DE102008007348A1 - Injection device i.e. injection module, for use in internal combustion engine i.e. fractional horsepower engine, in e.g. two-wheeler, has pumping area with gas-filled area which is continuously present and transfers damping function - Google Patents

Abstract

The device i.e. injection module (2), has a fuel pump, a pressure controller, an injector and an air actuator, where the fuel pump, the injector and the air actuator are an integral component of the module and the controller is an integral component of the injector. The fuel pump has a piston and a pumping area, where the pumping area includes a volume with a gas-filled area and a fuel area with liquid fuel, where the gas-filled area is continuously present and transfers a damping function. The piston has a recess i.e. cylindrical hole, which receives the gas-filled area.

Description

State of the art

The 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 from the prior art in different embodiments. Especially for cost and space reasons require small combustion engines, which only one or two cylinders and a small displacement have independent solutions. applications Such small internal combustion engines are for example two-wheeled vehicles or tricycles or lawnmowers etc. Known injectors commonly include in a tank a fuel pump with a pressure regulator, where the fuel pump with a predetermined pressure in a line, z. B. a rail o. Ä., Promotes. At the End of the line, an injector is arranged, which, controlled by a control device, fuel in a suction pipe or directly injected into a combustion chamber. Such injectors However, they are very expensive and especially expensive, so they are small combustion engines also very expensive.

From the EP 1 340 906 B1 For example, an electronic control fuel injection device is known in which an injector is disposed near 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 Inventive injection device with the Features of claim 1, in contrast, the Advantage on that it has a very compact structure. Further can the injection device according to the invention be made particularly simple and inexpensive.

According to the invention the injector a fuel pump, a pressure regulator for controlling an injection pressure, an injector and an aerator, which are integral components of an injection module. The injection module is a compact, small-sized component. The pressure regulator is included integral part of the injector. The fuel pump includes a piston and a pumping space, wherein the pumping space is a volume comprising a gas-filled area and a fuel area includes. In the fuel sector is liquid fuel available. The gas-filled area remains continuous present during the operation of the injector and provides a damping function. In other words According to the invention in the pump room constantly Gas cushion included, which in addition to the damping function also a reduction of a dispersion of the injection quantity, a reduced Operating noise as well as a reduced component load ensures. Due to the presence of a permanent gas cushion becomes a speed of pressure build-up in the pump room independent from the formation of additional steam or gas bubbles constant. Here it is for the operation of the fuel pump harmless if additional gas volumes through the operation, for example by suction of gas bubbles o. Ä., contained in the pump room. The injection module can be complete be pre-assembled, so that it only connected to the necessary connections and can be installed directly into a vehicle. The Components of the injection module are preferably in a common Housing of the injection module arranged. In addition to the compactness of the injection module is another big advantage that Other components for the injection module can be minimized can.

The Subclaims show preferred developments of the invention.

Especially Preferably, the piston of the fuel pump has a recess, in which the permanent gas cushion is arranged. Further the piston is arranged in a substantially vertical direction. Here, according to the invention, a substantially vertical direction is an orientation of the longitudinal axis of the Piston at an angle of ± 10 ° from a vertical Axis understood.

Around a particularly simple and inexpensive manufacturability To provide the recess in the piston, the recess is preferably a cylindrical bore.

Further Preferably, the recess is symmetrical to a longitudinal axis formed of the injection module. This allows in particular a uniform pressure build-up during a pressure phase of the fuel pump in the pump room.

In order to provide the largest possible continuous gas cushion in the recess, the recess is preferably completely filled with gas. This also has the advantage that there is always a constant minimum volume of gas in the pump chamber volume. This can be reproducible Pump strokes are achieved.

According to one further preferred embodiment of the present invention the injection module further comprises a suction space, which is an integral part of the injection module is. A volume of the suction space is preferably greater than a volume of the pumping space. By the larger volumes of the suction space can in particular Saugpulsationen better damped during operation become. Further preferred is an opening of a connecting line between the suction chamber and the pump chamber in the axial direction of the injection module arranged closer to the injector than a mouth a connecting line between the pumping space and a return space, from which fuel is led back to the tank becomes. By this arrangement, it is possible that during a pressure stroke of the piston of the fuel pump a possibly existing additional gas volume via the connecting line between the pump room and the return room in be pushed out the return space. A pressure build-up in the pump room begins only when a control edge of the piston the mouth of the connecting pipe between the pump room and has run over the return space and the mouth is covered by the piston.

The Injector preferably comprises exactly one actuator, which simultaneously actuates the fuel pump and the aerator. In particular, in each case a separate actuator for the Air actuator or the fuel pump omitted, so that the number of components is significantly reduced. This of course results also a cost reduction. Thus, the common actuator takes over first, the function of the pump drive and second, the function the actuator for the air actuator. The common actuator can be a simultaneous actuation of the fuel pump and the air actuator, wherein the actuator is a coil, a first anchor and a second anchor. Here is the first anchor is assigned to the air plate and the second anchor the fuel pump, and both anchors can by means of common coil can be activated.

