JPH0315821Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a fuel injection cam for an engine in which a cam nose chip is made of a material with excellent impact resistance and then fixed on the circumferential surface of a cam body.

<Prior art> There is a technology in which a small cam nose chip is fixed to the circumferential surface of the cam body, and the cam nose of this cam nose chip drives the fuel injection pump at high speed in a short period of time to increase the fuel injection pressure and improve combustion performance. With this technology, the cam nose is made of a strong material with excellent impact and wear resistance so that it can withstand large impact forces.

Conventionally, as shown in FIG. 10, the cam nose tip 3 was formed into a semi-cylindrical shape, fitted into a fitting groove 13 on the circumferential surface of the cam body 4, and fixed by brazing 14.

In addition, the present inventor considered what is shown in FIGS. 11 and 12 prior to the invention. That is, a clamp claw receiving surface 5, a tip lower surface receiving surface 6, and a tip back surface receiving surface 7 are formed on the circumferential surface of the cam body 4 in order from the upper side in the rotational direction, and the tip lower surface 8 of the cam nose tip 3 is formed.
to the lower face seat 6 of the chip, the back face 9 of the chip to the back face 7 of the chip, and the clamp claw 10 with the clamp bolt 11 between the clamp claw receiving face 5 and the cam nose chip 3.
The cam nose tip 3 is clamped and fixed between the clamp claw 10 and the tip rear receiving surface 7 by pressing the tip across the front side 12 of the tip.

<Problem that the invention attempts to solve> The conventional example shown in FIG. 10 has the following problems.

Since the cam nose chip 3 is heated during brazing, there is a risk that it will be annealed and its strength will decrease.

B Roasting is time consuming and has poor productivity, and
Replacing the cam nose tip is also difficult.

In the prior art example shown in FIGS. 11 and 12, the disadvantages (I) and (B) of the conventional example described above can be solved, but there are the following problems.

C. There is a risk that the cam nose tip 3 may fall off upward, left and right, and laterally outward.

D. Any one of the contact surfaces between the clamp claw receiving surface 5 and the clamp claw 10, the contact surface between the clamp claw 10 and the chip front surface 12, and the contact between the chip rear surface 9 and the chip rear surface receiving surface 7 is Since the cam nose tip contacts only at either the left or right end, the clamp is insufficient and the cam nose tip is likely to fall off.

The purpose of the present invention is to eliminate the decrease in strength and productivity of the cam nose chip due to brazing, and also to eliminate the possibility of the cam nose chip falling off.

<Industrial Application Field> In order to achieve the above object, the present invention provides clamp claws on the circumferential surface of the cam body 4 in order from the upper side in the direction of rotation, as shown in FIGS. 1 to 9, for example. Receptacle surface 5, lower chip receptacle 6 and rear chip receptacle 7
The cam lower surface 8 of the cam nose tip 3 is brought into contact with the tip lower surface receiving seat 6, the tip rear surface 9 is brought into contact with the tip rear receiving surface 7, and the clamp claw 10 is connected with the clamp claw receiving surface 5 and the tip of the cam nose tip 3 with the clamp bolt 11. The cam nose chip 3 is clamped and fixed between the clamp claw 10 and the chip rear receiving surface 7 by pressing across the front surface 12, so that the chip rear surface 9 and the chip front surface 12 are tapered downward toward each other. It is characterized in that the abutting surfaces between the chip back surface receiving surface 7 and the chip back surface 9 are formed into arcuate surfaces curved in the width direction.

<Function> In the present invention, as the clamp bolt 11 is tightened, the cam nose tip 3 is pushed by the clamp claw 10 and automatically rotates along the arc contact surface between the tip back surface 9 and the tip back surface receiving surface 7. The contact surface between the clamp claw receiving surface 5 and the clamp claw 10, the contact surface between the clamp claw 10 and the cam front surface 12, and the contact surface between the chip rear surface 9 and the chip rear surface receiving surface 7 are all on the entire surface along the left and right width direction. The cam nose tip 3 is strongly fixed by abutting it.

