WO2009130068A1

WO2009130068A1 - Compact injection device having a flat armature air adjuster

Info

Publication number: WO2009130068A1
Application number: PCT/EP2009/051278
Authority: WO
Inventors: Walter Maeurer
Original assignee: Robert Bosch Gmbh
Priority date: 2008-04-23
Filing date: 2009-02-04
Publication date: 2009-10-29
Also published as: DE102008001331A1; TW201002936A; CN102016286B; TWI484094B; CN102016286A

Abstract

The present invention relates to an injection device, comprising a fuel pump (20a), a pressure regulator (20b), an injector (20c), and an air adjuster (20d), characterized in that the fuel pump (20a), the injector (20c), and the air adjuster (20d) are integral parts of an injection module (2), the pressure regulator (20b) is an integral part of the injector (20c), the fuel pump (20a) comprises a piston (26), a pump armature (22), and a pump chamber (31), the air adjuster (20d) comprises a valve seat (54, 55) and a flat armature (23), and the pump armature (22) and the flat armature (23) can be activated by means of a mutual coil (21).

Description

description

title

Compact injection device with flat anchor air actuator

State of the art

The present invention relates to an injection device with a fuel pump, a pressure regulator, an injector and an air actuator in a compact design.

Injectors are known in the prior art in various configurations. Especially for cost and space reasons require small internal combustion engines, which have only one or only two cylinders and a small displacement, independent solutions. Areas of use of such small internal combustion engines are, for example, two-wheelers or tricycles or lawnmowers, etc. Known injectors usually comprise in a tank a fuel pump with a pressure regulator, the fuel pump injecting fuel at a predetermined pressure into a duct, e.g. a rail or similar, promotes. At the end of the line, an injector is arranged, which, controlled by a control device, injects fuel into a suction pipe or directly into a combustion chamber. However, such injection devices are very expensive and particularly expensive, so that they also make small internal combustion engines very expensive.

From EP 1 340 906 B1 a fuel injection device with electronic control is known in which an injector is arranged close to a pump piston. Further, in this case, a pre-pressure valve is provided for exerting an admission pressure on the fuel in an initial phase of a pressure stroke of the piston in the return line of the fuel to the tank. The admission valve evacuates a part of the fuel located in a pressure chamber in the return line. In this way, in particular the formation of vapor bubbles in the injector can be reduced. However, the structure is relatively complicated and the device takes up a large amount of space.

Advantages of the invention

The injection device according to the invention with the features of claim 1 has the advantage that it has a very compact structure. Furthermore, the injection device according to the invention can be produced in a particularly simple and cost-effective manner. According to the invention, the injection device comprises a fuel pump, a pressure regulator for Control of an injection pressure, an injector and an air actuator, which are integral parts of an injection module. The injection module is a compact, small-sized component. The pressure regulator is an integral part of the injector. In addition to the injection module, the injection device according to the invention further comprises a fuel supply line, a fuel return line and an air bypass line. The fuel pump comprises a piston, a pump anchor and a pump chamber in which fuel can be pressurized. The air actuator comprises a valve seat and a flat anchor. The pump anchor and the flat armature can be actuated by means of a common coil, so that a common actuator with only one electrical connection can be provided for the air actuator and the fuel pump. The injection module can be completely pre-assembled so that it only needs to be connected to the necessary connections and can be installed directly into a vehicle. The components of the injection module are preferably arranged in a common housing of the injection module. In addition to the compactness of the injection module is another great advantage that other components for the injection module can be minimized.

The dependent claims show preferred developments of the invention.

Particularly preferably, the pump armature of the fuel pump is annular and a return path for fuel from the injection module back to the tank passes through the annular pump armature. As a result, a particularly compact construction of the injection module is achieved and, furthermore, heat can be removed from the injection module into the tank by the return of the fuel through the pump anchor. Furthermore, a flow through the pump armature with only a slight pressure loss is possible. More preferably, the annular pump anchor is arranged substantially vertically, so that any existing gas bubbles in the fuel can rise through the pump anchor and can be vented into the tank. Since the fuel is heated when flowing through the pump armature due to the absorbed waste heat of the solenoid, outgassing from the heated fuel is enhanced. This circulation of fuel also ensures that cooler fuel is always supplied to the injection module.

