CN1675463A - Fuel injection device for an internal combustion engine - Google Patents

Abstract

Disclosed is a fuel injection device comprising at least one high-pressure pump (14), by means of which fuel is conveyed into a reservoir (16) and which is provided with a pump piston (36) that is driven by a camshaft (30) so as to perform a stroke. Fuel is conveyed from a fuel storage container (10) to the at least one high-pressure pump by means of a conveying pump (12). Injectors (20) which are connected to the reservoir (16) inject fuel at the cylinders of the internal combustion engine. A fuel gauging device (46) that is disposed between the conveying pump (12) and the at least one high-pressure pump (14) adjusts the fuel fed from the conveying pump (12) to the at least one high-pressure pump (14) such that the at least one high-pressure pump (14) conveys a quantity of fuel into the reservoir (16), which is required in order to maintain a given pressure within the reservoir (16).

Description

Fuel injection devices for internal combustion engines

technical field

The invention relates to a fuel injection system for an internal combustion engine of the type specified in claim 1 .

DE 195 15 191 A1 already discloses a fuel injection device. This fuel injection system has a plurality of high-pressure pumps, each of which has a pump plunger driven in a stroke movement by the camshaft of the internal combustion engine, and a delivery pump via which fuel is delivered from the fuel tank To these high-pressure pumps, the fuel is delivered via the high-pressure pumps into a reservoir, to which at least one injector is connected, through which the fuel is injected into the cylinders of the internal combustion engine. In order to control the quantity of fuel delivered by the high-pressure pumps to the accumulator, a solenoid valve is arranged on each high-pressure pump, via which the connection of the high-pressure pump to a discharge region is controlled. The fuel is delivered via the high-pressure pump into the accumulator when the corresponding high-pressure pump is disconnected from the drain region by means of a solenoid valve. No fuel is delivered via the high-pressure pump into the accumulator if the corresponding high-pressure pump is connected to the outflow region via the solenoid valve. Since there is a solenoid valve for each high-pressure pump, the fuel injection system has a complex construction.

Advantages of the invention

In contrast, the advantage of the fuel injection device according to the invention with the features of claim 1 is that the fuel injection device has a simple construction because only one fuel metering device is required, by means of which the at least one The amount of fuel delivered to the reservoir by the high-pressure pump is regulated.

Advantageous refinements and developments of the fuel injection device according to the invention are specified in the subclaims. The embodiment of claim 4 ensures that the pressure between the delivery pump and the fuel metering device is limited when no or only a small fuel inflow is regulated through the fuel metering device. The embodiment of claim 5 also ensures that no fuel is delivered via the at least one high-pressure pump, which is required under certain operating conditions of the internal combustion engine, if the inflow of fuel through the fuel metering device cannot be completely prevented. The embodiment according to claim 7 makes it possible to obtain a uniform fuel delivery in the accumulator with a small number of high-pressure pumps.

Description of drawings

Embodiments of the invention are depicted in the drawings and further explained in the following description.

FIG. 1 schematically shows a fuel injection system for an internal combustion engine.

FIG. 2 shows a part of the fuel injection system in a sectional view along line II-II in FIG. 1 .

Detailed ways

A fuel injection system, for example for an internal combustion engine of a motor vehicle, is shown in FIGS. 1 and 2 . The internal combustion engine is preferably a self-igniting internal combustion engine and has one or more cylinders. The automobile has a fuel tank 10 in which fuel for driving an internal combustion engine is stored. The fuel injection system has a delivery pump 12 via which fuel is delivered from the fuel tank 10 via a connecting line 13 to the suction side of at least one high-pressure pump 14, preferably a plurality of them, for example two. The high-pressure pump 14 delivers fuel into a reservoir 16 , which can be designed in the form of a tube or in any other desired shape. Lines 18 lead from the accumulator 16 to injectors 20 arranged on cylinders of the internal combustion engine. Each of the injectors 20 is fitted with an electrical control valve 22 , via which the opening of the injector 20 is controlled so that a fuel injection is produced or prevented via the respective injector 20 . These control valves 22 are controlled by an electronic control unit 23, through which the timing and duration of fuel injection through these injectors 20 are adjusted according to some operating parameters of the internal combustion engine, such as speed, load, temperature, etc. Sure.

The high-pressure pump 14 is driven mechanically via a camshaft 30 of the internal combustion engine and is thus proportional to the rotational speed of the internal combustion engine. Each high-pressure pump 14 has a pump housing 32 in which a pump plunger 36 is guided sealingly in a cylinder bore 34 and forms a pump in the corresponding cylinder bore 34 The boundaries of Studio 38. In the connection between the pump working chamber 38 of these high-pressure pumps 14 and the reservoir 16, a discharge valve 40 in the form of a one-way valve that is opened to the reservoir 16 is arranged respectively, through which, when the pump plunger 36 is in the suction stroke A partition is created between the working chamber 38 and the storage chamber 16 . In the connection between the pump working chambers 38 of these high-pressure pumps 14 and the pressure side of the delivery pump 12, an inflow valve 42 in the form of a non-return valve that opens towards the pump working chamber 38 is respectively arranged, through which, when the pump plunger 36 is in the delivery stroke At this time, a partition is created between the pump working chamber 38 and the delivery pump 12 .