Preferably For example, the pressure regulator integrated into the injector includes an outward opening Valve element and a spring member biasing the valve element, to regulate the injection pressure. In other words, the injector is provided as an outwardly opening injector, which opens upon application of a predetermined pressure, wherein the spring force of the spring element is overcome. An injection is terminated as soon as an adjoining the injector Pressure again drops below the operating pressure, so that the outwardly opening valve element through the Spring element returned to its original position becomes.

Around To provide as compact a structure as possible is preferable the first anchor is a part of the aerator and the second anchor is a part of the fuel pump. In particular, the first armature is a valve member of the aerator and the second anchor is a piston of the fuel pump.

Further The present invention relates to an internal combustion engine, which exactly one cylinder or exactly two cylinders and an inventive Fuel injection device comprises. Particularly preferred the internal combustion engine a fuel tank, which above the Injection module is arranged. As a result, in particular, the fuel pump be designed very small.

drawing

following is a preferred embodiment of the invention described in detail with reference to the accompanying drawings. In the drawing is:

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

2 a schematic view of the injection device according to the embodiment.

Preferred embodiment the invention

The following is with reference to the 1 and 2 a small engine 1 with an injection device according to an embodiment of the invention described in detail.

1 schematically shows the structure of the small motor 1 , which is designed as a single-cylinder engine. The small engine 1 includes a cylinder 3 , a reciprocating piston 4 , a control unit 5 and a tank 6 , The Tank 6 is via a fuel supply line 6a with an injection module 2 connected. A fuel return line 6b goes from the injection module 2 back to the tank 6 , How out 1 schematically is the tank 6 above the injection module 2 arranged. 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 very compact.

The small engine 1 further includes a throttle valve 7 which is in a suction tube 8th is arranged. At the cylinder 3 are also a spark plug 9 , an inlet valve 10 and an exhaust valve 11 arranged. The reference number 12 refers to a bypass line for air, which air from the intake manifold 8th from an area in the flow direction of the air in front of the throttle valve 7 branches off and directly to the injection module 2 integrated air actuator leads. An outlet 12z the bypass line 12 opens in the intake manifold 8th behind the throttle 7 ,

The small engine 1 further includes an exhaust pipe 13 passing through the outlet valve 11 is released or closed. Further, an oxygen sensor 14 at the exhaust pipe 13 provided, which with the control unit 5 connected, and the control unit 5 is also with 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 8th and a pressure in the intake manifold 8th connected. The control unit 5 controls the injection module based on the received signals 2 ,

The injection device according to the invention is thus an injection module 2 provided with a fuel pump, a pressure regulator, an injector and an air actuator, 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 in the small engine 1 must be installed 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 according to the invention 2 For example, be used in small engines of two-wheelers or lawn mowers.

2 shows the injection module 2 in detail. In the injection module 2 are the fuel pump 20a , the pressure regulator 20b , the injector 20c and the air actuator 20d integrated. For this purpose, a multi-part housing 25 (in 2 shown only schematically). The pressure regulator 20b is part of the injector 20c , A common actuator simultaneously actuates the fuel pump 20a and the air plate 20d , The common actuator comprises a coil 21 , a first anchor 22 and a second anchor 23 , How out 2 is apparent, is the first anchor 22 Part of the air regulator 20d , where the anchor 22 at one end a valve member 22a has formed, which at a valve seat 12a the bypass line 12 the bypass line 12 can release or close. The air actuator 20d is also a first return spring 28 assigned. The actuator further includes a second armature 23 , which in this embodiment is a part of the fuel pump 20a is. Here is the second anchor 23 firmly with a piston 26 the fuel pump 20a connected. Alternatively, the second anchor 23 and the piston 26 be provided as separate components. The second anchor 23 is a cylindrical component and is inside the coil 21 by means of a guide element 19 guided. The guide element 19 In addition to a guide function also has a support function for the first return spring 28 on. The reference number 29 denotes a non-magnetic element around the iron circle of the coil 21 to interrupt. The sink 21 When energized, it activates both the first anchor 22 as well as the second anchor 23 , After elimination of the current supply to the coil 21 put the first return spring 28 or a second return spring 24 for the second anchor the two anchors return to the in 2 back home positions shown. The second return spring is supported on a housing block 25a and an end face of the second anchor 23 from.

