DE3234049A1 - Injection time adjustment compensation device for a fuel injection pump - Google Patents

Abstract

A pressure-sensitive element is operationally connected to a pressure regulating device by way of a cam section of a control pin and a follower pin. The pressure regulating device regulates the fuel pressure inside a chamber of a pump housing as a function of a pressure change which acts upon the pressure-sensitive element in order thereby to compensate a fuel injection control which is determined by an injection time control element. The pressure acting on the pressure-sensitive element is an atmospheric pressure or a charging pressure. The pressure regulating device is adjustable so as to speed up or retard the injection time according to an atmospheric pressure or a charging pressure or the point may be varied at which the fuel pressure in the pump chamber begins to change.

Description

Injection time adjustment compensation device for a fuel injection pump

description

The invention relates to a fuel injection pump, which can be designed as a distributor design, but does not necessarily have to be, and in particular the invention relates to a device for compensating a fuel injection time such a pump.

If an internal combustion engine, in particular a diesel internal combustion engine is so designed and constructed that it can be used at normal low sea levels is determined and if such a Brennkraf t- <machine at high sea levels such as when driving a vehicle is supposed to work, occurs as a result of the thin Excessive fuel supply, causing Not only does the fuel economy deteriorate, but also smoke is emitted, which leads to environmental pollution leads. It is therefore necessary to control the fuel injection both in terms of quantity and also to compensate the point in time depending on the change in air density, which is its cause in a Change in atmospheric pressure.

Nowadays there is a trend in the field of internal combustion engine construction, turbochargers or similar charging devices to increase the output power of the internal combustion engine and to improve fuel economy to use. In the case of an internal combustion engine with supercharging, the injection quantity must be such

can be set to be an amount of intake air fits, which is fed to each cylinder of the internal combustion engine via the supercharger. The injection time must, for example, depending on the output power and the thermal load on the internal combustion engine being controlled.

It has heretofore been proposed a device for compensating the fuel injection amount, the

-Q turns out to be an atmospheric pressure compensation device or a boost pressure compensation device can be typified in more detail. But a device capable of the time of fuel injection as a function To change from atmospheric pressure or from boost pressure, however, is not previously known in this field.

A fuel injection pump with a feed pump driven by an internal combustion engine, which under '"Conveys fuel under pressure to a chamber, which is limited inside a housing of the pump, an injection time control element, which is controlled by a Fuel output pressure of the feed pump as a function can be operated by an internal combustion engine speed and a fuel control element is characterized by

"E a pressure control device that controls a fuel pressure in the chamber of the pump housing regulates that the fluid connection between the chamber and a with the low-pressure side connected to the pump is controlled, and a pressure-sensitive actuator that the pressure control device is actuated via an operating connection as a function of an applied pressure, off, with a point in time for the fuel injection, which is determined by the fuel injection control element, via the injection time control element in a matched mood can be compensated with a pressure level which acts on the actuating device.

According to the invention is a pressure sensitive element operationally connected to a pressure control device via a cam portion of a control pin and a follower pin. The pressure regulating device regulates a fluid pressure in the interior of a chamber of a pump housing Dependence on a change in a pressure acting on the pressure-sensitive element. This will compensated for an injection time which is determined by an injection time control element. The one on the printing

jQ sensitive element acting pressure is an Afcmospluh r pressure or a boost pressure. The pressure regulator is either in the sense of a lead or a lag the injection time adjustable in accordance with an atmospheric pressure or a boost pressure, or he can change the point at which the fuel pressure in the pump chamber begins to vary.

The invention aims to provide a novel injection time adjustment compensation device for a Kraft-2Q fuel injection pump of the type described above create that allows the timing of fuel injection is automatically adjustable depending on an atmospheric pressure or a boost pressure.

2g Furthermore, an injection time adjustment compensation device is intended for a fuel injection pump of the introduction described type be such that the injection time can be compensated in an adjustable manner is.

In particular, according to the invention, a simply designed but effectively working injection time adjustment compensation device is intended created that have no influence on the design of a fuel

gg control device has.

