WO2009071401A1

WO2009071401A1 - Compact injection device having two armatures

Info

Publication number: WO2009071401A1
Application number: PCT/EP2008/064846
Authority: WO
Inventors: Udo Sieber; Walter Maeurer; Harald Lang
Original assignee: Robert Bosch Gmbh
Priority date: 2007-12-07
Filing date: 2008-11-03
Publication date: 2009-06-11
Also published as: DE102007058955A1; CN101889139A; CN101889139B

Abstract

The present invention relates to an injection device, comprising a fuel pump (20a), a pressure controller (20b), an injector (20c), and an air actuator (20d), characterized in that the fuel pump (20a), the pressure controller (20b), the injector (20c), and the air actuator (20d) are integral parts of an injection module (2), and the injection device further comprises exactly one actuator which simultaneously activates the fuel pump (20a) and the air actuator (20d), wherein the actuator comprises a coil (21), a first armature (22), and a second armature (23), and a first working gap (S1) is provided on the first armature (22) and a second working gap (S2) is provided on the second armature (23), and wherein a stationary seal (36) is disposed between the first armature (22) and the second armature (23) in order to seal a medium controlled by the first armature from a medium controlled by the second armature.

Description

description

title

Compact injector with two anchors

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 o.a., 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 injectors are very expensive and especially 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. As a result, the injection device according to the invention in particular at

Small internal combustion engines, e.g. used in two-wheeled or lawnmowers or similar. This is inventively achieved in that the injection device comprises a fuel pump, a pressure regulator for controlling an injection pressure, an injector and an air actuator, which are integral components of an injection module. The injection module is a compact, small-sized component, in which the fuel pump, the pressure regulator, the injector and the air actuator are arranged. The injection device comprises exactly one actuator which simultaneously actuates the fuel pump and the aerator. As a result, in each case a separate actuator for the aerator or the fuel pump can be omitted in each case, so that the number of components is significantly reduced. Of course, this also results in a cost reduction. Thus, the common actuator assumes first the function of the pump drive and secondly the function of the actuator for the air actuator. The common actuator may perform a simultaneous or sequential actuation of the fuel pump and the air actuator, wherein the actuator comprises a coil, a first armature and a second armature. Here, the first armature of the fuel pump is assigned and the second armature the air actuator, and both anchors can be activated by means of the common coil. Furthermore, the injection device according to the invention comprises at the first anchor a first working gap and at the second anchor a second working gap and a stationary seal. The stationary seal is arranged at a region between the air plate and the fuel pump to provide a sealing function between the media of the air regulator (air) and the fuel pump (fuel). This has the great advantage, in particular, that a stationary seal can be used to separate the two media streams. Thus, the seal can be made very simple and inexpensive and also has an improved life and lower probability of failure. 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.

Preferably, the actuator comprises a first return element for the first armature and a second return element for the second armature, which have different spring constants, so that when energizing the coil of the first and second working gap are closed sequentially.

More preferably, the first armature is associated with the first working gap the air actuator and associated with the second armature with the second working gap of the fuel pump. In this case, the first working gap is preferably closed before the second working gap. In order to have a simple and inexpensive construction, the stationary seal is preferably an O-ring.

According to a further preferred embodiment of the present invention, the seal between the first anchor and the second anchor is arranged on a stationary housing component and seals there.

Particularly preferably, the stationary housing in the case of the component has a substantially cup-shaped form and the seal is arranged on a directed to the first armature bottom portion of the housing component. Particularly preferably, a height of the first working gap is determined by a height of the seal.

According to an alternative embodiment of the present invention, the seal is arranged on a pot-shaped, fixed housing component at its radial jacket region. Here, a groove is preferably provided in the jacket region for receiving the seal.