More preferably, the flat armature of the Luftstellers is annular. This can ensure that the magnetic field lines enter and exit axially into the flat armature. Furthermore, the annular flat armature also makes it possible to guide the fuel inside the flat armature centrally through the injection module. Preferably, the air actuator on three passage openings, which are formed partially ring-shaped or kidney-shaped. At the edge of the passage openings, sealing surfaces are formed in the form of either two concentric annular sealing surfaces or by providing a bead region provided along the circumference of each of the passage openings. Through these sealing surfaces is at a small stroke a relatively large Released area, so that a large amount of air can be provided with a relatively small Öffhungshub.

Particularly Favor runs a return path for fuel also through the annular flat armature. In this way, where appropriate, there resulting heat can be dissipated and the injection module can have a particularly compact design.

According to a further preferred embodiment of the present invention, the flat armature is fixed by means of a return spring to a housing of the injection module. The return spring is preferably an annular plate spring which fixes the flat armature on the housing.

Preferably, a connection passage between the pump space and a suction space in the axial direction of the pump piston is arranged below a top dead center of the pump piston. This ensures that at the beginning of a pressure build-up phase of the fuel pump in the pump chamber can not be built immediately pressure and any existing gases through the

Connecting passage can be pushed out of the pump chamber into the suction. Furthermore, the pump piston can be accelerated quickly to its target speed, since at the beginning of the pressure build-up phase, only a small hydraulic counterforce is present through the fuel. When the connecting passage is then closed by the piston, the actual pressure build-up phase begins in the pump chamber.

In order to provide a design which is as simple and inexpensive as possible, the connection passage between the pump space and the suction space is preferably arranged in a lower annular channel area of the suction space. More preferably, a filter element is arranged between the lower annular channel region and a main region of the suction chamber. In this way it can be ensured that only the amount of fuel sucked into the pumping chamber is filtered and that it is not necessary to filter the entire quantity of fuel supplied into the intake chamber. Thus, the circulating part of the fuel is not filtered and a longer shelf life of the filter is achieved.

According to an alternative embodiment of the present invention, the pump piston has a recess which extends on the outer circumference of the pump piston up to a pressure surface of the pump piston directed to the pump chamber. The recess establishes a connection between the pump chamber and the suction chamber at the beginning of a pressure build-up phase of the fuel pump and after a predetermined stroke away from the pump piston, the connection is interrupted via the recess. The recess is preferably a longitudinal groove in the piston and thus provides a slot control during pressure buildup in the pumping space. - A -

More preferably, a cylinder for the pump piston is integrally formed on the housing of the injection module. This achieves a further simplification and cost reduction of the injection device. The cylinder may e.g. to be a liner.

Furthermore, the present invention relates to an internal combustion engine which comprises exactly one cylinder or exactly two cylinders and a fuel injection device according to the invention. Particularly preferably, the internal combustion engine comprises a fuel tank, which is arranged above the injection module. As a result, in particular, the fuel pump can be designed very small.

drawing

Hereinafter, a preferred embodiment of the invention will be described in detail with reference to the accompanying drawings. In the drawing is:

1 shows a schematic view of a small motor with an injection device according to a first embodiment of the invention,

Figure 2 is a schematic view of an injection module of the injection device according to the first

3 shows a schematic plan view of a sealing seat of the air regulator,

FIG. 4 shows a schematic sectional view along the line IV-IV of FIG. 3,

FIG. 5 shows a schematic plan view of an alternative sealing seat,

Figure 6 is a schematic sectional view taken along the line VI-VI of Figure 5, and

Figure 7 is a schematic view of an injection module of the injection device according to a second embodiment of the invention.

Preferred embodiments of the invention

Hereinafter, a small motor 1 with an injection device according to the invention according to an embodiment will be described in detail with reference to Figures 1 to 4.

Figure 1 shows schematically the structure of the small motor 1, which is designed as a single-cylinder engine. The small engine 1 comprises a cylinder 3, a reciprocating piston 4, a control unit 5 and a tank 6. The tank 6 is connected to an injection module 2 via a fuel supply line 6a. A fuel return line 6b goes from the injection module 2 back to the tank 6. As can be seen schematically from FIG. 1, the tank 6 is arranged above the injection module 2. As a result, the fuel passes through the fuel supply line 6a due to gravity to the injection module 2. The injection module 2 is shown very schematically and includes a fuel pump, an injector with integrated pressure regulator, and an air actuator, so that the injection module 2 is very compact.

