whereas the second opening 60 with the second cylinder 30 connected is. To the overflow valve 52 to open or close, is a sealing element 62 provided, which may be formed, for example, as a sealing ball. On the opposite sides of the sealing element 62 can each have a valve stem 64 . 66 be arranged. The valve rod 64 For example, a magnetic or magnetizable body 68 show that in a coil 70 is arranged. The sealing element 62 can stand up against a spring 72 support the valve stem 66 and thus the sealing element 62 in the direction of the coil 70 biases. By energizing the coil 70 can the body 68 by electromagnetic forces in the direction of the coil 70 and thus against the spring force of the spring 72 be pressed.

According to 2 has the overflow valve 52 , or the valve chamber 56 , a main chamber 74 , a first secondary chamber 76 and a second side chamber 78 on. The first opening 58 can in the first secondary chamber 76 and the second opening 60 in the second secondary chamber 78 be arranged. In this case, the overflow valve 52 a first sealing seat 80 for the sealing element 62 for closing the first opening 58 with reference to the main chamber 74 and a second sealing seat 82 for the sealing element 62 for closing the second opening 60 with reference to the main chamber 74 on. The main chamber 74 For example, with the first secondary chamber 76 over the first seal seat 80 be connected, the main chamber 74 with the second secondary chamber 78 over the second sealing seat 82 can be connected. In particular, when the sealing element 62 is a sealing ball, the sealing seat can 80 . 82 be funnel-shaped. As a result, the sealing ball sets in the energized coil by the spring force of the spring 72 against the first seal seat 80 so that essentially the first opening 58 is closed. This condition is in 2 shown.

Will the coil 70 on the other hand energized, so a current flows through the coil, is the magnetic or magnetizable body 68 in the direction of the coil 70 displaces and thus presses the valve stem 66 against the spring force of the spring 72 so that the sealing element 62 against the second sealing seat 82 is pressed. This essentially becomes the second opening 60 locked. This condition is in 3 shown.

The 2 and 3 thus show the essential operating conditions of the overflow pump 52 , which thus serves a digital control technique.

In 4 is the inventive method for controlling the pump 10 shown. In 4 the piston movements of the first cylinder and the second cylinder are shown. OT designates the top dead center of the piston, ie the beginning of a pump cycle, whereas UT denotes the bottom dead center of the piston, ie the end of a pump cycle.

Out 4 it will be seen that with respect to the first cylinder 12 when it is at the bottom dead center, and therefore starts a pumping cycle, a delivery rate of 100%, ie a full delivery, takes place when in a time to top dead center, the spill valve 52 with respect to the pumping direction of the first cylinder 12 is open (area A). On the other hand, is the overflow valve 52 opened when the first cylinder 12 moved from its top dead center to its bottom dead center (area B), so runs a suction cycle, there is a zero promotion, ie a promotion rate of 0% instead. Accordingly, a 50% delivery rate can be set if the spill valve is opened exactly half the time that the piston is displaced from bottom dead center to top dead center (region C).

Consequently, the delivery rate of the pump can be controlled by opening and / or closing the spill valve.

LIST OF REFERENCE NUMBERS

10

pump

12

first cylinder

14

first cylinder housing

16

first inlet

18

first outlet

20

first inlet valve

22

first exhaust valve

24

first piston

26

sealing surface

28

inner wall

30

second cylinder

32

second cylinder housing

34

second inlet

36

second outlet

38

second inlet valve

40

second exhaust valve

42

second piston

44

sealing surface

46

inner wall

48

actuating means

50

overflow

52

overflow

54

valve housing

56

valve chamber

58

first opening

60

second opening

62

sealing element

64

valve rod

66

valve rod

68

body

70

Kitchen sink

72

feather

74

main chamber

76

secondary chamber

78

secondary chamber

80

first sealing seat

82

second sealing seat

Claims (10)

Pump, in particular high-pressure pump for conveying fuel, such as diesel fuel, for a motor vehicle, comprising a first cylinder ( 12 ), which has a first inlet ( 16 ) and a first outlet ( 18 ), and in which a first piston ( 24 ) is movably arranged, and a second cylinder ( 30 ), which has a second inlet ( 34 ) and a second outlet ( 36 ), and in which a second piston ( 42 ) is arranged movable, wherein at least one actuating means ( 48 ) is provided, through which the first piston ( 24 ) and the second piston ( 42 ) are movable in opposite directions, wherein the first cylinder ( 12 ) and the second cylinder ( 30 ) by an overflow channel ( 50 ) are connected to each other, and wherein in the overflow channel ( 50 ) an overflow valve ( 52 ) is arranged. Pump according to claim 1, characterized in that the at least one actuating means ( 48 ) is an eccentric, through which the first piston ( 24 ) and the second piston ( 42 ) are movable in opposite directions. Pump according to claim 1 or 2, characterized in that the overflow valve ( 52 ) a valve chamber ( 56 ) with a main chamber ( 74 ) having a first opening ( 58 ) and a second opening ( 60 ), the first opening ( 58 ) with the first cylinder ( 12 ) and the second opening ( 60 ) with the second cylinder ( 30 ), and wherein the first opening ( 58 ) and / or the second opening ( 60 ) with reference to the main chamber ( 74 ) is closable. Pump according to claim 3, characterized in that the overflow valve ( 52 ) a first sealing seat ( 80 ) for a sealing element ( 62 ) for closing the first opening ( 58 ) with reference to the main chamber ( 74 ) and a second sealing seat ( 82 ) for a sealing element ( 62 ) for closing the second opening ( 60 ) with reference to the main chamber ( 74 ) having. Pump according to one of claims 1 to 4, characterized in that the position of the sealing element ( 62 ) essentially by the energization or derusting of a coil ( 70 ) is adjustable, the coil ( 70 ) with a magnetic or magentisable with the sealing element ( 62 ) cooperating body ( 68 ) interacts, and wherein the sealing element ( 62 ) is spring preloaded. Pump according to claim 4, characterized in that the sealing seat ( 80 . 82 ) is funnel-shaped, wherein the sealing element ( 62 ) is a sealing ball. Motor vehicle comprising at least one pump ( 10 ) according to one of claims 1 to 6. Method for controlling a pump ( 10 ) according to one of claims 1 to 5, in particular a high-pressure pump for conveying fuel, such as diesel fuel, for a motor vehicle, wherein the delivery rate of the pump ( 10 ) by opening and / or closing the overflow valve ( 52 ) is controlled. A method according to claim 8, characterized in that the opening and / or closing of the overflow valve ( 52 ) by displacing a sealing element ( 62 ) in a sealing seat ( 80 . 82 ) or from a sealing seat ( 80 . 82 ) is triggered out. A method according to claim 9, characterized in that the displacement of the sealing element ( 62 ) by energizing or derusting a coil ( 70 ), the coil ( 70 ) with a magnetic or magentisable with the sealing element ( 62 ) cooperating body ( 68 ) interacts, and wherein the sealing element ( 62 ) is spring preloaded.

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