EP1252437A2

EP1252437A2 - Injection device and method for injecting a fluid

Info

Publication number: EP1252437A2
Application number: EP01909455A
Authority: EP
Inventors: Wolfgang Braun; Bernd Mahr; Martin Kropp; Hans-Christoph Magel
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2000-01-20
Filing date: 2001-01-12
Publication date: 2002-10-30
Anticipated expiration: 2021-01-12
Also published as: JP2003520317A; WO2001052916A2; ATE277279T1; WO2001052916A3; US20030127539A1; EP1252437B1; DE50103747D1; DE10002273A1; KR20020074481A; TW558607B

Abstract

The invention relates to an injection device, with an injection nozzle (42), a pressure amplifier (12), for amplifying a primary pressure, a first valve arrangement (32), for operating the pressure amplifier (12) and an actuator for operating the first valve arrangement (32), whereby the pressure amplifier (12) is activated in a first state of the first valve arrangement (32), the pressure amplifier (12) is deactivated in a second state of the first valve arrangement (32) and a flow limiter to the injection nozzle (42) is provided. The invention further relates to a method for favourable application of the above device.

Description

Injection device and method for injecting fluid

State of the art

The invention relates to an injection device with an injection nozzle, a pressure booster for increasing a primary pressure, a first valve device for controlling the pressure booster and an actuating element for actuating the first valve device. The invention further relates to a method for injecting fluid, in which a low-pressure injection takes place in a first phase and a high-pressure injection takes place in a second phase.

A generic device and a generic method are known. A basic requirement for such a system is to carry out the fuel injection with the greatest possible injection pressure. A high injection pressure has positive effects on the function of an engine; for example, pollutant emissions and fuel consumption are reduced. However, it may also be desirable to use the same system to perform lower pressure injection. Such a low-pressure injection can be used, for example, for a pre-injection which, among other things, pollution serves. By providing different pressures during an injection cycle, for example, an advantageous “boot” shape of the injection pressure curve can be achieved.

To achieve the high injection pressure, a pressure booster is provided which, by means of a hydraulic transmission, converts a primary pressure, such as that made available by a pressure accumulator, into the desired high injection pressure. A suitable increase in pressure can be set in this way through the suitable choice of the areas to which force is applied and the counterforces of elastic means.

Generic pressure intensification is particularly useful in connection with a common rail system. With the common rail accumulator injection, the primary pressure generation and the injection are decoupled. The injection pressure is generated by a high-pressure pump and made available for injection in the "rail" (fuel accumulator). In this way, it is possible in principle to implement an advantageous injection profile, since in particular the injection pressure and the injection quantity can be determined independently of one another for each operating point of the engine. However, the pressure in the common rail is currently still limited to approximately 1600 bar, so that an increase in pressure is desirable for emission reasons. A pressure booster in combination with a common rail system was able to deliver particularly good results. However, in the case of pressure-reinforced common rail systems, additional valve devices must be provided for the refilling of the various functional spaces of the pressure amplifier. According to the prior art, the entire high-pressure space in the injector and in Pressure intensifier relaxes, which leads to high relaxation losses.

FIG. 5 shows a common rail system in which an injector or an injection nozzle 110 is coupled to a pressure booster 112. The pressure booster 112 is controlled via a 2/2 valve 114, which controls the pressure in the space 134, so that, compared to the control with a 3/2 valve in the pressure booster inlet, there are comparatively low relaxation losses. The hydraulic circuit shown has a bypass path 116 in order to enable injection with rail pressure or injection with increased pressure. The activation or deactivation of the pressure booster 112 takes place by opening or closing the valve 114. However, in this system it should be noted that rail pressure is always conducted to the injector 110 via the bypass path 116. A jamming of the injector needle or the injector valve would consequently produce a continuous injection, which can ultimately lead to the destruction of the engine. It is therefore desirable to provide a system with intrinsic safety that has a design-determined maximum injection quantity, that is, an injection quantity that cannot be exceeded in the event of a system component being damaged.

