JPH0650238A - Fuel injection pump for internal combustion engine - Google Patents

Abstract

PURPOSE: To achieve cost-effective manufacturing and mounting by forming a cylindrical part on an entraining pin for varying the travel position of an annular slide and press-fitting the part in a bore of an adjustable shaft. CONSTITUTION: To operate an annular slide 17 axially on a pump piston 7, the slide 17 is provided with a recess 43 at the opposite side of a web 19, and an entraining pin 45 which is an eccentric pin is engaged at a head piece 47 thereof. A cylindrical part 49 of the entraining pin 45 is formed by a slide fit seating section 61 having a diameter slightly less than a press fit seating section 57 starting from an end face 35. The slide fit seating section 61 is adjacent to a shaft portion 63 arranged eccentrically with respect to a neck portion 65, and concentrically coupled with the head piece 47. The entraining pin 45 is press-fitted into a radial bore 51 which is slightly less than the press fit seating section 57 of an adjustable shaft 53. In this case, it is possible to adjust the precise rotational position of the entraining pin i.e., the eccentric position thereof, hence the travel starting position of the annular slide 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a fuel injection pump of the type described in the preamble of claim 1.

[0002]

2. Description of the Prior Art In a fuel injection pump of this type, known from DE-OS 3546222, a plurality of pump pistons arranged in rows are guided in cylinder bores of a cylinder bushing. Moreover, the cam drive mechanism reciprocates in the axial direction. In this case, axially slidable annular sliders are arranged on the pump piston, which cooperate with the control passage of the pump piston for the purpose of controlling the high-pressure delivery. These annular sliders are operated via an adjusting shaft which is guided transversely to the pump piston axis in the pump casing. In this case, the rotational movement of the adjusting shaft is transmitted to the annular slider via the driving pin which is inserted into the radial hole of the adjusting shaft and whose end is engaged in the notch of the annular slider, As a result, axial sliding of the annular slider occurs there. In order to adjust the travel start positions of the individual annular sliders relative to one another, the drive pins are designed as eccentric pins in known fuel injection pumps and penetrate into the recesses of the annular slider of the eccentric pins. The head is eccentrically arranged with respect to the shaft of the pin, which is passed through the adjusting shaft. As a result, the rotation of the eccentric pin adjusts the stroke starting position of the individual annular slider. In this case, the eccentric drive pins are tightened against the adjusting shaft via the tightening nuts arranged on the drive pins after adjusting the pivotal positions of the drive pins and thus the automatic rotation of the drive pins. Movement is prevented. However, such a fixed form has the disadvantage of high material and manufacturing costs due to the use of additional structural parts.

[0003]

The fuel injection pump according to the invention having the features of claim 1 maintains its functional reliability and the adjustability of the stroke positions of the individual annular sliders sufficiently and requires a small number of structural parts. However, this has the advantage that cost-effective fabrication and installation is possible. This advantage is obtained by the fact that the drive pin, which serves as an adjusting element, is integrally molded and is tightened by a press connection with the adjusting shaft. In this case, the adjustment of the travel position of the individual annular sliders is effected by the rotation of the drive pin, which is designed as an eccentric pin. According to claim 2, the entrainment pin has a cylindrical part which is inserted into the bore of the adjusting shaft and has a sliding seat and a press-fitting seat. The seat allows the cylindrical part to be pivotally guided or clamped into the bore of the adjusting shaft. In this case, the sliding seat has a slightly smaller diameter than the axially following press-fit seat, so that the pivot position can be adjusted without great expense. The structure of the cylindrical seat therefore allows easy assembly of the drive pin and adjustment of the pivot position, as well as a push fit of the drive pin into the adjustment shaft which is technically satisfactory. In order to provide a precise interrelationship between the pivot position of the drive pin in the adjustment shaft and the travel position of the annular slider, according to claim 3, the marks are arranged on the drive pin and the adjustment shaft. The above-mentioned mark provides a relation between the pivotal position of the drive pin with respect to the adjusting shaft and the travel position of the annular slider. Therefore, after measuring the variation of the delivery start timing between the individual members by using the master shaft, the first driving pin is fixed as the starting position on the adjusting shaft to be assembled and the first driving pin and the individual driving pin are fixed. In connection with the variation in the stroke position of the other driving pins, it is possible to position and fix the other driving pin in the adjusting shaft for the uniform fuel delivery start timing. In order to ensure a positive guide of the drive pin in the notch of the annular slider during the adjustment of the travel position of the drive pin, according to claim 4, the part of the drive pin that penetrates into the cutout. Is configured as a spherical segmented head, the contact edge of this head with the horizontal edge limiting the notch being configured as a curved edge, so that which adjustment position of the annular slider is adjusted. However, a uniform pivoting surface is ensured by the entrainment pin. Furthermore, this avoids the locking of the head in the recess of the annular slider during the stroke movement and the associated inaccurate adjustment. This is claim 5
According to the invention, it is supported by an advantageous design of the neck and shank for connecting the head to a cylindrical part which is passed through the adjusting shaft, which has a reduced diameter with respect to the cylindrical part. In this case, the spherical head of the drive pin is concentric with the shank, which shank is further eccentrically connected to the neck which is connected to the cylindrical seat. As a result, this tapered coupling shank creates a groove in the entrainment pin which prevents the entrainment pin from hitting the annular slider during travel adjustment of the annular slider. The structural features according to claims 6 to 9 in which the size of the hole in the adjustment shaft and the size of the entrainment pin are described are that the assembly of the entrainment pin and the adjustment of the rotational position are performed from the side opposite to the annular slider side. It has the advantage that it is not disturbed by adjacent structural parts. As a further advantage, according to claim 10, the transition between the neck and the sliding seat is constituted by a chamfer, so that secure and easy assembly is possible without locking. In order to make it possible to engage with the driving pin as easily as possible during the process of adjusting the position of the driving pin by the shaping tool, according to claim 11, a shaping connection surface is formed on the end face of the driving pin opposite to the annular slider side. Has been done. A further advantage is obtained by the sliding seat being conically shaped, as claimed in claim 12. This is because the cross-section of the drive pin, which gradually expands in the direction of the press-fit seat, ensures a uniform tension during the press-fit of the drive pin in the bore of the adjusting shaft.

