JPH0340235B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for adjusting the injection timing of a fuel injection pump for an internal combustion engine, particularly a diesel engine.

In a conventional in-line fuel injection pump for diesel engines, a barrel is housed within the pump housing, and a pump chamber with a spring-loaded discharge valve is provided within the barrel, with one end facing the pump chamber and the other end facing the engine. a plunger operatively connected to a cam driven by the plunger, and a control sleeve is fitted around the plunger so as to be slidable in the axial direction, and the control sleeve is constantly supplied with fuel by a feed pump. For example, the one placed in the fuel chamber of
No. (filed on March 29, 1978). In this known device, a control groove is provided on the control sleeve that is inclined with respect to the axis of the plunger, and one end opens into the pump chamber and the other end opens near the lower end surface of the control sleeve to form a control hole. A channel is provided in the plunger, and the fuel injection amount is adjusted by rotating the plunger around its axis to change the relative position of the control port with respect to the control groove, and rotatably supported in the housing. The rotation of the eccentric pin on the camshaft displaces the control sleeve in the axial direction of the plunger to adjust the injection timing. And this kind of fuel injection pump is
Naturally, each cylinder of a multi-cylinder engine is equipped with one for each cylinder, but due to manufacturing errors and assembly errors of each part during manufacturing, the fuel injection timing of the fuel injection pump for each cylinder is usually not uniform. Therefore, it is necessary to match the fuel injection timing of each pump as evenly as possible before installing it in the engine. To do this, the conventional method was to check the injection timing by actually flowing fuel through each injection pump in each cylinder, and if there was a discrepancy, remove the seal plug in the housing and insert a tool through the adjustment opening to adjust the control sleeve and plunger. After fine-tuning the axial position of the engine, the seal plug was reinstalled and fuel was allowed to flow to check the injection timing. Therefore, as the number of cylinders increases, the task of adjusting the injection timing becomes extremely troublesome, resulting in a problem that requires a great deal of effort and cost.

The present invention was created in view of the above circumstances, and
A barrel housed in the housing, a plunger slidably inserted in the barrel in the axial direction, a spring-loaded discharge valve mounted in the barrel, and one end surface of the discharge valve and the plunger. a pump chamber bounded within said barrel; a fuel chamber within the barrel formed around said plunger; a control sleeve slidably fitted outside said plunger within said fuel chamber; one end disposed within said pump chamber; An oil passage in the plunger that opens to the plunger, and an oil passage provided on one side of the outer circumferential surface of the plunger and the control sleeve at an angle with respect to the axis of the plunger in order to connect or block communication between the pump chamber and the fuel chamber via the oil passage. control groove,
A control hole provided on the other of the outer peripheral surface of the plunger and the control sleeve and cooperating with the control groove, an injection amount control member that rotates the control sleeve around the plunger axis, and a control shaft substantially perpendicular to the plunger axis. an injection timing control member disposed above the control sleeve and engaged with the control sleeve to adjust the relative position of the sleeve with respect to the plunger in the axial direction of the plunger to adjust the fuel injection timing, the injection timing control member is configured to be adjustable and fixed on the control shaft about the axis thereof, wherein the discharge valve is removed and a fuel outlet downstream of the discharge valve is connected to a source of pressurized air via an air manometer. to force pressurized air to the pump chamber, remove the seal plug that normally blocks the adjustment opening of the housing, and displace the control sleeve upward or downward via the injection timing control member. the air manometer detects the moment when the control groove is opened or closed by the control sleeve, and the injection control member is fixed on the control shaft at that position. The gist of this paper is the injection timing adjustment method.