For the sake of completeness, the other components of the system shown in FIG. 5 are also described. A valve 118 is connected to a control chamber 122 of the injector 110 for stroke control via an outlet throttle 120. The

Control chamber 122 is also connected to the fluid inflow via an inlet throttle 124. The fluid is also fed to the pressure chamber 126 of the injection nozzle 110. A check valve 128 is located in the fluid supply line 116, which only permits fluid transport in the direction of the injector 126. The pressure booster 112 has a low-pressure chamber 130, a high-pressure chamber 132 and a differential chamber 134. The differential chamber 134 is connected to the pressure accumulator ("rail") 138 via a throttle 136, while the low-pressure chamber 130 and the high-pressure chamber 132 are connected directly or via the check valve 128 communicate with the accumulator 138. In a four-cylinder engine, the pressure accumulator 138 has connections to four injectors, to which it makes the rail pressure available. A supply line to the pressure accumulator 138, in which a pressure sensor and a control circuit is provided, comes from a fuel tank 140 via a quantity-controlled high-pressure pump 142.

Advantages of the invention

According to claim 1, the invention builds on the prior art in that the pressure booster is activated in a first state of the first valve device, in that the pressure booster is deactivated in a second state of the first valve device and that a flow rate limitation to the injection nozzle is provided. On the one hand, the invention enables a pressure booster to be controlled by a valve in a simple manner, with only slight relaxation losses, and this is advantageously combined with a flow rate limitation to the injection nozzle. Thus, it is excluded that jamming of the nozzle needle or the control valve of the injection nozzle could lead to continuous injection and ultimately to the destruction of the engine.

The pressure booster preferably has a low-pressure space, a high-pressure space and a differential space, wherein the first valve device is connected to the differential space with a first connection, the first valve device is connected to a return connection system with a second connection, and the first valve device is open in the first state, so that the differential space is connected to the return system. When the valve is closed, the piston of the pressure booster is therefore pressure-balanced, since the rail pressure is established in the differential space. There is no pressure increase. However, if the valve is opened, this measure relieves the differential space. As a result, the pressure intensifier is activated and an injection with increased pressure can take place.

It is advantageous if the low pressure chamber of the pressure booster is connected to the differential chamber of the pressure booster via a first throttle and a second valve device, the first throttle and the second valve device being arranged in parallel, the second valve device the flow of a fluid from the differential room releases to the low pressure space and the second valve device blocks the flow of a fluid from the low pressure space to the differential space. The second valve device thus enables the differential space to be depressurized when the first valve device is open, so that the pressure booster can be activated. The second valve unit prevents an overpressure from building up in the differential space compared to the low-pressure space. The differential space is filled via the throttle when the pressure booster is reset.

The second valve device is preferably a non-return valve. This is suitable for performing the functions of the second valve device described. The low-pressure chamber of the pressure booster is preferably connected to the high-pressure chamber of the pressure booster via a second throttle and a non-return valve, wherein the non-return valve enables the flow of a fluid from the low-pressure chamber to the high-pressure chamber and the non-return valve blocks the flow of a fluid from the high-pressure chamber to the low-pressure chamber. The check valve is useful so that the pressure from the high pressure chamber does not decrease in the direction of the low pressure chamber. The throttle ensures that the connection has a sufficiently small flow cross section so that it cannot serve as a bypass for an injection. This measure creates a pressure difference between the low-pressure chamber and the high-pressure chamber of the pressure booster in the event of an undesired, increased leakage flow in the injector, for example by needle clamps, as a result of which a pressure booster piston assumes its maximum stroke. The throttle can also be formed by a correspondingly small line or a correspondingly small opening cross section of the check valve. In principle, the connection serves to refill the high pressure chamber of the pressure booster when the pressure booster piston is reset.