How out 2 it can be seen, are on the housing 25 the fuel supply line 6a and the fuel return line 6b arranged. The fuel supply line 6a leads into a suction chamber 30 , The fuel return line 6b goes from a return room 32 out. The volume of the suction space 30 and the return room 32 are about the same. Alternatively, the suction space and the return space may also be formed as a common, annular space. In the housing block 25a is also a pump room 31 educated. The pump room 31 is about holes 51 . 52 . 53 with the intake manifold 30 , the return room 32 or the injector 20c , more precisely a pressure chamber 42 of the injector 20c , connected. Here is between the suction 30 and the pump room 32 a first check valve 33 arranged between the pump room 31 and the pressure room 42 a second check valve 34 , and between the pump room 31 and the return room 32 a third check valve 35 arranged. The pump room 31 is part of the fuel pump 20b , How out 2 it can be seen, is the piston 26 the fuel pump in the housing block 25a arranged that he is one in the pump room 31 can pressurize fluid located. In the 2 shown position is a position at the end of a suction stroke of the fuel pump 20a , The pump room 31 , the first anchor 22 and the second anchor 23 lie on a common axis XX.

How farther 2 it can be seen is on the pump room 31 directed end of the piston 26 a recess 26b educated. The recess 26b is a bore which is centered to the center axis XX of the injection module 2 in the front of the piston 26 is bored. It should be noted that the injection module 2 is substantially perpendicular, ie, is arranged at an angle ± 10 ° about a vertical. In this embodiment, the injection module is without deviation with the means axis XX arranged on the vertical. The hole 26b in the piston 26 serves to accommodate a gas cushion. Thus, a volume of the pumping room comprises 31 a gas-filled area in the recess 26b and a substantially filled with liquid (fuel) area in the actual pump chamber 31 , It should be noted that in the pump room 31 In addition, even steam bubbles o. Ä. May be present.

As in 2 shown is an estuary 51a the bore 51 between the suction chamber 30 and the pump room 31 in the axial direction XX closer to the injector 20c arranged as a muzzle 53a the bore 53 between the pump room 31 and the return room 32 , This makes it possible that at the beginning of a pressure phase possibly in the pump room 31 existing additional gas bubbles from the pump room 31 in the return room 32 be promoted because during this Teilhubs the check valve 35 is open. The end of the piston 26 forms a control edge 26a , which in the further course of the movement of the piston 26 the connection for the third check valve 35 closes, so that then the actual pressure build-up phase for the pump room 31 fuel begins. The second check valve 34 is further designed such that it starts from a predetermined pressure in the pump chamber 31 opens, leaving fuel in a pressure chamber 42 of the injector 20c can flow. The injector 20c , which integrally also the pressure regulator 20b includes for controlling the injection pressure, then opens from a predetermined pressure in the pressure chamber 42 against the force of a spring element 41 , wherein a valve element 40 is an outwardly opening valve element. The injector 20c injects fuel into the intake manifold 8th one.

Because the gas cushion in the recess 26b in the direction of movement of the piston behind the control edge 26a is, it is ensured that in the entire pump volume at least this volume of gas in the recess 26b constantly present in every operating phase. By the gas volume in the recess 26b results in a softer pressure curve during the pressure buildup phase of the fuel pump. Furthermore, this results in a reduced component load and a reduced noise. The fixed gas volume in the recess 26b Further, it ensures a reduction in the dispersion of the injection amount of the injected fuel into the suction pipe.

Should, after the control edge 26a of the piston 26 the estuary 53a the bore 53 has run over, still residual gas or gas bubbles in the pump room 31 be present, their influence on an elasticity in the pump chamber is significantly lower than it would be without the ever-existing gas cushion, resulting in a reduction in the dispersion of the injection quantity. As the gas volume, which is at least in the recess 26b is present, influence on an absolute opening pressure of the check valve 34 between the pump room 31 and the pressure room 42 has, is a restoring force of the check valve 34 adjusted accordingly. Overall, the gas cushion is in the recess 26b However, be sure that regardless of the formation of vapor or gas bubbles in the pump room 31 a speed of pressure buildup in the pump room 31 becomes more constant. This also leads to a more precise injection quantity.

The function of the injection module according to the invention 2 is as follows. A suction phase of the fuel pump 20a is through the second return element 24 initiated, wherein the rest position of the second return element 24 defines the end of the intake phase. During the intake phase is the first check valve 33 opened and the second and third check valve 34 . 35 are each closed. This allows fuel through the open first check valve 33 in the pump room 31 stream. Subsequently, a current is applied to the coil 21 so that the second anchor 23 is moved in the direction of arrow A to that in the pump room 31 pressurizing fluid under pressure. This closes the first check valve 33 and as long as still a low pressure level in the pump room 31 prevails, the second check valve remains 34 also closed. At the beginning of the pressure phase is the third check valve 35 open to possibly in the pump room 31 existing gases in the return space 32 eject. Once the control edge 26a of the piston 26 the estuary 53a the bore 53 has completely closed, begins a pressure build-up in the pump room 31 , which through the existing gas cushion in the recess 26b softer. From a predetermined pressure level then opens the second check valve 34 so that the pressurized fluid enters the pressure chamber 42 of the injector 20c can flow and is injected from there from a certain pressure level independently. With the actuation of the fuel pump 20a is when energizing the coil 21 also the first anchor 22 of the aeronaut 20d tightened in the direction of arrow B. This opens the air actuator 20d , allowing air through the bypass line 12 can flow. This allows air over the outlet 12z to the intake manifold 8th stream.