Further details, features and advantages of the invention emerge from the following description of a Preferred embodiment with reference to the accompanying drawings. It shows:

Fig. 1 is a vertical sectional view of a fuel 6InSprItZpUItIPe ₇ for which the invention is intended,

IQ Fig. 2 is a schematic horizontal sectional view

the fuel injection pump of Fig. 1,

Fig. 3 is a vertical sectional view of an injection

time adjustment compensation device according to an embodiment according to the invention

manure,

Fig. 4 is a diagram to illustrate an input

injection time advance, which is achieved with the injection time adjustment compensation device after

the invention is achievable, and

Fig. 5 is a schematic vertical sectional view a further embodiment according to the invention.

Although the injection timing controller for a fuel injection pump in the present invention apf trained in a variety of ways depending on the environment and the requirements of the application can be, a larger number of the shown and described preferred embodiments were produced, tested and used and found all to work extremely satisfactorily.

-Χ Ι In Figs. 1 and 2 of the drawing, a fuel injection pump of the distributor type is shown for which the invention is intended, and which is designated as a whole with 10. The fuel injection pump 10 has a housing 12. A plunger or piston 14 distributes a controlled volume of fuel, which is under pressure, to each cylinder of a multi-cylinder internal combustion engine via an output valve 16. For this purpose, the plunger 14 is rotated about its axis with the aid of a

jQ cam 18 rotated and at the same time he is along its axis due to the sliding contact of a cam surface of the cam plate 18 with rollers 20a which supported by a roll holder 20, reciprocated. The cam disk 18 is operational

■ ^ 5 connected to an input shaft 21, which in turn is driven by the internal combustion engine.

Inside the housing 12 there is a chamber 12a into which a fuel to be pumped by the plunger 14 is located is introduced via a feed pump 22. The amount of fuel supplied to the chamber 12a changes depending on the operating speed or the speed of the internal combustion engine. Part of the Fuel is fed into a timing device (not shown) located at the bottom of the housing 12 is located. The timing device has a control piston 24 and a control spring 26 and it is connected to the roll holder 20 via a rod 28 which is shown in detail in FIG. The control piston 24 is a function of the fuel inlet pressure displaceable against the action of the control spring 26.

The fuel pressure generated by the feed pump 22 moves the control piston 24 in the timing device, which in turn moves the roller holder 20 in the angular direction emotional. This changes the relative

-Λ-

Contact position between the rollers 20a and the cam surface of the cam plate 18 and therefore changes Relationship between the circumferential phase of the input shaft 21 and the working position of the plunger 14, wherein the injection time of the fuel is controlled by the pump. In the illustrated type of pump 10 the ignition point setting is adjusted in the sense of an advance when the control piston 24 counter to the left " the control spring 26 in FIG. 2 is displaced.

Flyweights 30 are set in rotation by the input shaft 21. As a result of the rotational movement of the flyweights 30, a control rod or a control shaft 32 is moved relative to the housing 12 to an extent that is dependent on the speed of the internal combustion engine. A starting lever 34 is rotatably mounted on a bolt 36 provided on the housing 12. .... A control sleeve 38 is slidable on the plunger 14 and (not shown) provided with a recess, i ⁿ which a bolt 40 is engaged on an end of the start lever 34th A start spring 42 is fixedly connected to the other end of the start lever 34 to keep the same in constant engagement with the end of the control linkage 32. A pull lever 44 is also rotatably mounted on the bolt 36, which holds the starting spring and is rotatable about the bolt 36 together with the starting lever 34 to form a unit with the movement of the control rod 32. The pull lever 44 is pressed by an idle spring 46 and a control spring 48. The control spring 48 is anchored at its other end to a shaft 50 on a control lever 50a, which can be operationally connected to the accelerator pedal or accelerator pedal of a motor vehicle. When the control lever 50a is in a starting position or in a position for the maximum speed of the internal combustion engine, the control spring 48 pulls the tension lever 44 until the latter is in

Engagement with a full load stop (not shown) on the housing 12 comes. The power of the control spring 48 is larger than that of the idle spring 46, but that stronger than that of the starting spring 4 2. The start lever 34 or the pull lever 44 is rotated around the control sleeve 38 to move along its axis over the bolt 40, in order to thereby the fuel delivered by the pump 10 to control injection quantity. In full load operation, the position of the full load stop can be adjusted by the Set the operating position of the pull lever 44 and thereby the amount of fuel to be injected.

