GB2369407A

GB2369407A - Valve for controlling liquids, with a central leakage drain

Info

Publication number: GB2369407A
Application number: GB0122611A
Authority: GB
Inventors: Michael Kurrle; Joerg-Peter Fischer
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2000-09-20
Filing date: 2001-09-19
Publication date: 2002-05-29
Anticipated expiration: 2021-09-19
Also published as: FR2814201A1; JP2002155836A; GB2369407B; DE10046662A1; PL349592A1; DE10046662B4; GB0122611D0

Abstract

A valve for controlling liquids has a metering valve for metering a quantity of fuel for injection and a control valve to control the metering valve. A pressurising valve (2) is also provided which undertakes several functions. Firstly, the pressurising valve (2) ensures a constant pressure for the metering valve and routes away any leakage from the metering valve. In addition, the pressurising valve (2) also routes away a leakage from the control valve. In this case, the pressure of the leakage fluid from the control valve is substantially lower than the pressure of the leakage fluid from the metering valve. The pressurising valve according to the invention is designed in such a way here that the two leakage fluids at different pressure levels can be brought together and then drained away in a common leakage line.

Description

Valve for Controlling Liquids with a Central Leakage Drain 10 Prior Art

The present invention concerns a valve for controlling liquids with a central leakage drain. The present invention particularly concerns an injector for a 15 pressure-controlled common rail system.

Injectors of this type generally include a 3/2 way valve as the metering valve for providing a metered quantity of fuel for injection and a solenoid valve to 20 control the metering valve. Leakage flows occur during operation of the injector, both in the metering valve and in the solenoid valve, which have to be drained away. As the metering valve and the solenoid valve work at different pressure levels during operation, a 25 separate leakage line is provided for each of the two valves. Here, the metering valve demonstrates a higher pressure level than the solenoid valve. The two separate leakage lines cannot simply be joined together because the high pressure of the metering valve in 30 comparison with the solenoid valve would otherwise lead to damage, impairment or feedback to the solenoid valve.

Advantages of the Invention In contrast with this, the valve according to the invention for controlling liquids with the 5 characteristics of patent claim 1 has the advantage that it only has one common leak connection for a metering valve and a control valve. A pressurizing valve is provided for this purpose, which has a valve seat, a valve element and a spring element. The 10 pressurising valve serves firstly to generate a constant pressure for the metering valve and secondly to drain a shut-off quantity and/or a first quantity of leaked fluid from the metering valve. The pressurising valve also serves to drain a second quantity of leaked 15 fluid from the control valve. During this, the second quantity of leaked fluid has a lower pressure level than the first quantity of leaked fluid and/or the shut-off quantity. Therefore the pressurising valve according to the invention enables a second quantity of 20 leaked fluid with a different pressure level to be taken up and routed to a common leakage connection.

This results particularly in saving the manufacturing costs for an additional leakage line and the assembly and handling of the valve according to the invention 25 are simplified significantly.

To achieve a defined choke effect, the pressurizing valve preferably has a separate choke device.

Therefore, the choke effect, which is otherwise 30 dependent on the degree to which the valve element of the pressurizing valve is open, can be defined in advance and defined pressure conditions can be achieved. It is particularly to be preferred if the

choke device is arranged in the valve seat before the valve element.

The pressurizing valve preferably has a retaining 5 element to hold and guide the valve element on the valve seat.

This enables the valve element to be held and guided reliably. A central discharge bore is preferably formed in the retaining element. This discharge bore serves to drain away the leakage quantities from the metering valve and the control valve.

The retaining element preferably has a cylindrically shaped region, in which the central discharge bore is formed and which serves to guide the spring element.

In this case, the spring element preferably takes the 20 form of a cylindrical helical spring so that the helical spring is in contact with the cylindrical region of the retaining element and therefore can be guided very effectively.

25 An intake for the second leakage quantity of the control valve preferably opens into the region of the retaining element. This ensures that the cylindrically shaped region of the retaining element, which supports the spring element, is constantly surrounded by fluid, 30 so that the spring element is protected from pressure pulsations which act on the pressurizing valve, because the fluid present around the spring element damps the pulsations. Premature wear on the spring element can

be avoided in this way. To achieve a simple connection between the intake for the second quantity of fluid from the control valve and the central discharge bore, one or more through bores should preferably be formed 5 in the retaining element.