The pump plunger 36 of the high-pressure pump 14 is directly driven by the camshaft 30 of the internal combustion engine, via which the gas exchange valve of the internal combustion engine is likewise actuated. The camshaft 30 here has a number of additional cams 44 corresponding to the number of high-pressure pumps 14 , by means of which the pump plungers 36 are driven in a stroke movement. These cams 44 are preferably made of multi-lobed cams, such as three-lobed cams as shown in FIG. When the pump 14 is used, six delivery strokes of the pump plunger 36 are produced in one revolution of the camshaft 30, whereby a uniform fuel supply is also obtained in the accumulator when the number of high-pressure pumps 14 is small, and in the accumulator 16 Only weak pressure fluctuations are produced. The pump plunger 36 is supported on the cam 44 via a slide 43 , for example a roller slide, wherein the contact between the slide 43 and the cam 44 is ensured by a spring 45 . During each suction stroke of the pump plunger 36, when the pump plunger 34 moves radially inward, the pump working chamber 38 communicates with the outlet of the delivery pump 12 and is filled with fuel when the inflow valve 42 is open, wherein the pump operates Chamber 38 is disconnected from reservoir 16 by closed outlet valve 40 . During each delivery stroke of the pump plunger 36 , as it moves radially outward, the pump working chamber 38 communicates with the reservoir 16 when the outlet valve 40 is open and with the pressure side of the delivery pump 12 through the closed inlet valve 42 . disconnect.

Furthermore, the fuel injection system has a fuel metering device 46 which is arranged between the pressure side of the delivery pump 12 and the inlet side of the high-pressure pump 14 . The fuel metering device 46 is formed, for example, by an electrically controlled proportional valve, which has an actuator 47 and a valve element 48 movable by the action of the actuator, the actuator 47 being, for example, an electromagnet or piezo actuator , a variable flow cross section is adjusted via the valve element. Actuator 47 is controlled by controller 23 in such a way that a defined flow cross section is regulated via valve element 48 of fuel distribution device 46 in the connection between delivery pump 12 and high-pressure pump 14 . In this way, the flow cross section can be continuously adjusted by the valve element 48 between a maximum flow cross section and a minimum flow cross section. Preferably, the flow cross section can be at least approximately completely closed by the valve element 48 . A pressure sensor 49 is connected to the controller 23 , via which sensor 49 the pressure in the reservoir 16 is measured at least indirectly and an electrical signal of the pressure is supplied to the controller 23 . The remaining signals of the operating conditions of the internal combustion engine are supplied to the control unit 23 by other sensor devices, eg for rotational speed, load, internal combustion engine coolant temperature. A specific setpoint value for the pressure in the accumulator 16 is predetermined as a function of the operating conditions of the internal combustion engine, the signal of the actual pressure value being supplied to the control unit 23 via the pressure sensor 49 . The fuel metering device 46 is controlled by the controller 23 as a function of the deviation of the actual value from the target value in such a way that this deviation is eliminated. When the actual value of the pressure in the accumulator 16 is smaller than the desired value, the fuel metering device 46 is controlled by the controller 23 in such a way that it sets a larger flow cross section between the delivery pump 12 and the high-pressure pump 14, so that by High-pressure pump 14 delivers a larger fuel quantity to accumulator 16 . When the actual value of the pressure in the accumulator 16 is greater than the target value, the fuel metering device 46 is controlled by the controller 23 in such a way that it sets a smaller flow cross section between the delivery pump 12 and the high-pressure pump 14, so that A small fuel quantity is delivered to the accumulator 16 by the high-pressure pump 14 .

From the connecting line 13 between the delivery pump 12 and the high-pressure pump 14, a bypass connecting line 50 is branched off upstream before the fuel metering device 46, which leads to a pressure relief area, for example a port to the fuel tank 10. The return line 54 or the inlet side of the delivery pump 12 can serve as this pressure relief area. A relief valve 52 that opens to the pressure relief area is arranged in the bypass connection oil passage 50. Pressed area releases. If a complete delivery is not to take place via the high-pressure pump 14 and the fuel metering device 46 does not release the maximum flow cross-section, the pressure between the delivery pump 12 and the fuel metering device 46 therefore increases when the overflow valve 52 is opened. When the pressure is exceeded, the fuel is discharged into the pressure relief area, so that the pressure between delivery pump 12 and fuel metering device 46 is limited.