In Fig. 3 a device according to the invention is shown, the fuel injection both with respect controls the amount as well as the point in time depending on an atmospheric pressure. The device has a housing 52 which is attached to the upper part of the pump housing 12 in a fluid-tight manner. One lid 54 is on the top of housing 52 via an O-ring 56 attached to delimit a control chamber 58. The control chamber 58 is connected to the atmosphere through an atmosphere port 60 connected, while in terms of fluid flow from the pump chamber 12a through a Intermediate portion 52a of the housing 52 is isolated.

A sleeve 62 is fixed in the intermediate housing section 52a and a control pin or plunger is provided in the sleeve 62 so as to be axially slidable. A metal bellows or similar pressure sensitive element 68 is arranged in the control chamber 58.

A rod extending from the bellows 68 is received in a bore 64a at the top of the control pin 64 is formed. A spring 70 is between the bottom of the control chamber 58, which is of the Housing section 52a is limited, and a spring seat 72 clamped, which is mounted on the control pin 64.

\ λ

The spring 70 constantly acts on the rod of the bellows 68 with a compressive force upwards, so that the upper part of the The rod remains in abutment contact with a set screw 74 which is screwed into the cover 54. The position the adjusting screw 74 determines the axially ineffective

Position of the control pin 64. The bellows 68 is dependent ^ - ability of a change in the associated atmospheric pressure expandable, thereby reducing the axial position of the control pin 64 is variable. The interior jQ of the bellows 68 is evacuated to allow for a change in atmospheric pressure easy to record and to minimize the effects of temperature changes keep.

The control pin 64 is, as indicated at 64 b, partially conical downwards. A follower pin 76 extends through the intermediate housing abscTinitt 52a to to be movable in the transverse direction and in engagement with the conical portion or the cam portion 64b on one To be the end. The other end of the follower pin 76 is located against a surface of a lever 78 which is pivotally mounted on the housing 52. The lever 78 is constantly in engagement with one end of the pull lever 44, the other end of which is connected to the control sleeve 38 is, as mentioned earlier.

A pressure regulating device, indicated generally at 80, has a body 82, the one therein located bore 82a has. A valve element 84 is slidably disposed in the bore 82a, and one Spring 86 is disposed between body 82 and valve 84 within bore 82a. The body 82 is screwed into the housing 52 below the intermediate housing part 52a with a connection 88 in between.

The connection 88 is shaped so that it has an annular chamber 88a forms in cooperation with the body 82,

which are in fluid communication with a fuel reservoir or the like. On the low-pressure side (not shown). The body 82 has two passages 82b and 82c, each of which extends to the annular chamber 88a at one end and to the bore at the other end 82a open. The valve element 84 is provided with an axial passage 84a which communicates with the pump chamber 12a and the bore 82a is connected at the opposite ends. Two radial passages 84b extend

IQ extends from the axial passage 84a to the outer periphery of the element 84. The axial passage 84a extends through the entire valve element 84 so that high pressure can be introduced into the bore 82a to maintain a pressure balance. The valve element 84 is constantly in contact with the other side of the lever 78. A basic position or an inoperative position of the valve element 84 is selected such that the radial passages 84b are in communication with the passages 82b and 82c of the body 82, respectively. In such a position of the valve element 84, ie as long as the device is not actuated, the pressurized fluid in the interior of the pump chamber 12a flows to the low-pressure source via the valve element 84, the body 82 and the connection 88.