Preferably, the fuel pump comprises a pumping chamber and further a first, a second and a third check valve, which are arranged on supply lines or outlets of the pumping chamber. Here, the first check valve between a supply area for fuel and the pumping chamber is arranged. The second check valve is disposed between the pumping chamber and the injector, and the third check valve is disposed between the pumping chamber and a discharge area of overpressure peaks. The use of the pumping chamber allows a particularly compact and thus space-saving and cost-effective design. The pump chamber is preferably arranged on a common axis with the first and second armatures. The pumping chamber preferably has a volume which corresponds to a volume of a maximum injectable amount of fuel at maximum injection pressure. More preferably, the intake area and the return area are connected to each other and form a common larger space. As a result, in particular, pressure fluctuations due to the increased volume of space, in particular during the intake phase of the fuel pump can be avoided.

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, preferred embodiments 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 the injection device according to the first embodiment, and

Figure 3 is a schematic view of an 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 a first embodiment will be described in detail with reference to Figures 1 and 2.

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, a pressure regulator, an injector 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 of the bypass line 12 lies directly adjacent to the injector of the injection module. 2 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 provided with a cooling water sensor 15, an oil temperature sensor 16 and a sensor unit 17 for the

Detecting a throttle position, a temperature in the intake manifold 8 and a pressure in the intake manifold 8 connected. The control unit 5 controls the injection module 2 on the basis of the received signals.

The inventive injection device is thus provided as an injection module 2 with a fuel pump 20a, a pressure regulator 20b, an injector 20c and an aerator 2Od, and can be designed to be particularly compact and physically small. 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 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 multi-part housing 25 is provided. A common actuator simultaneously actuates the fuel pump 20a and the aerator 2Od. The common actuator comprises a coil 21, a first armature 22 and a second armature 23. As can be seen from FIG. 2, the first armature 22 is part of the air actuator 2Od, wherein the armature 22 is formed at one end as a valve member 22a on a valve seat 12a of a bypass line 12, the bypass line 12 can release or close. The aerator 2Od is further associated with a first return spring 28. The actuator further includes a second armature 23, which in this embodiment is a part of the fuel pump 20a. Here, the second armature 23 is the piston of the fuel pump 20a. The second armature 23 is a cylindrical member and has at a directed in the direction of the air actuator 2Od end a sleeve 23 a, which in addition to a guide function also has a support function for a second return spring 24 for resetting the second armature 23. The coil 21 actuates, when energized, both the first armature 22 and the second armature 23. After eliminating the energization of the coil 21, the first return spring 28 and the second return spring 24, the two anchors back into the in Figure 2 back home positions shown. The position shown in Figure 2 is a position at the end of a suction stroke of the fuel pump 20a. The injection module 2 further comprises a multi-part housing 25, comprising a first housing part 25a, a second housing part 25b, a third housing part 25c and a fourth housing part 25d. The fourth housing part 25d is arranged between the fuel pump 20a and the aerator 2Od. In this case, the fourth housing part 25d has a substantially cup-shaped form and additionally has a stop 26 on an inner bottom area. The stop 26 is fixedly attached to the inner bottom of the fourth housing part 25d and serves as a stop for the sleeve 23a of the second armature. Alternatively, the stop 26 can also be attached to the armature 23a. As can also be seen from FIG. 2, the first return spring 28 is arranged on an outer base surface of the fourth housing part 25d and is braced against this outer base region. As shown in Figure 2, the fourth housing part 25d is arranged stationary within the coil 21 and connected via a sleeve 34 with the second housing part 25b. In the second housing part 25b connections for the fuel supply line 6a and 6b are arranged for a fuel return line. The fuel supply line 6a opens into an intake region 32 and the fuel return line 6b starts from a return region 33 in the housing. Here, the intake area 32 and the return area 33 are connected to each other and form a großvo lumigen space 40, which in particular pressure fluctuations, which may occur, for example, in the intake phase of the fuel pump 20a, completely or at least partially compensate. It should be noted that it is also possible that the suction region 32 is provided separately from the return region 33. Further, the fuel return line 6b can not lead back into a tank, but alternatively be connected to the fuel supply line 6a.