The fixed cam nose tip 3 has a tapered shape that widens downward, so it does not slip out upward.
Due to the circular arc fitting on the back surface 9 of the chip, it will not slip out to the left or right, so there is no risk of it falling off.

<Embodiments> Main Embodiment (See FIGS. 1 to 4) Hereinafter, embodiments of the present invention will be described based on the drawings.

Figure 4 shows the drive system for the fuel injection pump of a water-cooled vertical series multi-cylinder diesel engine.
The cam nose 16 of the cam nose tip 3 of the fuel injection cam 2 of 5 causes the cam roller 17 and the tappet 1
8. The plunger 23 of the fuel injection pump 1 part of the unit injector 22 is connected to the plunger 23 of the fuel injection pump 1 part of the unit injector 22 via the transmission mechanism 21 consisting of the push rod 19 and the rocker arm 20.
is driven, and the fuel in the plunger chamber 24 is injected into the combustion chamber 27 from the injection nozzle 26 of the injector 25.

1 to 3 show a fuel injection cam 2 including a cam body 4, a cam nose tip 3, and a clamp claw 10.
and a clamp bolt 11.

On the circumferential surface 4 of the cam body, a clamp claw receiving surface 5, a tip lower surface receiving surface 6, and a tip back surface receiving surface 7 are formed in order from the upper side in the rotation direction. The clamp pawl receiving surface 5 is formed in a groove shape at the center of the width of the circumferential surface of the cam body 4, and clamp pawl guide walls 2 are formed on both sides of the groove.
form 8. A screw hole 29 is formed in the center of the clamp claw receiving surface 5.

The cam nose tip 3 is made of a material with excellent impact resistance, and the lower surface 8 of the tip is connected to the lower surface receiving seat 6 of the tip.
Then, the chip back surface 9 is brought into contact with the chip back surface receiving surface 7.

By passing the clamp bolt 11 through the insertion hole 30 at the center of the clamp claw 10 and tightening it into the screw hole 29, the center part of the clamp claw 10 is pressed, and the clamp claw 10 is inserted between the clamp claw receiving surface 5 and the front surface of the cam nose tip 3. 12 to clamp and fix the cam nose chip 3 between the clamp claw 10 and the chip rear receiving surface 7. The upper surface of the clamp claw 10 is formed into a circular arc shape that substantially matches the circumferential surface of the cam body 4.

A chip back surface 9 and a chip front surface 12 are formed in a tapered shape that widens downward from each other. The abutting surfaces between the chip back surface receiving surface 7 and the chip back surface 9 are formed into arcuate surfaces curved in the width direction. This abutting arcuate surface is formed into a partially conical or partially cylindrical surface that is convex on the chip rear surface 9 side.

Note that a tip rear side portion 32 at the end of the cam nose 16 of the cam nose tip 3 on the lower side in the rotational direction than the nose top 31 is extended to a position beyond a point 34 where the cam roller 17 is struck by bouncing after passing the nose top 31. The above bouncing refers to the cam nose tip 3.
When the plunger 23 is instantaneously driven, the fuel in the transmission mechanism 21 and the plunger chamber 24 is elastically deformed, and this refers to the restoring repulsive force of this elastic deformation. With this structure, the impact force of the cam roller 17 due to bouncing is received by the tip rear side portion 32 made of a material with excellent impact resistance, thereby preventing dents from occurring.

Further, the height of the tip rear side portion 32 is set lower than the height of the nose top by a height h for preventing secondary injection. If the height of the rear tip portion 32 is the same as the height of the nose top 31, as shown in FIG.
When the tip is struck against the tip rear portion 32, the plunger 23 is pushed by the elastic restoring force of the transmission mechanism 21, and secondary injection from the injection nozzle 26 may occur. In the above structure, this secondary injection can be eliminated.

Other Embodiments As various other embodiments of the present invention, some of the main embodiments described above may be modified as follows.

