DK147951B - FUEL INJECTOR FOR DIESEL ENGINES - Google Patents

Description

This invention relates to a fuel injection plant for diesel engines and of the kind specified in the preamble of claim 1.

Such a valve-controlled fuel system is known from the specification of Swiss Patent No. 489,707. "In this known embodiment, the valves are arranged in a pump body, in which a pump piston, usually referred to as a plunger, is provided in a bore.

In the piston body, a pressure chamber is formed which is connected above a pressure valve to a transport line leading to an injection valve. Suction valves are arranged in an inlet duct in the pump body 9 which duct is connected to a supply line. An overflow valve controls the flow of the fuel into an overflow conduit in the pump body, which conduit is connected to an overflow conduit.

The plunger piston is driven over a camshaft on the guide shaft and a drive piston which also drives the valve body in the suction valve of the overflow valve over each pivotal guide bar. The control lever of the o-overflow valve is often pivotally mounted on an eccentric disk of an eccentric shaft, so that the pivot axis of the control bar is adjustable by turning the eccentric shaft about its main axis.

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Thereby the stroke length of the overflow valve and thus the end of the transport and the transport angle can be affected. The eccentric shaft can hereby be operatively connected with the motor's turnbuckle regulator, 147951 2 1, so that the amount of transport throughout the operation is controlled depending on the load. The control bar operating the suction valve is pivotal about a fixed pivot axis and is positioned relative to the drive piston 5 so that the beginning of the injection takes place a predetermined interval of time before the upper dead point of work not the st empathy.

High-performance diesel engines require large fuel-10 volumes in the part-load range as well. For thermodynamic reasons, these fuel volumes relative to the top dead center are injected earlier to meet the requirements for more economical consumption and stricter waste gas regulations.

Previous placement of the injection and ignition point causes the engine conditions during cold start to be adversely affected due to strong combustion noise, i.e. a strong knock. In addition, the steep pressure gradients associated with the knocking 20 and the high maximum pressures during combustion create an increased impact on and increased wear of the engine's drive.

From Danish Patent Specification No. 135-32, a fuel injection system for diesel engines is known, where it is possible to obtain a mode of operation with low rpm and yet inject a relatively large amount of fuel into the cylinders. It is also possible to adjust the fuel volumes to loads at lower 30 rpm than the operating speed. This is done by a setting mechanism that simultaneously delays the start time and end time of the fuel injection during operation, without changing the amount of fuel. This allows a fast acceleration of the engine, such as the engine. is necessary in case of emergency when fast steering a ship eg. to full power rear.

SUMMARY OF THE INVENTION The present invention aims to provide an injection system of the kind specified in the preamble of claim 1, wherein a temporarily delayed setting of the start of the fuel transport during a start-up period, and a subsequent reset to the most favorable adjustment of the fuel transport for normal operation. beginning is possible.

This is achieved according to the invention in that the injection system is designed as specified in the characterizing part of claim 1. By this design, it is achieved that during startup operation a delayed adjustment of the start of the fuel transport can be obtained and thus of the timing of the ignition during a heating period for the engine. This can avoid the steep pressure gradients, which otherwise occur at high performance, and the high maximum pressures during combustion, as well as the associated knocking and the increased impact on the engine's drive. Despite this, the previous ignition timing and associated benefits are maintained during normal engine operation. The plant also has the advantage of being simple, inexpensive and reliable and can be used in a variety of embodiments.

Conveniently, the system may be configured as claimed in claim 2. The piston-cylinder assembly may thereby be pneumatic or hydraulically operative. For large diesel engines, such as marine diesel engines and stationary diesel power plants, a pneumatic aggregate which can be integrated well into the pneumatic remote control of the engine must be preferred. The setting of the end position on the oscillating lever can be initiated by means of stops / and these are suitably adjustable within relatively wide limits. Thus, changes in the end position of the oscillating bar and thus of the start of transport, both for starting operation and also for normal operation, can be implemented in a simple manner.

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Preferably, as a timing measurement coupling, an outlet aperture is used, as defined in claim 3j, which may have a throttle body, a valve, a slider or an aperture and over which an emptying of the working medium is effected from the pressure space in the unit when in the initial operating position. . Emptying begins at the start of the start operation and takes place during this operating state at such a rate that the pressure in the pressure chamber of the unit after the elapsed predetermined start operating time ne-20 has decreased to a value at which the force affecting the piston on the pressure chamber side is less than a reset spring force acting on the second piston. This causes the piston to perform a reset stroke and move the pivot lever 25 back to the normal operating position.