The third housing part 25 c is also formed substantially cup-shaped and defines a pumping chamber 27, in which fuel by means of the second armature 23 can be placed under pressure. In this case, a first check valve 29, a second check valve 30 and a third check valve 31 are arranged in the third housing part 25. The three check valves have the same structure and differ only in different spring strengths of your return springs. The first check valve 29 connects the suction region 32 to the pumping chamber 27. The second check valve 30 connects the pumping chamber to a chamber in the injector 20c. The third check valve 31 connects the pumping chamber 27 with a return region 33, from which the fuel return line 6b goes off. The third check valve 31 in this case forms the pressure regulator 20b in order to reduce an overpressure possibly arising in the third pumping chamber 27. The second check valve 30 is further configured to open from a predetermined pressure in the pumping chamber 27 so that fuel can flow to the injector 20c. The injector 20c opens automatically from a predetermined pressure against a restoring force of a spring or alternatively can be opened via a control device, not shown. The injector 20c injects fuel into the intake manifold 8. The pumping chamber 27, the first armature 22 and the second armature 23 lie on a common axis XX. As can further be seen from FIG. 2, the first armature 22 is assigned a first working gap S1 and the second armature 23 is assigned a second working gap S2. The first working gap Sl is defined by a washer 35. The washer 35 is disposed between a housing of the air actuator 2Od and the housing member 25d. At the radial inside of the

Washer 35 is further provided a seal 36 in the form of an O-ring. The seal 36 seals the air actuator 2Od from the other regions of the injection module, which come into contact with the fuel. The seal 36 is arranged stationary, so that it is not subject to dynamic loads. Also, the seal 36 is provided such that it does not need to experience large pressure differences between the air in the aerator 2Od and the fuel, since the pumping chamber 27 of the fuel pump 20a is located in the cup-shaped housing member 25c. Thus, the seal 36 can be constructed very easily and inexpensively. It should be noted that the seal 36 may alternatively be disposed on the radially outer side of the washer 35.

The function of the injection module 2 according to the invention is as follows. An intake phase of the fuel pump 20a is introduced through the second return element 24, wherein the rest position of the second return element 24 defines the end of the intake phase. During the suction phase, the first check valve 29 is opened and the second and third check valves 30, 31 are each closed. This allows fuel through the open first check valve 29 in the

Pumping chamber 27 flow. The coil 21 is then energized so that the second armature 23 is moved in the direction of the arrow A in order to pressurize the fluid in the pumping chamber 27. This closes the first check valve 29, and as long as there is still a low pressure level in the pumping chamber 27, the second and the third check valve 30, 31 also remain closed. This condition is shown in FIG. By the energization of the coil 21 and the first armature 22 is attracted and moved in the direction of arrow B, so that the air actuator opens 2Od. From a predetermined pressure level in the pump chamber 27 then opens the second check valve 30 so that fluid under pressure to the injector 20c can flow and can be injected from there if necessary. Should a pressure in the pumping chamber 27 become too great, ie greater than a reference value, the third check valve 31 opens in order to reduce such pressure peaks. Thus, the third check valve 31 takes over the function of the pressure regulator 20b. Simultaneously with the actuation of the fuel pump 20a, therefore, when the coil 21 is energized, the first armature 22 of the air regulator 2Od is also attracted in the direction of the arrow B. As a result, the air actuator opens 2Od, so that air can flow through the bypass line 12. When the restoring force of the first return member 28 is set smaller than that of the second return member 24, the air actuator 2Od opens before the fuel pump enters the pressure phase. As can be seen from FIG. 2, a possible stroke of the first armature 22 and of the second armature 23 is limited. The first armature 22 can perform a maximum lift, corresponding to the first working gap S 1, until the first armature 22 abuts the outwardly directed base surface of the fourth housing part 25d. The height of the gap Sl is determined by the thickness of the