[0004]

1 shows a fuel injection pump only to the extent that it is important for the invention, in which a cylinder bush 3 having a cylinder bore 5 is inserted in the pump casing 1. A pump piston 7, which is moved in the axial direction by a cam drive mechanism (not shown), is guided in the cylinder hole 5, and the pump piston has a cylinder bush at an end surface 9 opposite to the cam drive mechanism side. The pump working chamber 11 is restricted within 3. This pump work room 1
1 is connected via an injection conduit (not shown) to an injection valve which projects into the combustion chamber of the internal combustion engine to which fuel is to be supplied. A cylindrical notch 13 is arranged in the cylinder bush 3 and is open laterally with respect to the low-pressure chamber 15 and slides axially on the pump piston 7 in the notch 13. It encloses a movable annular slider in a shell shape. This annular slider 17 is provided with a notch 13 in a longitudinal groove 23 arranged in an inner wall 21 formed by a cylindrical notch 13 of a cylinder bush 3 via a web 19 radially protruding from the outer circumference thereof. Is engaged in the range of, and is therefore fixed so as not to rotate. This annular slider 17 comprises a lower end surface edge 25 which serves as a control edge and two radial control holes 27 which are diametrically opposed to each other on the peripheral wall of the annular slider.
And have. To these control holes, two inclined grooves 29 are formed which are formed axially symmetrically as control notches on the outer peripheral surface of the pump piston 7. These inclined grooves rise at a certain angle with respect to the longitudinal axis of the pump piston 7 and have one flat bottom surface 31 and two parallel extending limiting surfaces. These limiting surfaces form control edges that are inclined with the outer peripheral surface of the pump piston 7, and the upper control edge 33 of these control edges is on the pump working chamber 11 side. Flat bottom surface 3 of the inclined groove 29
At the center of 1, a lateral hole 35 extends through the pump piston 7. The lateral hole 35 opens into a blind hole 37 that starts from the pump working chamber 11 and extends axially in the pump piston 7, and the blind hole 37 together with the lateral hole 35.
A passage 39 is formed between the flat bottom surface 31 of the inclined groove 29 and the pump working chamber 11.