Claims 4-6 indicate practical measures of the plant according to the invention, in particular for adjusting this.

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The invention will now be explained in more detail with reference to the drawing, in which FIG. 1 shows an embodiment of a fuel injection system according to the invention, partly shown as a block diagram, and partly in section; FIG. 2 shows an embodiment of the adjustment mechanism in normal operating position, with a plunger-cylinder assembly shown as a sectioning mechanism, a control valve and an emptying device as a timing measurement coupling, and FIG. 3 shows the mechanism of FIG. 2 in the initial operating position.

In FIG. 1, the fuel pump has a pump body 1, a pressure chamber 2 formed in this, a suction valve 3, an overflow valve 4 and a pressure valve 5. The suction valve 3 is located in an inlet duct 6 connected to a supply line not shown. The overflow valve 4 is arranged in an overflow channel 7, 20 connected to an overflow line not shown. The pressure valve 5 is inserted into an outflow duct 8 to which is connected a non-shown conveyor leading to a fuel injection valve not shown as well. A dive piston 9 25 is disposed in an axial bore relative to the pressure valve 5 in the pump body 1 displaceable against a spring force from a coil spring. The plunger piston is driven over a guide shaft 10 with a cam washer 10 ', a roller 11 and a drive piston 12. The drive piston 12 also drives a valve body 13 in the suction valve 3 over a control bar 15 and a thrust bar 16 as well as a valve body 14 in the overflow valve 4 over a control bar. 17 and a thrust bar 18. The guide bar 17 is pivotally mounted in a known manner on an outer shaft 23, whereby the pivot axis of the control bar 15 can be adjusted by turning about the main axis and also the lifting position of the suction valve 3 and affected. A pivot weight bar 24 fixed to the eccentric shaft 23 is pivotal about a major axis of the eccentric shaft 23 between two end positions 24 ^ and 24g. The end position 24 ^ is normal operating position and corresponds to an angular position of the eccentric disc 22 in which the 10 suction stroke produces a transport start during normal operation, whereas a position 24g is the initial operating position and corresponds to an angle position of the eccentric disc 22 in which the suction stroke produces a transport start at start operation.

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The swing lever 24 is connected to a setting mechanism 25 which moves it in a working stroke from a normal operating position 24 ^ to a starting operating position 24g and in a reset stroke from this position 24g to the normal operating position.

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The tuning of the setting mechanism 25 to the end positions 24 ^ and 24g of the swing bar 24 determined by a calculation is initiated by two devices 26 and 27, of which the device 26 serves for setting the starting operating position 24g and the device 27 for setting the normal operating position 24n · The devices 26 and 27 are adjustable 30 in an area between set limits.

The adjusting mechanism 24 is additionally connected to a control device 28 which outputs control signals SA and the seven reset reset stroke for the setting mechanism 25.

A timing measurement coupling 29 communicates with the control device 28 and, after the course of a desired start-up operation, emits a signal SD which releases a reset signal S 1.

When a signal S may be applied to the control device 29, which may be a signal generated at the start of the motor or a signal generated by the manual switching on of a signal source, the working stroke of the setting device 25 is triggered and the oscillating lever 24 is brought into its starting operating position 24g. In addition, S is applied to the timing measurement coupling 15 29, the signal initiating the measurement of the start operating time and after the expiry of the desired start time, a signal SD delivers to the control device 28, thereby supplying a reset signal for setting stroke, so that the oscillating lever 24 is moved back to its normal position 24 ^.

A device 30, which is associated with the timing measurement coupling 29, may also be provided for setting the startup operating time. This device 30 may also have the function of receiving operating parameters describing the instantaneous engine load or fuel quality and of calculating and adjusting the starting operation time by these parameters and adding this time to the timing measurement switch 29 in the form of a signal S 1.

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According to FIG. 2 and 3 there is a piston-cylinder assembly 31 which operates with air as a working medium, which acts as a setting mechanism, a pneumatic control valve 35 which acts as a control device, and a discharge device 4L, whose outlet cross section is adjustable, and which acts as a time measurement link. One of the two guide elements 33, 34 comprising a rod system transmits the movement of a piston rod in the assembly 31 to a pivot lever 24 not shown in FIG. 2 and 3. A stop 36, which consists of two nuts and is adjustable on the piston rod 32, limits the working direction stroke of a piston 37 to the drawing 10, thereby serving to set the starting operating position 24g of the pivot lever 24. An outer thread, second assembly 31, is retained with a nut 39 relative to the assembly 31. The abutment restricts the reset stroke to the left in the drawing and thus serves to set the normal operating position 24 ^ of the pivot lever 24.