It can also be provided that the differential space of the pressure booster is connected to the high pressure space of the pressure booster via a second throttle and a non-return valve, the non-return valve releasing the flow of a fluid from the differential space to the high pressure space and the non-return valve the flow of a fluid from the high pressure space locks the difference space. The components mentioned therefore fulfill the same purpose as in the case of connecting the low-pressure chamber to the high-pressure chamber. The second throttle can also be omitted and the differential space of the pressure booster can be connected to the high pressure space via a check valve, since an undesired leakage flow in the injection Tor produces a pressure difference at the first throttle between the low pressure chamber and the differential chamber.

Particular advantages of the invention become apparent when the pressure booster interrupts a flow connection from the pressure accumulator to the injection nozzle when a certain stroke is reached. This prevents, for example in the event of jamming of the injection nozzle or jamming of the control valve of the injection nozzle, continuous injection and thus destruction of the engine. The pressure booster piston preferably has a pressure surface which is connected to the injector feed line even after the flow connection to the injector has been interrupted. Thus, the pressure booster piston remains at its end stop under pressure differential control. In this way, the corresponding injector is switched off in the event of damage.

It is advantageous if the inlet line is closed by a sealing device. The two components of the sealing device then lead to the closing of the feed line when the pressure booster piston has reached its maximum stroke.

However, it can also be advantageous if the filling path is closed by a slide seal. This slide seal can be formed by the pressure booster piston and the guide of the pressure booster piston. The supply line can thus be closed from a certain stroke, which depends on the point at which the fluid inflow starts at the high-pressure chamber of the pressure booster.

Elastic means for resetting the pressure booster piston are preferably provided. These can either be in Low pressure room, in the DJ conference room or in the high pressure room or at another suitable location. The elastic means can be implemented, for example, by a spring in the low pressure chamber.

Furthermore, it can be advantageous that at least one separate flow limiter is provided. According to preferred embodiments of the invention, the pressure booster acts simultaneously as a flow limiter. However, it may make sense to use a separate flow limiter. This can optionally be arranged, for example, in the filling path of the high-pressure chamber or between the pressure booster and the injector.

It can also be advantageous to provide a two-part pressure booster piston. The second valve unit, which connects the low-pressure chamber of the pressure booster to the differential chamber parallel to the throttle, can be dispensed with, since an overpressure in the differential chamber is prevented by the separation of the pressure booster pistons.

The invention is based on the generic method according to claim 17 in that the high pressure is generated by activating a pressure booster by opening a valve device connected to a differential space of the pressure booster and a return system and by limiting the flow rate of the fluid to an injection nozzle becomes. A control, that is to say an activation or deactivation of a pressure booster can thus take place by simply actuating a valve device while avoiding high relaxation losses. The flow rate limitation prevents damage to the engine, which is otherwise due to continuous injection could occur when the nozzle needle or the control valve of the injection nozzle is jammed.

The method is particularly advantageous if the maximum injection quantity is limited by the volume of a high-pressure chamber of the pressure booster. The pressure booster will therefore be beneficial! Used simultaneously for its primary purpose - pressure boosting - and, in the sense of intrinsic safety, to limit the flow rate.

However, it can sometimes be advantageous if the maximum injection quantity is limited by a separate flow limiter. This solution, which can also be provided in combination with a flow limitation of the pressure booster, is fundamentally more complicated. A separate flow limitation can, however, be advantageous with regard to the design of the pressure booster.

It is advantageous if the injector is stroke-controlled, it even being conceivable that the control valve of the injector is controlled by the same actuating element, preferably a piezo actuator, as the valve device which controls the pressure booster. In addition to a piezo actuator, a solenoid valve, for example, can also be provided as the actuating element.

The invention is based on the knowledge that a system with high intrinsic safety can be provided using a control of a pressure booster without large relaxation losses occurring. The pressure ^booster can thus optionally be activated, and injection course shaping can be carried out. For example, a pre-injection with low pressure and a Main injection take place at high pressure. For example, an advantageous “boot” shape of the injection pressure curve can be achieved.

drawing

The invention will now be explained by way of example with reference to the drawing using special embodiments.