To prevent the valve element being so far from the valve seat that the pressurising valve can no longer close or the valve element can be separated from the 10 retaining element, a stroke limitation is preferably fitted on the retaining element to limit the stroke of the retaining element.

According to a preferred embodiment of the present IS invention, the pressurising valve also contains a guide washer to provide an additional guide for the retaining element and to define a pretensioning of the spring element. 20 The pressurising valve preferably takes the form of a single unit which can be preassembled. This permits the pressurising valve to be tested for function before installation in the valve for controlling liquids.

Furthermore, this modular design permits the 25 pressurising valve to be replaced quickly if functional faults occur for example. Furthermore, this permits specific connection facilities to be provided on the pressurising valve in a simple way depending on the customer's requirements. For example, a thread or a 30 snap fastening can be provided as the connection for the leakage line. An annular groove is provided on the outer circumference of the pressurising valve, which takes the form of a single unit, to permit a simple

connection for the control valve leakage line. The annular groove in turn is then connected via a transverse bore to the actual pressurizing valve.

5 In addition, it should be noted that the control valve preferably takes the form of a solenoid valve and the metering valve preferably takes the form of a 3/2 way valve. 10 Thus a pressurizing valve, particularly for an injector for a common rail system, is proposed according to the invention which is in a position to bring together two flows of leaking fluid of different pressure levels so that only one single leak connection is present on the 15 injector. In addition, the pressurizing valve may be integrated fully into the injector and may.also take the form of.a single unit.

Drawing Several examples of embodiments of the invention are shown in the drawing and are explained in detail in the description which follows. The figures show:

25 Figure 1 a schematic sectional view of a pressurizing valve, which takes the form of a single unit, according to a first example of an embodiment of the present invention; 30 Figure 2 a view showing a part section of the pressurizing valve, shown in figure 1, when installed

Figure 3 a view showing a part section of a pressurizing valve according to a second example of an embodiment of the present invention, when installed, and Figure 4 a view showing a part section of a pressurising valve according to a third example of an embodiment of the present invention, when installed.

Description of the Examples of Embodiments

Figures 1 and 2 show a valve 1 for controlling liquids with a pressurising valve 2 according to the present 15 invention.

As is shown in figure 1, the pressurizing valve 2 takes the form of a compact single unit, which has a connection stub 3 with a connection device 4. As is 20 shown in figure 2, the connection device 4 takes the form of a snap connection in order to permit fast connection of a common pipe to drain away the leaked liquid in the direction of the arrow A. A central mounting bore 5 is formed in the connection stub 3 in 25 which the individual components of the pressurizing valve 2 are arranged.

As is shown in figure 1, the pressurizing valve 2 also includes a valve seat 6, a ball valve 7, a retaining 30 element 8, a cylindrical helical spring 19 and a guide washer 18. The guide washer 18 is arranged in the bore 5 of the connection stub 3 e.g. by means of a

press fit and serves as a spring seat for the helical spring 19.

As is shown in figure 1, the retaining element 8 5 includes a retaining portion 27 for the ball valve 7, a first guide section 9, a second guide section 10 and a cylindrical region 11. The cylindrical region 11 is arranged between the first guide section 9 and the second guide section 10. Two through bores 14 are also 10 formed in the cylindrical region 11. Furthermore, two connection bores 13 are formed close to the retaining region 27 of the retaining element 8. Here, the second guide section 10 is in contact with the inner circumference of the guide washer 18 and the first 15 guide section 9 is guided in-the mounting bore 5 (cf. figure 1). As a result, the retaining element 8 is guided at two points, thus permitting a precise and reliable positioning of the ball valve 7 which is inserted loose.

To prevent the ball valve 7 being raised too far from the valve seat 6 and being removed too far from the retaining element 8 as a result, a stop 23 is formed on the retaining element 8 in the shape of a shoulder to 25 provide a stroke limit for the retaining element 8.