Embodiments of the present invention will be specifically described below with reference to the accompanying drawings. First, an example of the structure of the fuel injection pump to be adjusted according to the present invention will be described. Reference numeral 10 is a housing of the fuel injection pump, 12 is a barrel fitted into the upper end of the housing, and 14 is removably inserted into the upper end of the housing.
16 is a pump chamber formed in the barrel 12, and 16 is a discharge valve holder 18 screwed to the upper end of the barrel.
a fuel discharge valve 22 that is preloaded by a spring 20 housed therein to close off the pump chamber 14; a discharge passage that is provided within the discharge valve holder 18 and communicates with a fuel injection nozzle via a fuel injection pipe (not shown); 24 is connected to the housing 1 via the barrel 12.
The plunger is slidably fitted in the plunger 0, and its upper end surface 24a faces the pump chamber 14, and its lower end 24b contacts the cam 30 via the tappet 24 and roller 28. 32 is a camshaft driven by an engine (not shown); 34
36 is a spring that constantly presses the tappet 26 against the cam 30 side, and 36 is a fuel chamber formed surrounding the plunger 24, to which fuel is constantly supplied by a feed pump (not shown) during engine operation. . 38 is a cylindrical fuel control sleeve fitted on the outer periphery of the plunger 24 in the fuel chamber 36 so that it can freely slide in the axial direction and rotate freely; 40 is fitted on the outer periphery of the plunger 24 on the outer periphery of the sleeve 38; 42 is an injection timing control shaft whose axis is included in a plane perpendicular to the axis of the plunger 24; 44 is a bolt or bolt on the control shaft 42; It is a movable injection timing control member that is coaxially fixed by tightening a screw 46, and has an arm 48 projecting from the control member and a spherical portion 5 at the tip thereof.
0 is dried in the guide groove 40. 52 is a gear provided on the outer circumferential surface of the control sleeve 38 on the opposite side from the guide groove 40 over approximately a semicircumference;
54 is a control rack that meshes with the gear 52; 56 has one end open to the pump chamber 14, and the other end communicates with a control groove 58 cut into the outer peripheral surface of the plunger that contacts the inner peripheral surface of the control sleeve 38; The control groove 58 is an oil passage in the plunger that
In this embodiment, the plunger has a λ (lambda) shape as a whole, including a portion inclined with respect to the plunger axis and a portion extending in the direction of the plunger axis.
A control hole 60 is radially bored on the control sleeve 38 and cooperates with the control groove 58.
Reference numeral 2 denotes a plunger guide fitted to the lower end portion of the plunger 24, which has a square cross section 6 at the lower end.
4 is fitted into the corresponding square part 24c on the plunger 24, and as a result, the plunger 24 can be freely displaced in the axial direction with respect to the barrel 12 and the plunger guide 62, but around the axis, the plunger guide 62 It is designed so that it cannot rotate relative to the other side. Further, as shown in FIG. 4, a projection 68 having an engagement groove 66 extending in the axial direction is provided on the outer peripheral portion of the upper end flange of the plunger guide 62. On the other hand, an adjustment member 72 having an eccentric pin 70 that fits into the engagement groove 66 is rotatably fitted on the wall surface corresponding to the protrusion 68 of the housing 10, and the adjustment member 72 is mounted on the outside of the housing 10. A lock nut 76 is screwed into a threaded portion 74 protruding from the top.

An outline of the operation of the injection pump described above will be explained below. First, when each member of the pump is in the illustrated position, the control hole 60 and the control groove 58 do not communicate with each other, and the lower end of the control groove 58 protrudes below the lower end surface of the control sleeve 38 and opens into the fuel chamber 36. Therefore, the pump chamber 14 and the fuel chamber 36 are in communication. Now, when the camshaft 32 is rotated from this state and the plunger 24 is pushed upward by the cam 30 via the roller 28, the lower end of the control groove 58 is closed by the control sleeve 38, and the control groove Since communication between the inclined portion and the control hole 60 is cut off, communication between the pump chamber 14 and the fuel chamber 36 is cut off. Therefore, the fuel in the pump chamber is pressurized by the rise of the plunger 24, and when the pressure exceeds a set value, the discharge valve 16 is opened and fuel is supplied from the discharge passage 22 to the injection nozzle of the engine. When the plunger 24 rises further and the inclined groove portion of the control groove 58 communicates with the control hole 60 of the control sleeve 38, the pump chamber 14 communicates with the fuel chamber 36 again, and fuel injection ends. Note that after that, the upper end of the axial portion of the control groove 58 is connected to the control sleeve 38.
It protrudes upward from the upper end surface of the fuel chamber 36 to directly communicate the pump chamber 14 and the fuel chamber 36, thereby reliably preventing two-stage injection. Next, the control rack 54 is moved in its axial direction, the control sleeve 38 is rotated about the axis of the plunger 24, and the relative position between the control hole 60 and the control groove 58 is changed, thereby controlling the fuel consumption. The amount of supply is increased or decreased. In addition, during normal operation after completing the injection timing adjustment work described later,
The control arm 4 rotates the control shaft 42 around its axis.
By displacing the control sleeve 38 in the axial direction of the plunger 24 via the control hole 60
The relative position of the control groove 58 in the cam lift direction changes, that is, the injection timing is adjusted. As is well known in the art, the control rack 54 and the control shaft 42 are controlled artificially by an engine control device (not shown in the figures) (in the case of a vehicle, an accelerator pedal, a governor, a timer, etc.). Or driven by an appropriate actuator.