In order to operate the annular slider 17 on the pump piston 7 in the axial direction, the annular slider 17 has a cutout 43 on the side opposite to the web 19 side. An entrainment pin configured as an eccentric pin engages at its head 47. Said entrainment pin 45 is passed transversely to the pump piston axis and through a cylindrical seat 49 into a bore 51 of an adjusting shaft 53 guided in the pump casing and radially. It projects from the adjustment shaft. The hole 51 is a component of the stepped hole 71 and has a smaller diameter here. Furthermore, the drive pin 45 is designed as an eccentric pin, as shown enlarged in FIG. 2, which drive pin is divided into two main areas. In this case, one main area consists of a cylindrical portion 49, as shown in FIG. 2, which press fitting seat starting from the end face 55 opposite the head 47 side. 57
And a sliding seat 61 having a diameter slightly smaller than the press-fitting seat 57. A neck portion 65 having a reduced diameter is connected to the sliding seat 61 through a chamfered portion 59 in the direction of the head portion 47. Adjacent to the other side of the neck is a shank 63, which is arranged eccentrically to the neck, the diameter of the shank is reduced once more, and the shank extends to the head 47. They are connected concentrically. Head 4
7 is configured as a sphere segment, the end face of the sphere segment on the side of the shaft 63 and the end face 69 located above and opposite to this axis being flat, in this case occurring The flat surface extends perpendicular to the axis of the drive pin 45. The entrainment pin 45 is pressed into the radial bore 51 of the adjusting shaft 53, which has a diameter slightly smaller than the diameter of the press-fit seat 57. In this case, in order to adjust the precise rotation position of the driving pin, that is, the eccentric position of the driving pin, and thus the stroke starting position of the annular slider 17,
The first mark 67 is arranged at the joining position, that is, at the starting end of the sliding seat 61. The first mark 67 is the adjustment shaft 5
The second mark 68 of No. 3 is aligned so as to provide a correspondence between the eccentric position of the entrainment pin 45 and the position of the annular slider (for example, the mark horizontal corresponds to half of the eccentric stroke). As a result, the position of the annular slider required for uniform fuel delivery initiation of each pump piston 7 is individually adjustable via the pivoted position of the entrainment pin 45 in relation to the first starting element. is there. In this case, the drive pin is slidably guided in the bore 51 by the sliding seat 61 during the adjusting process. The mounting form of the entrainment pin 45 in the hole 51 of the adjusting shaft 53 is shown in FIGS. 3 to 6. In FIG. 3, the entrainment pin 45 is introduced into the hole 51. In this case, the maximum radial distance of the eccentric head 47 to the axis of the cylindrical portion 49 and the neck 65 to the axis is
The maximum distance is set to be smaller than the diameter of the hole 51 so that the entrainment pin can be easily inserted without tilting. In FIG. 4, the entrainment pin 45 reaches the hole 51 at the chamfer 59, in which case the length of the hole 51 is shorter than the maximum distance between the chamfer 59 and the head 47. . Further, as shown in FIG. 5, the sliding seat 61 is subsequently inserted into the hole 51. At this position, the rotational position of the carry pin 45 is adjusted, and in this case, the tool is used to move the end surface 55 of the carry pin 45 opposite to the head 47 side.
Engages in the shape connecting surface 73. In this case, the shape-connecting surface 73 can be formed either on the end surface 55 or on the outer peripheral surface of the entraining pin 45 as a molding portion. FIG. 6 shows the position of the entrainment pin 45 pushed into the hole 51. After the rotation position of the carry pin 45 is adjusted,
1 in position by an axial press fit. Further, the tightening of the entrainment pin 45 in the adjusting shaft 53 is performed by the press connection between the press-fit seat 57 and the hole 51. In this case, the driving pin 45 in the push-fitting process
The sliding seat 61 can be designed in the form of a cone for a positive guide of
A gradual transition to is guaranteed.

Therefore, according to the fuel injection pump of the present invention, unlike the known structural type, it is possible to make the fuel delivery timing uniform in all the pump elements with only two structural parts. This is the realization of full functionality,
This results in many advantages in terms of fabrication and assembly costs.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a part of a known fuel injection pump.

FIG. 2 is an enlarged view of a driving pin in the adjustment shaft.

FIG. 3 is a diagram showing a first stage of assembling a driving pin into a hole of an adjustment shaft.

FIG. 4 is a diagram showing a second stage of assembling the driving pin into the hole of the adjustment shaft.

FIG. 5 is a view showing a third stage of assembling the entrainment pin into the hole of the adjustment shaft.

FIG. 6 is a view showing a driving pin assembled in a hole of an adjustment shaft.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pump casing 3 Cylinder bush 5 Cylinder hole 7 Pump piston 9 End surface 11 Pump working chamber 13 Notch 15 Low pressure chamber 17 Annular slider 19 Web 21 Inner wall 23 Vertical groove 25 End face edge 27 Control hole 29 Inclined groove 31 Bottom surface 33 Control edge 35 Horizontal Hole 37 Blind hole 39 Passage 43 Notch 45 Carrying pin 47 Head 49 Seat 51 Hole 53 Adjusting shaft 55 End face 57 Press fit seat 59 Chamfering part 61 Sliding seat 63 Shaft part 65 Neck part 67, 68 Mark 69 End face 71 steps Attached hole 73 Shape connection surface

Continued front page (72) Inventor Reiner Hebeler Bretten Eichenstraße 32 Germany Bergheimer Wake 25