20 The control valve 35 designated as control device 28 is shown in FIG. 2 in its normal position and in FIG. 3 in its starting position. In the normal position, the control valve over a conduit 48 connects a pressurized pressure chamber 40 in the assembly 31 with the emptying device 25 41, whereas in its initial position the control valve connects the pressure chamber 40 with a pressure source not shown connected to the valve 35 via a conduit 42. The control valve 35 is, by means of a start signal S, automatically supplied over a line 43 or 30, by means of a pushbutton 44, displaceable from its normal position to its starting position. In the starting position of the valve 35, the pressure chamber 40 is constantly pressurized, as the piston 37 performs its limited stroke by means of impact and also the swing bar 24 in its starting operating position 24g. Thereby, air on the other side of the piston 37 escapes over a vent bore 47 in the assembly 31. As soon as the signal S is interrupted, the control valve 35 is reset to its normal position, by means of its reset spring 46, in which a pressure chamber 40 is emptied. little by little above the emptying device and thus an even pressure drop is obtained in the pressure chamber 40. The outlet cross-section of the device 4l is adjusted so that the pressure in the pressure space after the desired starting operating time has just dropped to a value at which it acts on the piston 37 on the pressure chamber side. force is less than the force exerted by a reset spring 45 on the second piston side. The piston 37 will then perform a reset stroke and return to that of FIG. 2, while the pivot lever 24 reaches its normal operating position 24n.

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The adjusting mechanism 25 for pivoting the pivot lever 24 may have an electromagnet with a rectilinear displaceable core or an electric adjusting motor. The control device 28 and the devices 25 and 29 are then electrical and / or electronic couplings, with certain input sizes e.g. the temporal position of the drive piston 12 must be supplied as electrical signals.

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Claims (3)

147951 ίο 1. Fuel injection system for diesel engines with a valve-controlled fuel pump (1) with a pump cylinder with a plunger (9) * driven via a drive mechanism by a control shaft (10), and comprising an overflow valve (4) which determines the end of the fuel transport and a suction valve (3) which determines the beginning of the transport and whose valve body is driven by a drive mechanism over an eccentric shaft (22, 23) pivotally mounted (10) pivot lever (24) fixedly attached to the eccentric shaft (22, 23) and which can be swiveled about the main axis thereof with two positions, one being the operating position of the pivot lever (24 ^) and the other being the starting position (24g), as well as an adjusting mechanism (25) actuated by a control mechanism, for moving the swing bar (24) from one position to another, characterized in that the swing bar (24) via the setting mechanism (25) and as a function of a motor start signal (S independently of the instantaneous position of the overflow valve (4) is pivotable from the operating position (24n) to the starting position (24β) and, after the expiry of a preset start phase period which is independent of the engine speed, is reversible to the operating position (24 ^). as a function of a reset signal (SR) and wherein the start phase period is monitored by an adjustable timing switch (29) which controls a control device (28) which triggers the reset signal (Sn), the operating position 30 (24jj) of the swing weight rod ( 24) corresponds to the settings of the eccentric shaft (22, 23) where the suction valve stroke, upon expiration of the start-up phase, produces a time-shifted fuel transport and where the starting position (24s) of the oscillating lever (24) corresponds to that of the eccentric shaft (22, 23). ) angular positions where the suction valve produces a start-phase fuel transport. System according to claim 1, characterized in that the adjusting mechanism (25) has a piston-cylinder assembly (31) influenced by a pressure medium and that an adjustable stop (24g) is provided for determining the starting position (24g) of the pivot lever (24). 36) which restricts the working stroke 15 (31) and that in order to determine the pivot weight of the rod (24) operating position (24 ^) on the cylinder there is another adjustable stop (38) which restricts the reset stroke of the piston (37). 20 ' System according to claim 1 or 2, characterized in that the control device (28) has a control valve (35) which, as a function of a start signal (S), is displaceable from an operating position to a starting position, where the control valve produces a connection. separation between a pressure chamber (40) in the assembly (31) and a pressure source, to pressurize the pressure chamber (40) shockingly, and the control valve (35) automatically switches back to its operating position where the control valve produces an interruption of the starting signal (S). a connection of the pressurized pressure chamber (40) with an outlet opening (4l) and initiates the emptying of the pressure chamber, after which the control valve remains in its