FIG. 1 shows a first embodiment of an injection device according to the invention;

FIG. 2 shows a second embodiment of an injection device according to the invention;

FIG. 3 shows a third embodiment of an injection device according to the invention;

FIG. 4 shows a fourth embodiment of an injection device according to the invention;

FIG. 5 shows an injection device to explain the advantages according to the invention.

Description of the exemplary embodiments

FIG. 1 shows a first embodiment of an injection device according to the invention. An accumulator 10 provides primary pressure. This is fed to a pressure booster 12 in its low pressure chamber 14. In addition to the low-pressure chamber 14, the pressure booster 12 has a high-pressure chamber 16 and a differential chamber 18 on. The low pressure chamber 14 is connected to the high pressure chamber 16 via a throttle 20 and a check valve 22. The check valve 22 closes in the direction of the low-pressure chamber 14. The low-pressure chamber 14 is also connected to the differential chamber 18 of the pressure booster 12 via a throttle 24 and a check valve 26 connected in parallel therewith. The pressure booster piston 28 is acted upon by a spring 30 for the purpose of resetting. The check valve 26 blocks in the direction of the differential space 18.

To control the pressure booster 12, a valve device 32 is provided, which is connected to the differential space 18 of the pressure booster 12 via a connection. The other connection of the valve device 32 is connected to a return system 34. When the valve device 32 is closed, the pressure booster piston 28 is pressure-balanced, since the rail pressure prevailing in the low-pressure chamber 14 is established in the differential chamber 18 via the throttle 24. The pressure booster is deactivated, i.e. there is no pressure booster. As a result, injection with rail pressure is possible. The pressure booster piston 28 moves downward according to the injected quantity without pressure boosting. The pressure booster 12 thus works like a flow limiter. In particular, the pressure booster piston 28 has a valve seat 36 at its end, so that it closes the inlet line 38 to the injector 40 when it reaches its maximum stroke.

The injector 40 comprises an injection nozzle 42, the pressure chamber 44 of which is connected to the inlet line 38, which is connected to the high pressure chamber 16 of the pressure booster 12. The injector 40 is stroke-controlled, with a control valve 46 on the one hand with a return system 34 and on the other hand via an outlet throttle 48 with a control chamber 50 of the injection nozzle is connected. The ^τ control chamber 50 is also connected to the supply line 38 via an inlet throttle 52.

FIG. 2 shows a second embodiment of an injection device according to the invention. In contrast to the first embodiment according to FIG. 1, the differential space 18 of the pressure booster 12 is connected to the high pressure space 16 of the pressure booster 12. The refilling of the high-pressure chamber 16 thus takes place via this filling path. This too is provided with a throttle 56 and a non-return valve 58 blocking in the direction of the differential space 18, these components being connected in series.

FIG. 3 shows a third embodiment of an injection device according to the invention. This largely corresponds to the first embodiment of the invention shown in FIG. 1. The sealing seat or sealing device 36 (FIG. 1) for closing the inlet line 38 is, however, replaced by a slide valve 60 (FIG. 3), which closes the filling path 62 from a certain stroke of the pressure booster piston 28.

Figure 4 shows a fourth embodiment of the invention. A separate flow limiter 64 is provided in the connection between the low-pressure chamber 14 and the high-pressure chamber 18. Alternatively (or additionally), a flow limiter 66 is arranged in the connection between the high pressure space 16 of the pressure booster 12 and the injector 40. In the case of the on ^¬ of the flow restrictor order in the communication between the low pressure chamber 14 and the high pressure chamber 16 of the Druckverstarkers 12, a return valve is connected 68 to the Druckverstarker 64 in series back to a Druckuber- transmission from the high pressure chamber 16 into the low pressure chamber 14 to avoid , The preceding description of the exemplary embodiments according to the present invention serves only for illustrative purposes and not for the purpose of restricting the invention. Various changes and modifications are possible within the scope of the invention without leaving the scope of the invention and its equivalents.