Now, in the fuel injection pump as mentioned above,
After the manufacturing and assembly is completed, it is necessary to align the fuel injection timings of the injection pumps of the plurality of cylinders before installing it in an actual engine. According to the present invention, the injection timing is adjusted as follows.

(1) First, remove the discharge valve holder 18 and remove the discharge valve 1.
After removing 6 and spring 20, replace barrel 1 again.
2, and an air manometer 78 is connected to the open end of the discharge passage 22 by a fitting 80. The air manometer 78 is also connected to a suitable compressed air source 84 via a pressure reducing valve 82.

(2) On the other hand, remove the seal plug 88 screwed into the adjustment opening 86 formed in the wall portion of the housing 10 facing the injection timing control member 44 to open the opening.

(3) When the pressure reducing valve 82 is opened in the above state, the regulated compressed air passes through the air manometer 78, passes through the discharge passage 22, the pump chamber 14, the oil passage 56, and the control groove 58.
The fuel flows into the fuel chamber 36 through the fuel chamber 36, and further flows out into the outside air. (At this time, the control sleeve 38 is assumed to be in the position shown in FIGS. 1 and 3.)
In this case, the mark 90 of the air manometer 78 is
Due to the airflow, it is in a floating position as shown.

(4) Then, by inserting a suitable tool through the adjustment opening 86 and slightly rotating the arm 48 of the injection regulation control member 44 clockwise in FIGS. 1 and 3, the plunger 24 In contrast, the control sleeve 38 moves downwards. control sleeve 38
At the moment when it descends and covers the lower edge of the control groove 58,
The flow of compressed air is stopped. This stoppage of the air flow can be accurately confirmed by the falling of the indicator 90 of the air manometer 78. This position is nothing but the injection start position.
The bolt or screw 46 is then tightened at this location to secure the control member 44 onto the control shaft 42.

Therefore, the injection timing of the injection pump for each cylinder can be adjusted very easily and quickly with respect to the appropriately set crank angle position (the axial position of the cam 30 and therefore the plunger 24). Comparing this to the case where, after checking this by flowing fuel as in the past, removing the seal and plug 88, making fine adjustments to the injection timing control member 44, and repeating the process several times by flowing fuel again, It is clear that the adjustment time is reduced by a factor of less and the costs are correspondingly reduced. Note that, contrary to the above method, the control groove 58 is first closed by the control sleeve 38,
Gradually raise the control sleeve 38, and confirm the moment when the lower end of the control groove 58 is opened by the lower edge of the sleeve and compressed air begins to flow, by the rise of the indicator 90 of the air manometer 78. You can also do it. Furthermore, in the above embodiment, the control groove 58 is provided on the plunger 24 and the cooperating control hole 60 is provided on the control sleeve 38; The present invention can be similarly applied to a device in which a control groove is provided that is inclined to the plunger 24, and a control hole that communicates with the oil passage 56 is opened in the outer peripheral surface of the plunger 24. Furthermore, although not directly related to the present invention, when aligning and matching the fuel injection amounts of the injection pumps of multiple cylinders, the lock nut 76 is loosened and the adjustment member 72 is rotated using a tool such as a screwdriver. . Then, due to the cooperation between the eccentric pin 70 and the engagement groove 66, the plunger guide 62 is rotated around the axis together with the plunger 24, and the control sleeve 3 of the plunger is rotated.
8 is changed, in other words, the relative position of the control hole 60 with respect to the control groove 58 is changed, so that the injection amount of the fuel injection pump corresponding to each cylinder is finely adjusted.

After completing the adjustment of the injection timing as described above, the seal plug 88 is screwed together, the air manometer 78 is removed, the discharge valve 16 and the spring 20 are set again, and the discharge valve holder 18 is placed in the normal position. By fixing the plunger 24 and tightening the lock nut 76 to prevent rotation about the axis of the plunger 24,
All work is completed.