To explain the mode of operation it is assumed that a motor vehicle with a device of the embodiment described above a high altitude such as when driving uphill, for example. A drop in atmospheric pressure then causes the bellows to expand 68 expands to push the control pin 64 downward, with the follower pin 76 following in FIG is moved to the left by the conical portion 64b of the control pin. The follower pin 76 in turn pushes the lever 78 in Fig. 1 in the counterclockwise direction, so that the pull lever 44 clockwise around the bolt

-JO- ·

36 is rotated to axially to the left of the control sleeve, i.e. in the direction of a smaller amount of fuel move- As a result, the amount of fuel injection delivered by the pump 10 becomes proportional to the rate of decrease in air density is reduced.

While the follower pin 76 moves to the left, the valve element 84 of the pressure regulator 80 is alImSh- - borrowed via the lever 78 against the action of the spring 86 pressed to the left. Then the radial passages 84b moved beyond the associated passages 82b and 82c, until they pass through the inner wall of the Bore 82a of the body 82 are blocked. This prevents the pressurized fuel from flowing over from the pump chamber 12a to the low pressure side interrupted so that fuel pressure inside the Pump chamber 12a and therefore the fuel pressure acting on the timing piston 24 gradually increases. Consequently, the control piston 24 in Fig. 2 is pressed against the force of the control spring 26 to the left, which the Roll holder 20 rotated in a direction to advance the injection time. Thus, the timing of fuel injection becomes from the pump 10 in the sense of an advance as a function of the atmospheric pressure drop adjusted. Herein is an effective countermeasure against an increase in emissions of poisonous hydrocarbons seen as a result of a decrease in airtightness.

Such an injection time adjustment in the sense of an advance is shown in a curve in FIG. 4, where on the ordinate a fuel pressure Pt inside the pump chamber 12a and on the abscissa an atmospheric pressure Pa is applied. It's over This figure shows that a desired adjustment of the injection time in terms of an advance

AU

to an atmospheric pressure thereby be achieved appropriately in that accordingly the cross-sectional areas of the passageways in the body 82, _<he fi radial passages in the valve element 84, etc. selected.

The design according to FIG. 3 can be modified in such a way that the fuel injection quantity can be increased and the ignition point setting can be adjusted as a function of a boost pressure in the sense of a presetting. In such a modified embodiment, the bellows 68 is replaced by a membrane actuating device known per se, and a boost pressure is applied to the actuating device via the connection 60. Displacement of the diaphragm by boost pressure will turn the pull lever 44 counterclockwise at this point. As shown in the Ausführungsforin, the pressure regulator 80 is arranged and designed such that it outputs the radial 84b of the valve element 84 simultaneously with the actuation of the

Pull lever 44 closes. In the modified version -

form, the valve element 84 can be arranged such that its radial passages 84b are normally closed and that they open when the diaphragm is opened shifts so that the injection time in terms of a Lag can be adjusted when the atmospheric pressure drops and since it can be adjusted in the sense of a preset leaves, the atmospheric pressure increases. This also allows an opposite to that described above Realize embodiment effective mode of operation if necessary in an internal combustion engine.

In Fig. 5 a further embodiment according to the invention is shown. In Fig. 5, a pressure regulating device has 100 a body 102 which is axially adjustable relative to a valve element 104. The body

is threaded at opposite ends and in intermediate housing portion 52a on one threaded end screwed in. A lock nut 106 is threadedly engaged with the other end of the body 102 to firmly connect a connection 108 to the housing 52. The too extreme end of the body 102 is provided with a groove 102b into which a screwdriver or a similar tool can be inserted is. The body is provided with two passages 102b and 102c, each in communication with a bore 102a and an annular chamber 108a. The valve element 104 is slidably received in the bore 102a and is constantly by a spring 110 of the Bore 102a pushed outward.