Since the stop 23 comes into contact with the guide washer 18, this limits the stroke of the retaining element 8. It should be noted that both the stroke of.

the retaining element 8 and the pretensioning of the 30 spring element 19 can be adjusted via the selection of the axial thickness of the guide washer 18.

As is particularly apparent from figure 2, leakage from a metering valve (not shown) which meters the quantity of fuel to be injected, and/or a shut-off quantity from the metering valve is routed via the line 21 to the 5 pressurizing valve 2. Here the pressurizing valve 2 ensures that a constant pressure is present at the metering valve. The leakage and/or shut-off quantity from the metering valve is routed in the direction of the arrow B via the line 21 to the pressurizing lO valve 2, as shown in figure 2. During this, the pressurizing valve 2 opens against the force of the spring 19 so that the leakage can be drained away.

As is particularly apparent from figure 1, a further 15 choke device-17 is provided in front of the ball valve 7 as a restrictor to achieve the pressure required in the line 21. In this case, the choke device 17 is formed in the valve seat 6. The leakage of the metering valve is then routed via the two 20 connecting bores 13 to the central discharge bore 12 in the retaining element 8 and is drained onward from there in the direction of the arrow A. A leakage of a control valve (not shown) to control the 25 metering valve is routed via a leakage line 20 in the direction of the arrow C to the pressurizing valve 2, as is shown in figure 2. Here, an annular groove 16 is formed in the connection stub 3, in which connection bores 15 are formed, so that the leakage line 20 is 30 connected to the mounting bore 5. The leakage of the control valve is then also routed to the central discharge bore 12 via the through bores 14, formed in the cylindrical region 11 of the retaining element 8,

and the said leakage is drained away in the direction of the arrow A. Since pressure pulsations often occur during operation 5 of the valve 1 r which also act on the pressurizing valve 2, there is a danger that the helical spring 19 will be damaged. To avoid this, the shut-off quantity from the metering valve is drained away through the central bore 12. A leakage also occurs to avoid a 10 counter-pressure building up in the spring zone on the first guide section 9 between the retaining element 8 and the mounting bore 5, so that here too leakage fluid is routed to the helical spring 19. This guarantees that surges striking the pressurizing valve 2 are 15- damped by the fluid surrounding the helical spring 19.

Furthermore, the helical spring 19 is guided relatively tightly through the cylindrical region 11 of the retaining element 8 so that no twisting/displacement of the helical spring 19 can occur. This provides a 20 further reduction of the risk that the helical spring 19 will be damaged.

As shown in figure 2, the pressurizing valve 2 according to the first example of an embodiment, which 25 takes the form of a single unit, is screwed into a thread 22 in valve 1. To prevent a leakage of fluid outside the system, a sealing ring 24 is provided here between the connection stub 3 of the pressurizing valve 2 and the valve 1. A version with a snap 30 connection would be feasible in this case.

Thus a common line and/or connection 4 is provided for the leakage from the metering valve and from the

control valve, whereby compensation is provided for the different pressure levels of the leakage flows by the pressurizing valve 2. A pressure substantially corresponding to the pressure in the line 20 of the 5 control valve or a lower pressure is then present in the common drain line.

Figure 3 shows a valve 1 for controlling liquids with a pressurizing valve 2 according to the invention, 10 complying with a second example of an embodiment of the present invention. Identical components are designated by the same reference numbers as used in the first example of an embodiment. Since the second example of an embodiment corresponds substantially to the first 15 example, only differences will be described in detail below. Differing from the first example of an embodiment, fin the second example of an embodiment, the connection 20 device 4 of the connection stub 3 takes the form of a thread. That is, a hose or similar, which is joined to the connection stub 3, is attached to the connection stub 3 via the thread 4. Otherwise, the second example of an embodiment corresponds to the first example so 25 that any further description can be dispensed with

below. Figure 4 shows a valve 1 for controlling liquids with a pressurizing valve 2 according to a third example of an 30 embodiment of the present invention. Identical components are designated by the same reference numbers as used in the first example of an embodiment. Since the third example of an embodiment corresponds

substantially to the examples of embodiments described above, only differences will be described in detail below. 5 Unlike the first two examples of embodiments, the pressurizing valve in the third example of an embodiment does not take the form of a single unit but is assembled from individual components and arranged directly within the valve 1. As shown in figure 4, the 10 leakage line 21 from the metering valve is not routed centrally to the pressurizing valve 2. Like the first two examples of embodiments, the choke 17 is again arranged in front of the ball valve 7 in the valve seat 6. Here, the individual parts of the pressurizing 15 valve 2 correspond to the examples of embodiments described previously.