Washer 35 is determined. At the second armature 22, the second working gap S2 is provided, which is greater than the working gap Sl of the first armature 22. Thus, each anchor is assigned its own working gap. In this case, each of these working column is a part of the magnetic circuit of the coil 21. Now, despite this magnetic coupling of the armature 22, 23 no or only a very small loss of time during a force build-up in the second working gap S2 (and possibly in the third, fourth, etc. working gap) have, the first return spring 28 is designed such that in operating conditions of the small motor 1, in which no delay in the power buildup may occur in the second working gap S2, this delay is minimized or completely prevented. Such an operating state is, for example, a load operation of the small engine 1. In contrast to this operating state, it is desired in an idle operating state that the air actuator 2Od is not constantly open. Thus, the restoring force of the first return element 28 is to be selected such that the restoring force at low speeds is sufficient to close the air actuator 2Od between individual activations of the coil 21 in the idle mode of the small motor. At high speeds, in contrast to the idle state, a faster activation of the coil 21 occurs. As a result, the time for the first return element 28 is no longer sufficient to fully close the air actuator 2Od again. As a result, the aerator 2Od almost always fully open at high speeds. For the operation of the small motor 1, this state is without any disadvantage or an advantage, since over the open bypass 12 additional air can be performed just before the inlet valve 10.

Thus, at high speeds, a delay in the buildup of force at the second working gap S2 is significantly lower, since the first working gap Sl does not first have to be completely closed.

Thus, according to the invention, the injection module 2 has a common actuator for the fuel pump 20a and the aerator 2Od. As a result, only one coil and a single electric power amplifier with wiring in the fuel pump 20a and the aerator 2Od is necessary. Furthermore, in the operating states of the small engine 1 in which it is required, ie usually idle, the aerator 2Od can open and close and in operating states in which it is not absolutely required, it can be ensured that despite the common actuator with the Fuel pump 20 a actuation of the fuel pump 20 a is not delayed or otherwise hindered. Furthermore, a simple static seal for sealing the two media streams can be provided from each other, wherein the seal on the housing component of the Injector is arranged that it has no or only a very small pressure gradient between the two media has to seal.

In the following, an injection device 1 according to a second exemplary embodiment of the invention will be described in detail with reference to FIG. Identical or functionally identical parts are denoted by the same reference numerals as in the first exemplary embodiment.

The second embodiment substantially corresponds to the first embodiment, wherein, in contrast to the first embodiment in the second embodiment, the seal 36 is disposed on a radially outer circumferential surface of the housing member 25d. Here is in the

Housing member 25d provided an annular groove 37, in which the formed as an O-ring seal 36 is arranged. Thus, the seal 36 can be securely held in the stationary housing member 25d.

Furthermore, the injection module according to the second embodiment comprises a second sealing ring 38, which seals the suction region 32 and the return region 33 from the environment. The second sealing ring is arranged in the third housing part 25c in a correspondingly formed groove.

Further, unlike the first embodiment in the second embodiment, the third, substantially cup-shaped, housing member 25c is formed slightly longer in the axial direction X-X. This defines a space 41 in which the second working gap S2 between the second armature 23 and the third housing component 25c is defined. The space 41 is connected via a branch line 46 with the return area 33. As can further be seen from FIG. 3, the second armature 23 is formed from a cup-shaped base part 23 a and a rod 23 b. At the end of the rod 23b, a disc element 23c is provided, via which the second armature 23 is connected to the piston 42. In the piston 42, a central recess 43 is formed, in which the disc element 23c of the second armature is arranged. The disc element 23c is held by an undercut 44 on the piston. Further, two return springs 24 and 45 are provided. The return spring 24 thereby returns the armature 23 in its initial position, wherein the return spring 24 between a paragraph in the third

Housing component 25 c and the pot 23 a of the armature 23 is arranged. The third return spring 45 is disposed between the armature 23, more precisely the pot 23 a and the armature-facing end of the piston 42. As can be seen from FIG. 3, the two return springs 24, 45 are arranged parallel to one another in the space 41. The selected construction of the armature 23 with a separate piston 44 makes it possible that, after an obstruction of the coil 21, first the armature 23 is moved downwards, and the piston 42 still remains in its position. Only when the disc member 23 c of the armature 23 presses against the inner bottom surface of the piston 42, the piston 42 moved together with the armature 23, so that the fluid located in the pump chamber 27 is pressurized. Thus, a delayed response of the piston pump 20a can be realized. The provision of the piston 42 is then also delayed, since the second return spring 24 first resets the armature 23, which then takes over the undercut 44 on the piston 42 the piston. It should be noted that the third return spring 45 can also be designed so that it provides a relatively high rigidity and thus a high spring force, so that shortly after actuation of the second armature 23, the piston 42 can be moved via the third return spring 45.