In the pressure regulator 100, the body 102 is in a desired position relative to the valve element axially movable by loosening the lock nut 90 and rotating the body 102 about its axis. The desired Position can be chosen so that in the basic position or in the inoperative position of the follower pin 76, the radial passages 104b in the valve element 104 in communication with the passages 102b and 102c are in body 102 or vice versa so that in the same position of pin 76 the radial passages 102b and 102c can be decoupled. In addition, the radial passages 104b can begin with the passages 102b and 102c and a desired value of the atmospheric pressure or the boost pressure come or part with it. This point in time corresponds to a point on the Pt-Pa curve in Fig. 4, at which the pressure Pt in the pump chamber 12a begins to change.

Although the pressure control device 80 in Fig. 3 or

his,

-Π Ι in Fig. 5 is such and designed that the

Movement of the follower pin 76 on the associated Elements is transmitted via the lever 78, represents the position shown of the pressure control device in the Proximity of the lever 78 is not a restriction. For example, a follower pin can be independent of the follower pin 34 be arranged in a position which is at an angular distance of 90 ° horizontally from the position which is shown in Fig. 3 so that the valve element 84 rests directly against the stylus.

In summary, it can be seen that the invention has a simply designed and yet effectively working form of training, which enables the control j ^ g of fuel injection in different ways in Dependence on atmospheric pressure or a boost pressure without influencing the design and the mode of operation a fuel control device is adjustable.

Claims (6)

Claims 1 / injection time adjustment compensation device for a fuel injection pump with a feed pump ₇ driven by an internal combustion engine that delivers pressurized fuel to a chamber that is limited inside a housing of the pump, an injection time control element that is controlled by a fuel output pressure of the feed pump as a function of an internal combustion engine speed is operable and a fuel control element, characterized by: a pressure regulating device (80, 100) which controls a fuel pressure in the chamber (12a) of the pump housing (12) thereby regulates that the fluid connection between the chamber (12a) and one connected to the pump (10) Low pressure side is controlled, and a pressure sensitive actuator (68)., The the pressure regulating device (90, 100) via an operating connection as a function of an applied pressure operated, wherein a timing for fuel injection, the determined by the fuel injection control element via the injection timing control element (24) in accordance can be compensated with a pressure level which acts on the actuating device (68). 2. Apparatus according to claim 1, characterized in that g e k e η η ■ records that the on the pressure sensitive actuator (68) applied pressure is atmospheric pressure and that the actuating device one off Has metal existing bellows. 3. Apparatus according to claim 1, characterized in that the on the pressure-sensitive actuating device (68) acting pressure is a boost pressure and that the actuating device (68) is a Has membrane element. 4. Apparatus according to claim 1, characterized in that the pressure control device (80, 100) a body (82, 102) supported on a housing (52) of the device is attached, as well as a spring-loaded Valve element (84, 104) slidably disposed in a bore (82a, 102a) of the body (82, 102) is, and that each of the body (82, 102) and the valve element (84, 104) are provided with passages (82b, 82c; 102b, 102c; 84a, 84b; 104a, 104b) are provided, the optionally pump chamber (12a) with the low pressure side associate. 5. Apparatus according to claim 4, characterized in that the body (102) in its position relative to the valve element (104) is adjustable. 6. The device according to claim 1, characterized in that the operational connection between the pressure regulating device (80, 100) and the pressure-sensitive actuating device (68) has a vertically reciprocating control pin (64) which is partially conical to form a cam part (64b) and a follower pin (76) which cooperates with the cam part (64b) transversely to the control pin (64) so that the pressure regulating device (80, 100) contains a body (82, 102) which is mounted on a housing (52 ) is attached to the device, further a valve element (84, 104) which is arranged in a bore (82a, 102a) of the body (82, 102) and contains a spring (86) which the valve element (84, 104) of the body (82, 102) is preloaded to the outside, so that the body (82 _T 102) and the valve element (84, 104) are provided with passages (82b, 82c ...), which optionally the pump chamber ( 12a) with the low pressure side, and that the control pin (64) e instückig is connected to the pressure-sensitive actuating device (68), while the follower pin (64) is arranged in such a way that it presses the valve element (84, 104) against the action of the spring (86).