The leakage fluid from the control valve is routed to the central discharge bore 12 of the pressurizing 20 valve 2 via lines (not shown) and the through bore 14.

The central discharge bore 12 is connected via drain lines 26 to a connection stub 25, which is formed on valve 1 for connecting lines (cf. figure 4). In this way a common leakage drain line 26 is provided for the 25 leakage from the metering valve and from the control valve. Otherwise the valve 1 with the pressurising valve 2 according to the third example of an embodiment corresponds to the examples of embodiments described previously so that no further description has been

30 given.

Thus the present invention concerns a valve for controlling liquids which has a metering valve and a

control valve to control the metering valve. In addition, a pressurizing valve 2 is provided, which performs several functions, firstly, the pressurising valve 2 ensures that a constant pressure is present for 5 the metering valve and routes any leakage away from the metering valve. Additionally, the pressurizing valve 2 also routes away any leakage from the control valve.

During this the pressure of the leakage fluid from the control valve is substantially lower than the pressure 10 of the leakage fluid from the metering valve. The pressurizing valve 2 according to the invention is designed such that the two leakage fluids with different pressure levels can be brought together and can then be drained away in a common leakage line.

The above description of examples of embodiments

according to the present invention only serves illustrative purposes and is not intended to restrict the invention. Various amendments and modifications 20 are possible within the scope of the invention without exceeding the scope of the invention and its equivalents.

Claims

5 Claims

1. Valve for controlling liquids, including a metering valve for metering a quantity of fuel for injection, a control valve for triggering the 10 metering valve and a pressurizing valve (2) with a valve seat (6), a valve element (7) and a spring element (19), the pressurizing valve (2) being designed to generate a constant pressure for the metering valve, to drain away a shut-off 15 quantity and/or a first quantity of leaked fluid from the metering valve and to drain away a second quantity of leaked fluid from the control valve, the second quantity of leaked fluid having a lower pressure level than the first quantity of 20 leaked fluid/quantity to be shut off.

2. Valve for controlling liquids according to claim 1, characterized in that the pressurizing valve (2) has a choke device (17).

3. Valve for controlling liquids according to claim 1 or 2, characterized in that the pressurizing valve (2) has a retaining element (8) to hold and guide the valve element (7) on the valve 30 seat (6).

4. Valve for controlling liquids according to claim 3, characterized in that a central

discharge bore (12) is formed in the retaining element (8).

5. Valve for controlling liquids according to claim 5 3 or 4, characterized in that the retaining element (8) has a cylindrically shaped region (11), to guide a spring element (19) taking the form of a cylindrical helical spring.

lO

6. Valve for controlling liquids according to one of the claims 3 to 5, characterized in that an intake (20) for the second quantity of leaked fluid from the control valve opens into the region of the retaining element (8).

7. Valve for controlling liquids according to one of the claims 4 to 6, characterized in that a through bore (14) is formed in the retaining element (8) for a connection between the second 20 quantity of leaked fluid and the central discharge bore (12).

8. Valve for controlling liquids according to one of the claims 3 to 7, characterized in that a stop (23) is provided on the retaining element (8) to limit the stroke of the retain_, element (8).

9. Valve for controlling liquids according to 30 claim 8, characterized in that the pressurizing valve (2) has a guide washer (18) to guide the retaining element (8) and to define the pretensioning of the helical spring (19).

10. Valve for controlling liquids according to one of the claims 1 to 9, characterized in that the pressurizing valve (2) takes the form of a single 5 unit which can be preassembled.

11. Valve substantially as hereinbefore described with reference to Figures 1 and 2 of the accompanying drawings.

12. Valve substantially as hereinbefore described with reference to Figure 3 of the accompanying drawings. 15

13. Valve substantially as hereinbefore described with refernce to Figure 4 of the accompanying drawings.