The small engine 1 further comprises a throttle valve 7, which is arranged in a suction pipe 8. On the cylinder 3, a spark plug 9, an intake valve 10 and an exhaust valve 11 are further arranged. The reference numeral 12 designates a bypass line for air, which branches off air from the intake manifold 8 from a region in the flow direction of the air in front of the throttle valve 7 and leads directly to the integrated into the injection module 2 air actuator. An outlet 12z of the bypass line 12 opens in the intake manifold 8 behind the throttle valve. 7

The small engine 1 further comprises an exhaust pipe 13, which is released or closed by the exhaust valve 11. Further, an oxygen sensor 14 is provided on the exhaust pipe 13, which is connected to the control unit 5, and the control unit 5 is further comprising a cooling water sensor 15, an oil temperature sensor 16 and a sensor unit 17 for detecting a throttle position, a temperature in the intake manifold 8 and a Pressure in the suction pipe 8 connected. The control unit 5 controls the injection module 2 on the basis of the received signals.

The injector according to the invention thus comprises the injection module 2 with a fuel pump, a pressure regulator, an injector and an air actuator and a

Fuel supply line of a fuel return line and an air bypass connection, and can be designed to be particularly compact and compact. Furthermore, the injection device according to the invention can be produced very inexpensively and in particular be pre-assembled in advance as a complete injection module, so that it only needs to be installed in the small engine 1 as a compact assembly. The integration of the four items fuel pump, pressure regulator, injector and air actuator in the injection module thus a simple and inexpensive manufacturability is guaranteed. The fuel pump and the air actuator are actuated by a common actuator. As a result, the injection device 2 according to the invention can be used, for example, in small engines of two-wheelers or lawnmowers.

FIG. 2 shows the injection module 2 in detail. In the injection module 2, the fuel pump 20a, the pressure regulator 20b, the injector 20c and the aerator 2Od are integrated. For this purpose, a housing 25 is provided, which is injection molded from plastic. The pressure regulator 20b is part of the injector 20c. A common actuator simultaneously actuates the fuel pump 20a and the aerator 2Od. The common actuator comprises a coil 21, a pump armature 22 and a flat armature 23 for the air actuator. The housing 25 is closed by means of a cover 24. As can be seen from Figure 2, the pump armature 22 is annular and has a cylindrical shape. In the pump armature 22, a passage 22a is thus formed, through which fuel can flow from the fuel supply line 6a to the fuel return line 6b. The coil 21 is provided with a plastic extrusion 21 a and is surrounded by a magnetic circuit 40. Reference numerals 41 and 42 denote a first magnetic separation point and a second magnetic separation point, respectively. An electrical connection 44 for the coil 21 is formed laterally on the housing 25.

In addition to the pump armature 22, the fuel pump 20b also comprises a cylindrical piston 26 and a cylindrical bushing 35. The piston 26 is guided in the bushing 35. A first return spring 27 brings the piston into the starting position shown in Figure 2, which represents one end of a suction stroke. To support the first return spring 27, an annular flange 26 a is formed on the piston 26. The piston 26 is connected via a bracket 31 with the annular pump armature 22. The bracket 31 may be arranged loosely between the pump armature 22 and the piston 26 or be connected to one or both parts. At its other end, the first return spring 27 is supported on an inner annular flange region 25c of the housing 25 (see FIG.

The injection module 2 further comprises a suction chamber 30, in which the fuel supply line 6a opens. In the suction chamber 30 and the fuel pump 20a is arranged. The suction space 30 includes an annular channel portion 30 a which is disposed at a lower portion of the suction space adjacent to the annular flange portion 25 c of the housing 25. The annular channel region 30a is separated from the remaining suction chamber 30 by means of a filter 37.

The fuel pump 20a further includes a pumping space 29 in which fuel can be pressurized to be injected into the suction pipe 8 via the injector 20c. The injector 20c is disposed at one end of the injection means and integrally includes the pressure regulator 20b of the injection module. The pressure regulator 20b comprises a metering throttle 32 and a check valve 33, which is prestressed by means of a third return spring 34. The third return spring 34 is supported on a support ring 38, which is fixed to the housing 25.

As can be seen in FIG. 2, the aerator 2Od comprises a flat armature 23, a sealing seat 43 and an air-filled space 45. The flat armature 23 is fixed to the housing 25 by means of a second restoring spring 28, which in this embodiment is an annular flat spring. The second return spring 28 may, for example, between the housing 25 and the cover 24 by means

Clamps are fixed. The sealing seat 43 is shown in more detail in FIGS. 3 and 4. In the sealing seat 43 while three part-annular openings 51, 52, 53 are formed. The openings 51, 52, 53 are here bounded on the inside by a protruding inner ring 54 and on the outside by a protruding outer ring 55. The inner ring 54 and the outer ring 55 thereby form the actual sealing surface on which the flat armature 23 seals. The areas between the openings 51, 52, 53 are slightly lower than the sealing surface on the inner ring 54 and the outer ring 55, so that the entire ring cross-section between the inner ring 54 and outer ring 55 during the opening of

Flat anchor 23 is released. As can be seen from FIG. 2, the air-filled space 45 is arranged below the flat armature 23, which ensures an opening movement of the flat armature 23 when the coil 21 is energized.