After injection, the energization of the coil 21 finished, leaving the return springs 24 and 28 the first and second anchor 22 . 23 put back in their starting positions. This will be the air actuator 20d closed again and during the return of the second anchor 23 becomes the piston 26 With withdrawn, so that the suction phase begins again. It should be noted that the restoring forces of the return springs 24 and 28 are designed so that in a clotting only energizing the coil 21 the air actuator 20d can also be operated separately, without the fuel pump 20a to press.

By always present in each operating state gas volume in the recess 26b Thus, a constant injection quantity can be ensured. Furthermore, the softer pressure build-up in the pump chamber 31 It also reduces stress on components and reduces noise. This will quiet the entire behavior of the injection module during operation. Since it is always ensured that before the start of the actual pressure buildup, a large part of possibly in the pump room 31 existing gas via the third check valve 35 can be pushed out, a further stabilization of a flow rate of the fuel pump can be achieved.

Furthermore, the injection module 2 a common actuator for the fuel pump 20a and the air plate 20d on. This is merely a coil and a single electric power amplifier with wiring in the fuel pump 20a and the air plate 20d necessary. Next, the air actuator 20d in the operating states of the small motor 1 , in which it is needed, ie, usually at idle, open and close and in operating conditions in which it is not absolutely necessary, it can be ensured that despite the common actuator with the fuel pump 20a an actuation of the fuel pump 20a not delayed or otherwise obstructed. In the embodiment, a magnetic actuator by energizing a coil has been described as an actuator. It should be noted, however, that in principle also other actuators can be used, for. B. a piezoelectric actuator. It should also be noted that the closure element described 22a of the aeronaut 20d also as a tapered, in particular conical, end portion of the anchor 22 may be executed, or in any other way, for example as a ball or part ball.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 1340906 B1 [0003]

Claims (10)

Injection device comprising a fuel pump ( 20a ), a pressure regulator ( 20b ), an injector ( 20c ) and an air plate ( 20d ), characterized in that the fuel pump ( 20a ), the injector ( 20c ) and the air actuator ( 20d ) integral part of an injection module ( 2 ), the pressure regulator ( 20b ) integral part of the injector ( 20c ), and the fuel pump ( 20a ) a piston ( 26 ) and a pump room ( 31 ), wherein the pumping space comprises a volume with a gas-filled area and a fuel area with liquid fuel, wherein the gas-filled area is continuously present and assumes a damping function. Injection device according to claim 1, characterized in that the piston ( 26 ) a recess ( 26b ), which accommodates the gas-filled region of the volume of the pump chamber and the piston ( 26 ) is arranged in a substantially vertical direction. Injection device according to claim 2, characterized in that the recess ( 26b ) is a cylindrical bore. Injection device according to claim 2 or 3, characterized in that the recess ( 26b ) in the piston symmetrically to a longitudinal axis (XX) of the injection module ( 2 ). Injection device according to one of claims 2 to 4, characterized in that the recess ( 26b ) of the piston ( 26 ) is completely filled with gas. Injection device according to one of the preceding claims, characterized in that the injection module ( 2 ) further comprises a suction space ( 30 ), which is an integral part of the injection module, wherein a volume of the suction space ( 30 ) greater than a volume of the pump space ( 31 ). Injection device according to claim 6, characterized in that an orifice ( 51a ) a connection line ( 50 ) between the suction space ( 30 ) and the pump room ( 31 ) in the axial direction (XX) of the injection module ( 2 ) closer to the injector ( 20c ) is arranged as an orifice ( 53a ) a connection line ( 53 ) between the pump room ( 31 ) and a return space ( 32 ). Injection device according to one of the preceding claims, characterized in that the injection device comprises exactly one actuator, which both the fuel pump ( 20a ) as well as the air plate ( 20d ), wherein the actuator is a coil ( 21 ), a first anchor ( 22 ) and a second anchor ( 23 ). Injection device according to one of the preceding claims, characterized in that the pressure regulator ( 20b ) an outwardly opening valve element ( 40 ) and a valve element ( 40 ) biasing spring element ( 41 ) to control the injection pressure. Internal combustion engine comprising exactly one or exactly two cylinders and an injection device according to one of the preceding Claims.