A As shown in FIGS. 5 and 6, the clamp pawl receiving surface 5 is formed over the entire width of the circumferential surface of the cam body 4, and the clamp pawl 1 is
0 is positioned using a pair of positioning pins 33.

B As shown in FIG. 7, the clamp claw 10 is formed into a flat plate shape.

C. As shown in FIG. 8, the height of the rear part 32 of the tip is the same as the height of the nose top 31.

D As shown in FIG. 9, the circular arc surface on which the chip back surface 9 and the chip back receiving surface 7 come into contact is formed into a partially conical surface or a partially cylindrical surface with a concave side on the chip back surface 7 side.

<Effects of the invention> The present invention is constructed and operates as described below, and thus has the following effects.

(a) Since the cam nose tip is fixed by tightening the clamp bolt, there is no need for brazing, and there is no risk of the cam nose tip being annealed by the heat during brazing and causing a decrease in strength.

(b) It eliminates the need for time-consuming brazing, increases productivity, and allows easy replacement of the cam nose tip after it wears out by operating the clamp bolt.

C. The cam nose tip freely rotates along the arc contact surface on the back of the tip, and the contact surfaces of the cam nose tip and clamp claw automatically come into full surface contact along the left and right width directions, making it possible to firmly fix the cam nose tip. can.

D. The fixed cam nose tip is prevented from being pulled out upwards due to its downwardly expanding shape, and is also prevented from being pulled out to the left or right due to the circular fitting on the back of the tip, so there is no risk of it falling off.

[Brief explanation of the drawing]

1 to 3 show the main embodiment of the present invention,
Fig. 1 is an exploded perspective view, Fig. 2 is a cross-sectional view perpendicular to the axis after assembly, Fig. 3 is a plan view of Fig. 2, and Fig. 4 is a drive of the fuel injection pump of an engine according to an example of use of the present invention. FIG. 3 is a longitudinal side view of the device. 5 to 9 show various other embodiments of the present invention, FIG. 5 is an exploded perspective view, FIG. 6 is an axially perpendicular center cross-sectional view of the main parts of FIG. 5 after assembly, and FIG. 7 is an exploded perspective view of the present invention. - Fig. 8 is an axis-perpendicular center sectional view of the main part, and Fig. 9 is a plan view of the main part. FIG. 10 is a side view of the main part of the conventional example, FIG. 11 is a partially cutaway side view of the previous example, and FIG. 12 is a plan view of FIG. 11. 1...Fuel injection pump, 2...Fuel injection cam, 3...
Cam nose tip, 4...Cam body, 5...Clamp claw receiving surface, 6...Tip lower surface receiving surface, 7...Tip rear receiving surface, 8...Tip lower surface, 9...Tip back surface, 10...Clamp claw, 11...Clamp bolt, 12... Front of chip.

Claims (1)

[Scope of Claim for Utility Model Registration] The cam nose tip 3 of the fuel injection cam 2 that drives the fuel injection pump 1 of the engine is made of a material with excellent impact resistance, and the cam nose tip 3 protrudes above the surface of the cam body 4. In a fuel injection cam for an engine that is fixed and released, a clamp claw receiving surface 5, a tip lower surface receiving surface 6, and a tip rear surface receiving surface 7 are formed on the circumferential surface of the cam body 4 in order from the upper side in the direction of rotation. , cam nose tip 3
The bottom surface 8 of the chip is brought into contact with the bottom surface receiving seat 6 of the chip, the back surface 9 of the chip is brought into contact with the back surface 7 of the chip, and the clamp claw 1 is pressed.
0 with the clamp bolt 11 across the clamp pawl receiving surface 5 and the tip front surface 12 of the cam nose tip 3, and press the cam nose tip 3 against the clamp pawl 1.
0 and the chip rear receiving surface 7, and the chip rear surface 9 and the chip front surface 12 are formed into a tapered shape that widens downward from each other, and the chip rear receiving surface 7 and the chip rear surface 9 are brought into contact. A fuel injection cam for an engine characterized by having a width formed into an arcuate surface curved in the width direction.