Claims (12)

[Claims] 1. A fuel injection pump for an internal combustion engine, which is guided in a cylinder hole (5) of a cylinder bush (3) and axially reciprocates by a cam drive mechanism and is pumped at one end face (9). At least one pump piston (7) that limits the working chamber (11) and is axially slidable on the pump piston (7) and extends within the pump piston into the pump working chamber (11). At least one connected and open to the outer circumference of the pump piston (7)
Annular slider (1) controlling two control ports (29)
7) and an adjusting shaft (53) which is mounted transversely to the axis of the pump piston in the pump casing (1) for simultaneously operating a plurality of annular sliders (17), Entrainment pins (45) are arranged on the adjusting shaft for changing the stroke position of the annular slider (17) in relation to the adjusting shaft (53), and each of the entraining pins axially moves the annular slider. Eccentrically arranged in a cylindrical portion (49) which engages in a notch (43) in each annular slider (17) for manipulating and is guided by a hole (51) in an adjusting shaft (53). And an annular slider (1
7) spherical head (4) engaging in notch (43)
7) with a cylindrical portion (4
Fuel injection pump for internal combustion engines, characterized in that 9) is fixed in the pivoted position by being pushed into the hole (51). 2. Cylindrical portion (49) of the carrying pin (45).
Or the bore (51) of the adjusting shaft (53) has a first section with a sliding seat (61), the drive pin (45) being self-locking by the adjusting tool with little energy consumption and It can be installed in an adjusted position and has a second section which follows the first section in the axial direction, said second section having a hole () during axial sliding of the entrainment pin (45). Fuel injection pump according to claim 1, characterized in that it cooperates with 51) to form a press-fit seat (57). 3. The adjusting shaft (53) and the entrainment pin (45) have marks (68, 67), with which the pivotal position of the entrainment pin (45) and the annular slider (1).
The fuel injection pump according to claim 2, wherein the stroke position of 7) is related. 4. A spherical head (47) is configured as a sphere segment, said head having an annular slider (17).
2. The fuel injection pump according to claim 1, characterized in that the side end surface (69) is flat, in which case the flat surface extends at right angles to the eccentric pin axis. 5. A spherical head (47) is provided with a shank (63) arranged concentrically to the axis of the head and eccentrically to the axis of the cylindrical seat (49). And a follower pin (45) following this shaft via the neck (65) which has a reduced diameter relative to the cylindrical seat and is on the axis of the cylindrical seat.
2. The fuel injection pump according to claim 1, characterized in that it is connected to the part of the seat forming the cylindrical seat (49). 6. The diameter of the cylindrical part (49) is equal to or greater than twice the maximum radial distance of the head (47) from the axis of the cylindrical part (49). The fuel injection pump according to claim 1. 7. Neck (65) and shank (63) between the head (47) and the cylindrical part (49) of the carrying pin (45).
Has a reduced diameter than the cylindrical portion, and the length of the neck (65) and shank (63) meeting is equal to the adjustment shaft (5
3) is larger than the length of the hole (51) for receiving the second section, and is twice the maximum radial distance of the head (47) from the axis of the cylindrical part (49). 7. The fuel injection pump according to any one of claims 1 to 6, characterized in that it is larger than the diameter of the fuel injection pump. 8. A press-fit seat (5) in the adjusting shaft (53).
The hole (51) forming the step 7) is formed as a smaller diameter portion of the stepped hole (71), and the larger diameter portion of the stepped hole is continued to the annular slider (17) side. And its diameter is greater than twice the maximum radial distance of the head (47) from the axis of the cylindrical portion (49), which is twice the distance of the smaller diameter of the stepped hole (71). 8. Fuel injection pump according to claim 7, characterized in that it is larger than the portion (51). 9. The neck (6) up to a radial plane passing through the maximum distance of the outer peripheral surface of the head from the axis of the cylindrical part (49).
5) and the shank (63) meet, the total length is the stepped hole (7
Fuel injection pump according to claim 5 or 8, characterized in that it is smaller than the width of the adjusting shaft (53) in the range 1). 10. Fuel injection pump according to claim 5, characterized in that the neck (65) is transferred to the cylindrical part (49) by means of a chamfer (59). 11. The driving pin (45) has a shape-connecting surface (73) on the end face opposite to the head (47) side, through which the driving pin is shaped-connecting. 2. The fuel injection pump according to claim 1, wherein the fuel injection pump can be rotated and adjusted by a rotating tool that engages with. 12. Sliding seat (61) for the carrying pin (45)
Fuel injection pump according to one of the preceding claims, characterized in that the diameter of the part forming is expanding conically towards the area of the press-fit seat (57).