Between the suction chamber 30 and the pump chamber 29, a connection passage 36 is further provided. In this case, the connection passage 36 opens in particular in the annular channel area 30a of the suction space 30. The connecting passage 36 comprises an opening 35a in the bushing 35 and an opening 25b in the annular flange area 25c of the housing 25. In the axial direction XX of the injection module, the connection passage 36 is slightly below an upper one Dead center of the piston 26. In this way, a slot control for the pressure build-up in the pump chamber 29 is obtained, since a pressure build-up in the pump chamber 29 only occurs when the piston 26 has completely overpassed the connection passage 36 and the connection passage is closed by a side wall of the piston 26. A pressure surface 26b of the piston 26 directed to the pumping space 29 forms the control edge.

The function of the injection module according to the invention is as follows. Figure 2 shows a position of the piston at the end of a suction stroke. In this state, the coil 21 is energized, so that on the one hand the flat armature 23 is moved in the direction of arrow A and the annular pump armature 22 is moved in the direction of arrow B. It should be noted that, depending on a current strength, it is also possible that only the flat armature 23 is moved, so that the air actuator opens 2Od, the fuel pump 20a is not actuated. However, if the amperage is sufficient, the air actuator 2Od and the fuel pump 20a are simultaneously actuated, so that on the one hand the flat armature 23 is moved and on the other hand the annular pump armature 22 is moved in the direction of the arrow B. As a result, the piston 26 is moved over the bracket 31 in the direction of arrow B. At the beginning of the pressure stroke, however, there is still no pressure build-up in the pump chamber 29, since the piston 26 has not yet crossed over the connection passage 36. Only when the piston 26 has completely crossed over the connection passage 36, the pressure build-up in the pump chamber 29 begins. Once a sufficient pressure in the pump chamber 29 is reached, the check valve 33 opens against the force of the return spring 34. This allows fuel from the pump chamber 29 via the orifice throttle 32 are injected into the suction pipe 8. A regulation of the pressure height of

Injection takes place via the choice of the diameter of the metering throttle 32 and the spring force of the third return spring 34. As soon as the pressure in the pump chamber 29 again below the Öffhungsdruck decreases, the third return spring 34, the check valve 33 back to the starting position, in which the check valve 33 rests against an integrally formed on the housing 25 valve seat 25a and the pump chamber 29 closes. Thus, the injection of fuel is stopped and energization of the coil 21 can also be stopped. Then, the first return spring 27, the piston 26 back to the starting position, wherein on the bracket 31 and the annular pump armature 22 is reset. As soon as the piston 26 has crossed over the connection passage 36, an intake of fuel from the annular channel area 30a into the pumping space 29 begins. Since the suction takes place only from the annular channel area 30a, only the actually aspirated fuel has to be filtered through the filter 37. As a result, the filter 37 has a very long life.

Since the pump armature 22 is thus pierced axially, fuel can freely flow through the pump armature 22 from the fuel supply line 6a to the fuel return line 6b via the suction space 30 in the axial direction. As a result, a flow through the injection module with only a slight pressure loss is possible. Since the fuel in particular flows past the hollow tube-like pump armature 22, also waste heat of the coil 21 can be absorbed very well. As a result, the fuel heats up and rises and flows back to the tank via the fuel return line 6b. During operation of the injection device, this thus leads to a fuel circulation, which constantly dissipates heat via the fuel return line 6b. This has the additional effect that, if during heating of the fuel gas bubbles arise, this can be easily discharged through the substantially vertically aligned bore 22a in the pump armature 22 upwards.

Since the flat armature 23 is also annular, a Rückströmpfad can be placed through the center of the injection module. This results in a particularly compact design. It should also be noted that the magnetic circuit 40 may be provided as an insert and when spraying the

Housing 25 can be injected into the housing. The bushing 35 is preferably pressed by a press fit into the housing 25. As a result, the injection module can be produced particularly inexpensively and with a small number of parts.