Claims

Expectations

1. Injection device with an injection nozzle (42), a pressure booster (12) for increasing a primary pressure, a first valve device (32) for controlling the pressure booster (12) and an actuating element for actuating the first valve device (32), characterized that the pressure booster (12) is activated in a first state of the first valve device (32), that the pressure booster (12) is deactivated in a second state of the first valve device (32) and that a flow rate limitation to the injection nozzle (42) is provided is.

2. Injection device according to claim 1, characterized in that the pressure booster (12) has a low pressure chamber (14), a high pressure chamber (16) and a differential chamber (18), that the first valve device (32) with a first connection to the differential chamber ( 18) that the first valve device (32) is connected to a return connection (34) by a second connection and that the first valve device (32) is open in the first state, so that the differential space (18) is connected to the Return system (34) is connected.

3. Injection device according to claim 1 or 2, characterized in that the low pressure chamber (14) of the pressure booster (12) with the differential chamber (18) of the pressure booster (12) via a first throttle (24) and a second valve device (26) is connected, wherein the first throttle (24) and the second valve device (26) are arranged in parallel, the second valve device (26) enables the flow of a fluid from the differential chamber (18) to the low pressure chamber (24) and the second valve device (26 ) blocks the flow of a fluid from the low pressure space (14) to the differential space (18).

4. Injection device according to one of the preceding claims, characterized in that the second valve device is a check valve (26).

5. Injection device according to one of the preceding claims, characterized in that the pressure booster (12) closes an inlet line (38) to the injection nozzle (42) from reaching a certain stroke.

6. Injection device according to one of the preceding claims, characterized in that a sealing seat (36) is provided for closing the inlet line (38).

7. Injection device according to one of claims 1 to 5, characterized in that a slide seal (60) is provided for closing a filling path (62).

8. Injection device according to one of the preceding claims, characterized in that the low pressure chamber (14) of the pressure booster (12) is connected to the high pressure chamber (16) of the pressure booster (12) via a second throttle (20) and a check valve (22), the kickback valve (22) releases the flow of a fluid from the low pressure chamber (14) to the high pressure chamber and the check valve (22) blocks the flow of a fluid from the high pressure chamber (16) to the low pressure chamber (14).

9. Injection device according to one of the preceding claims, characterized in that the differential space (18) of the pressure booster (12) with the high pressure space (16) of the pressure booster (12) is connected via a check valve (58), the check valve (58) Flow of a fluid from the differential space (18) to the high pressure space (16) releases and the check valve (58) blocks the flow of a fluid from the high pressure space (16) to the differential space (18).

10. Injection device according to claim 9, characterized in that the differential space (18) of the pressure booster (12) with the high pressure space (16) of the pressure booster (12) is additionally connected via a second throttle (56).

11. Injection device according to one of the preceding claims, characterized in that elastic means (30) for resetting a pressure booster piston (28) are provided.

12. Injection device according to one of the preceding claims, characterized in that a two-part pressure booster piston is provided.

13. Injection device according to one of the preceding claims, characterized in that at least one pressure booster piston controls a flow connection to an injector (40).

14. Injection device according to claim 13, characterized in that the pressure booster piston interrupts a flow connection to the injector (40) in its end position.

15. Injection device according to one of the preceding claims, characterized in that at least one separate flow limiter (64, 66) is provided.

16. Injection device according to one of claims 1 to 14, characterized in that the flow rate is limited by the pressure booster (12).

17. A method for injecting fluid, in which a low-pressure injection takes place in a first phase and a high-pressure injection takes place in a second phase, characterized in that the high pressure is generated by activating a pressure booster (12) by a valve device (32) which is connected to a differential chamber (18) of the pressure booster (12) and a return system (34) is opened, and that the flow rate of a fluid to an injection nozzle (42) is limited.

18. The method according to claim 13, characterized in that the maximum injection quantity is limited by the volume of a high pressure chamber (16) of the pressure booster (12).

19. The method of claim 13 or 15, characterized in ^¬ net, that the maximum injection quantity by a separate flow restrictor (64, 66) is limited.