In addition, from the connecting oil passage 13 between the delivery pump 12 and the high-pressure pump 14 downstream of the fuel dosing device 46, a bypass connecting oil passage 56 is branched between the fuel dosing device 46 and the high-pressure pump 14, It leads to a pressure relief area, which in turn can be used as the return line 54 or the inlet side of the delivery pump 12 . A throttle point 58 is arranged in this further bypass connection line 56 . Under certain operating conditions of the internal combustion engine, for example thrust operation, it is not permissible for fuel to be delivered by the high-pressure pump 14 into the accumulator 16 . Fuel still passes through fuel metering device 46 if the flow cross section between delivery pump 12 and high-pressure pump 14 cannot be completely closed reliably by fuel metering device 46 . This fuel is discharged to the pressure relief area via this further bypass connection oil line 56 , so that it cannot be sucked in by the high-pressure pump 14 and conveyed into the accumulator 16 . The amount of fuel flowing to the pressure relief area is restricted via a throttle point 58 .

The high-pressure pumps 14 are functionally arranged in parallel with one another and deliver fuel independently of one another into the accumulator 16 . The high-pressure pumps 14 are inserted, for example, into bores 60 of a housing 61 , such as a crankcase or a cylinder head of an internal combustion engine. The fuel metering device 46, the bypass connection 50 with the overflow valve 52 and the bypass connection 56 with the throttle point 58 can likewise be arranged in the housing of the internal combustion engine, in particular the crankcase 61 or cylinder cover. Delivery pump 12 can have its own drive, for example an electric drive, or be driven by an internal combustion engine, for example likewise by camshaft 30 . A fuel filter 62 , which can be designed as a pre-filter, can be arranged in the connection path of delivery pump 12 to fuel tank 10 . Alternatively or additionally, a fuel filter 63 , which can be designed as a fine filter, can also be arranged on the connecting line 13 of the delivery pump 12 to the high-pressure pump 14 . In addition, a pressure regulating valve 64 can be provided, by means of which the pressure in the storage chamber 16 can be adjusted, by means of which it controls a connection to the pressure relief area, through which the fuel can be controlled from the storage 16 discharge. Instead of the pressure regulating valve, it is also possible to provide a pressure limiting valve by means of which the pressure in the reservoir 16 is limited.

Claims (7)

1. fuel injection system that is used for internal-combustion engine, have at least one high-pressure service pump (14) and have a transfer pump (12), fuel oil is transported in the storage (16) by this high-pressure service pump, high-pressure service pump has the pump plunger (36) that a camshaft by internal-combustion engine (30) drives in a stroke motion, fuel is transported to described high-pressure service pump (14) by transfer pump (12) from fuel tank (10), wherein, some spargers (20) are connected with this storage (16), be injected in the cylinder of internal-combustion engine by these spargers (20) fuel, it is characterized in that: between transfer pump (12) and described at least one high-pressure service pump (14), settled a fuel metering unit (46), regulated like this to the inflow of described at least one high-pressure service pump (14) from this transfer pump (12) by its fuel, make the fuel quantity of carrying needs by described at least one high-pressure service pump (14) to storage (16) in, so as in storage (16) predetermined pressure of maintenance.

2. fuel injection system as claimed in claim 1 is characterized in that: obtain a variable passage section by this fuel metering unit (46) adjusting in the connection oil circuit (13) between described transfer pump (12) and described at least one high-pressure service pump (14).

3. as the fuel injection system of claim 1 or 2, it is characterized in that: described fuel metering unit (46) is by an electric control device (23) control, and a sensor device (49) that is used for measuring storage (16) pressure is connected with this electric control device (23).

4. as the fuel injection system of one of claim 1 to 3, it is characterized in that: bypass of pass-out connects oil circuit (50) and leads to a pressure release zone (54) between described transfer pump (12) and described at least one high-pressure service pump (14), this pressure release zone is by a relief valve (52) control, and this relief valve (52) makes bypass connect oil circuit (50) to discharge when surpassing a predetermined pressure.

5. as the fuel injection system of one of claim 1 to 4, it is characterized in that: one of pass-out is led to the bypass connection oil circuit (56) in a pressure release zone (54) between described fuel metering unit (46) and described at least one high-pressure service pump (14), connects in oil circuit in this bypass to be provided with a throttle point (58).

6. as the fuel injection system of one of front claim, it is characterized in that: this at least one high-pressure service pump (14) and fuel metering unit (46) and in case of necessity this relief valve (52) and/or throttle point (58) be positioned on the casing, preferably on the crankcase of internal-combustion engine.

7. as the fuel injection system of one of front claim, it is characterized in that: the internal combustion (IC) engine camshaft (30) that is used to drive the pump plunger (36) of at least one high-pressure service pump (14) has salient angle cam more than (44).