Figures 5 and 6 show an alternative embodiment of a flat armature 23. In this case, the

Flat anchor 23 also three openings 51, 52, 53 on. However, a sealing seat is provided separately along an outer circumference of each opening 51, 52, 53. This alternative flat armature has the particular advantage that lower forces are necessary for opening, as compared to the flat armature shown in Figures 3 and 4, a reduced by the intermediate regions between the openings 51, 52, 53 area with the bypass line 12 in contact stands. It should also be noted that depending on the sealing requirements on the flat armature 23 for a better seal, for example, a plastic element or a rubber element or a sealing coating may be provided on one or both sealing partners.

Figure 7 shows an injection device according to a second embodiment of the invention, wherein identical or functionally identical parts are denoted by the same reference numerals as in the preceding embodiment.

The second embodiment corresponds essentially to the first embodiment, wherein, in contrast to the first embodiment, a different slot control is provided for the pump chamber 29 in the second embodiment. As can be seen from FIG. 7, a groove 50 formed in the axial direction X-X is provided in the piston 26. Via the groove 50, a connection between the pump chamber 29 and the suction chamber 30 is established when the piston 26 is located in an upper portion of a piston stroke. A pressure build-up in the pump chamber 29 thus begins only when the piston 26 has been moved until the groove 50 is covered by the liner 35 and the connection between the pump chamber 29 and the suction chamber 30 is interrupted. This structure is particularly easy to provide, without, for example, openings must be provided in the flange 25c and the sleeve 35. The disadvantage here is merely that the entire fuel flow must be filtered, it is no longer possible to filter only the sucked into the pump chamber 20 fuel. A fuel filter must thus be provided in the fuel supply line 6a. Otherwise, the embodiment corresponds to the previous embodiment, so that reference can be made to the description given there.

The described embodiments thus show an injection module 2, which is constructed very compact and by the annular design of the flat armature 23 and the

Pump armature 22 allows axial flow through the injection module with fuel. As a result, in particular heat-related problems can be avoided, since the circulating fuel, the resulting heat during operation can be absorbed by the fuel and can be returned to the tank. As a result, a particularly high level of operational reliability can be achieved.

Claims

claims

An injection apparatus comprising a fuel pump (20a), a pressure regulator (20b), a

Injector (20c) and an aerator (2Od), characterized in that the fuel pump (20a), the injector (20c) and the aerator (2Od) are an integral part of a compact injection module (2), the pressure regulator (20b) an integral part of Injector (20c), the fuel pump (20a) comprises a piston (26), a pump armature (22) and a pump chamber (31), the air actuator (2Od) comprises a valve seat (54, 55) and a flat armature (23) and the pump anchor (22) and the flat armature (23) by means of a common coil (21) are actuated.

2. Injection device according to claim 1, characterized in that the pump armature (22) is annular and a return path for fuel passes through the annular pump armature.

3. Injection device according to one of the preceding claims, characterized in that the flat armature (23) of the Luftstellers (2Od) is annular.

4. Injection device according to claim 3, characterized in that the return path for fuel through the annular flat armature (23).

5. Injection device according to one of the preceding claims, characterized in that the flat armature (23) by means of a return spring (28) is fixed to a housing (25).

6. Injection device according to one of the preceding claims, characterized in that a connection passage (36) between the pump chamber (29) and a suction space (30) in the axial direction (X-X) of the pump piston (26) is arranged below a top dead center of the pump piston.

7. Injection device according to claim 6, characterized in that the connection passage (36) in a lower annular channel region (30a) of the suction chamber (30) opens.

8. Injection device according to claim 7, characterized in that between the annular channel region (30a) and a main region of the suction chamber (30), a filter (37) is arranged.

9. Injection device according to one of claims 1 to 5, characterized in that the Pump piston (26) has a recess (50), in particular a longitudinal groove, which extends on the outer circumference of the pump piston (26) up to a pumping space directed pressure surface of the pump piston (26) and the recess (50) at the beginning of a pressure build-up phase of the fuel pump ( 20a) establishes a connection between the pump chamber (29) and the suction chamber (30) and after covering a predetermined stroke of the pump piston (26) the connection via the recess (50) is interrupted.

10. Injection device according to one of the preceding claims, characterized in that the pump piston (26) in a housing (25) fixed bushing (35) is arranged.

11. Injection device according to one of the preceding claims, characterized in that the pressure regulator (20b) comprises an outwardly opening valve element (33), a valve element (33) biasing spring element (34) and a Zumessdrossel (32) to the injection pressure regulate.

12. Internal combustion engine comprising exactly one or exactly two cylinders and an injection device according to one of the preceding claims.