Otherwise, this embodiment corresponds to the previous embodiment, so that reference can be made to the description given there.

For all embodiments, it should be noted that the injection device is constructed very compact and inexpensive and the injection module 2 each comprise as integral components a fuel pump 20a, a pressure regulator 20b, an injector 20c and an aerator 2Od. Here, in particular, a common actuator for the aerator 2Od and the fuel pump 20a with two anchors 22, 23 is provided. In the embodiments, in each case a magnetic actuator by energizing a coil has been described as an actuator. It should be noted, however, that in principle other possible actuators may be used, e.g. a piezoactuator. It should also be noted that the described closure element 22a of the air actuator 2Od can also be designed as a tapering, in particular conical, end region of the armature 22, or in any other way, for example as a sphere or part sphere.

Claims

claims

An injection apparatus comprising a fuel pump (20a), a pressure regulator (20b), an injector (20c) and an aerator (20d), characterized in that the fuel pump (20a), the pressure regulator (20b), the injector (20c) and the air actuator (2Od) are an integral part of an injection module (2), and the injector further comprises precisely one actuator which simultaneously actuates the fuel pump (20a) and the air actuator (2Od), the actuator comprising a coil (21), a first one Anchor (22) and a second armature (23), and at the first armature (22) a first working gap (Sl) and the second armature (23) a second working gap (S2) is provided, and wherein between the first armature (22 ) and the second armature (23) a stationary seal (36) is arranged to seal a medium controlled by the first anchor from a medium controlled by the second anchor.

2. Injection device according to claim 1, characterized in that the actuator comprises a first return element (28) for the first armature (22) and a second return element (24) for the second armature (23), wherein the first and second return element different spring constants have such that when energizing the coil (21) of the first and second working gap (Sl, S2) are closed sequentially.

3. Injection device according to claim 2, characterized in that the first armature (22) with the first working gap (Sl) is associated with the air actuator (2Od) and the second armature (23) with the second working gap (S2) of the fuel pump (20a) is assigned, and the first working gap (Sl) before the second working gap (S2) is closed.

4. Injection device according to one of the preceding claims, characterized in that the seal (36) is an O-ring with a circular or rectangular cross-section.

5. Injection device according to one of the preceding claims, characterized in that between the first armature (22) and the second armature (23) a stationary housing member (25d) is arranged and the seal (36) on the housing member (25d) seals.

6. Injection device according to claim 5, characterized in that the housing component (25d) has a substantially cup-shaped shape and the seal (36) on a first armature (22) directed bottom portion of the housing member (25d) is arranged.

7. Injection device according to claim 5, characterized in that the housing component (25d) has a substantially cup-shaped form and the seal (36) on a radial jacket portion of the housing component (25d), in particular in an annular groove (37) is arranged.

8. Injection device according to one of the preceding claims, characterized in that the fuel pump (20a) comprises a pumping chamber (27), and the fuel pump (20a) further comprises a first check valve (29), a second check valve (30) and a third check valve (20). 31), wherein the first check valve (29) is disposed between a suction region (32) and the pumping chamber (27), the second check valve (30) is disposed between the pumping chamber (27) and the injector (20c), and the third one Check valve (31) between the pumping chamber (27) and a return region (33) is arranged.

9. Injection device according to claim 8, characterized in that the intake region (32) and the return region (33) form a common space (40) and the pumping chamber (27) in particular has a volume which corresponds to a maximum injectable amount of fuel at a maximum injection pressure ,

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

11. Internal combustion engine according to claim 10, further comprising a fuel tank (6), which is arranged above the injection module (2).