As described above, the injection timing adjustment method for a fuel injection pump according to the present invention includes a barrel housed in a housing, a plunger fitted in the barrel so as to be slidable in the axial direction, and a plunger fitted in the barrel. a suspended spring-loaded discharge valve; a pump chamber defined within the barrel by the discharge valve and one end surface of the plunger; a fuel chamber within the barrel formed around the plunger; a control sleeve slidably fitted on the outside of the plunger; an oil passage in the plunger having one end open to the pump chamber; a control sleeve for communicating or blocking the pump chamber and the fuel chamber via the oil passage; A control groove provided on one of the outer circumferential surface of the plunger and the control sleeve at an angle with respect to the plunger axis; a control hole provided on the other of the outer circumferential surface of the plunger and the control sleeve and cooperating with the control groove; an injection amount control member that is rotated around the plunger, and is arranged on a control shaft substantially orthogonal to the plunger axis and engages with the control sleeve to adjust the relative displacement of the sleeve with respect to the plunger in the plunger axis direction. The fuel injection timing control member is configured to be fixed on the control shaft so as to be adjustable around the axis thereof, and the injection timing control member is configured to adjust the fuel injection timing. The valve is removed, and the fuel outlet downstream of the discharge valve is connected to a pressurized air source via an air manometer to forcefully send pressurized air to the pump chamber, and the adjustment opening in the housing is normally closed. removing the seal plug, displacing the control sleeve upward or downward via the injection timing control member, detecting with the air manometer the moment when the control groove is opened or closed by the control sleeve; The invention is characterized by fixing the injection control member on its control shaft at a fixed position, and is extremely useful because the injection timing of the fuel injection pump for multiple cylinders of the engine can be quickly, easily, and reliably fine-adjusted and aligned. be.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the entire pump showing an embodiment of the method of the present invention, Fig. 2 is a sectional view of the main part taken along the - line in Fig. 1, and Fig. 3 is a side sectional view of Fig. 2. , FIG. 4 is an exploded perspective view showing the injection amount adjusting portion of the pump shown in FIG. 1. 10...housing, 12...barrel, 14...
... Pump chamber, 16 ... Discharge valve, 24 ... Plunger, 30 ... Cam, 36 ... Fuel chamber, 38 ... Control sleeve, 42 ... Control shaft, 44 ... Injection timing control member, 54 ... Control Lack, 58...
... Control groove, 60 ... Control hole, 78 ... Air manometer, 82 ... Pressure reducing valve, 84 ... Compressed air valve, 8
8...Seal plug.

Claims (1)

[Claims] 1. A barrel housed in a housing, a plunger slidably inserted in the barrel in the axial direction, a spring-loaded discharge valve mounted in the barrel, and one end surface of the discharge valve and the plunger. a pump chamber bounded within said barrel by a fuel chamber defined within said barrel surrounding said plunger; a control sleeve slidably fitted outside said plunger within said fuel chamber; An oil passage in the plunger that opens into the chamber, and an oil passage provided on one side of the outer circumferential surface of the plunger and the control sleeve at an angle with respect to the axis of the plunger in order to connect or block communication between the pump chamber and the fuel chamber via the oil passage. a control groove provided on the other of the outer peripheral surface of the plunger and the control sleeve and cooperating with the control groove; an injection amount control member for rotating the control sleeve around the axis of the plunger; An injection timing control member is provided on orthogonal control shafts and engages with the control sleeve to adjust the relative position of the sleeve with respect to the plunger in the axial direction of the plunger, thereby adjusting the fuel injection timing. In the case where the injection timing control member is configured to be fixed on the control shaft so as to be adjustable about the axis thereof, the discharge valve is removed and the fuel delivery port downstream of the discharge valve is connected via an air manometer. While connecting to a pressurized air source and pumping pressurized air to the pump chamber, remove the seal plug that normally blocks the adjustment opening of the housing, and move the control sleeve upward through the injection timing control member. Alternatively, the air manometer detects the moment when the control groove is opened or closed by the control sleeve, and the injection control member is fixed on the control shaft at that position. How to adjust the injection timing of a fuel injection pump.