JPS62284954A - Fuel injection pump - Google Patents

Abstract

PURPOSE:To secure smooth actuation of a piston all the time, by constituting it to support a spring seat free of rocking motion at the time of energizing the piston, being free of rotation and reciprocating motion, of a distributor type fuel injection pump in one direction by a spring. CONSTITUTION:A fuel injection pump 1 rotates a plunger 8 via a drive shaft to be interlocked with an engine, while it reciprocates this plunger 8 in the axial direction with action of a face cam 9 to be engaged with a cam roller. With this, after fuel drawn in a pump house 13 is pressurized, it is distributively fed to an injection nozzle via a distibuting port 16, a fuel passage 17, etc. In this case, when the plunger 8 is forcedly pressed toward the face cam 9 by dint of an engaging surface 8b of the plunger 8 is made so as to be pressed to the cam 9 via a spring seat 40 installing a convex spherical part 40c and a plate 42 installing a concave spherical part 42b receiving the spherical part 40c.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention Field of Industrial Application] The present invention relates to the structure of a fuel injection pump for a diesel engine, etc. This relates to the contact portion between the spring and the plunger.

[Prior Art] In an overflow type fuel injection pump that adjusts the amount of fuel injected by overflowing the fuel, the plunger moves at high speed as a piston due to the pressing force of the cam riding on the roller, and the fuel is delivered to each fuel injection valve. supplying.

The above-mentioned 1 langeer is a detachable member for the above-mentioned cam.
The plunger is engaged by an intervening mechanism and is given rotational force from the engine via the cam.The plunger is pressed in the direction of the cam by a spring and is maintained in engagement with the cam.
A piston movement is performed in conjunction with one gear movement of the cam.

By the way, there are various causes, for example, the cam and the plunger are eccentric, and the plunger is pressed against the inner wall of the cylinder in which it is fitted, causing the inconvenience of the plunger being stuck to the cylinder. was there.

Countermeasures against eccentricity between the cam and the plunger are as described in Japanese Utility Model Application No. 136857/1983.

[Problems to be Solved by the Invention] However, there is interference between the plunger and the spring seat, for example, when the spring is applying idle pressure to the plunger, or when the spring seat receiving the spring or the contact surface of the plunger If the flatness, smoothness, or parallelism with the back surface is poor, the plunger may interfere with the spring seat. As a result, the spring seat 1- presses the plunger in the rotational direction, and as a result, the problem still exists that the plunger sticks to the cylinder.

Therefore, the present invention employs the following configuration in order to solve the above problems.

Means for Solving Problem L] That is, the present invention changes the contact position of the roller with respect to the cam as the engine rotates, thereby causing the piston that moves in conjunction with the cam to resist the spring that urges the cam toward the cam. In a fuel injection pump that compresses fuel existing between the piston and a cylinder in which the piston fits and injects it into an engine.

The gist of the fuel injection pump is that the spring is configured to bias the piston via a contact surface curved with a predetermined curvature in at least one direction.

Here, among the contact surfaces curved with a predetermined curvature in at least one direction, the "surface curved with a predetermined curvature in one direction" means a cylindrical surface, and the contact surface is a convex A cylindrical surface is in contact with a concave cylindrical surface having the same curvature as the convex cylindrical surface, or it may be a surface that is curved in all directions. A convex spherical surface and a concave spherical surface having the same curvature can be used.

"Action" A spring biases the piston via a contact surface curved with a predetermined curvature in at least one direction. Therefore, even if the pressing force of the spring is uneven, sliding occurs on the contact surface, and the fluctuation in the pressing force is absorbed. Furthermore, even if the flatness, smoothness, or parallelism with the back surface of the contact surface or other parts on which the contact surface exists is low, the contact surface as a whole has a predetermined curvature in at least one direction as described above. Since it is curved, the pressing force of the spring caused by low flatness, smoothness, or low parallelism with the back surface is absorbed by the occurrence of sliding. This prevents the plunger from interfering with the spring seat, and no unnecessary force is applied to the cylinder.

Next, the present invention will be described in detail.The present invention is not limited to these, but includes various embodiments without departing from the gist thereof.

Embodiment] FIG. 1 shows a diagram of a fuel injection pump 1 according to a first embodiment of the present invention.
! indicates the abbreviation.

The fuel injection pump 1 is an electromagnetic spill metering fuel injection pump based on a Bosch type distribution fuel injection pump. The fuel injection pump 1 is driven by a drive shaft 2.
A vane type feed pump 3 is rotated in conjunction with an engine (not shown).

The vane type feed pump 3 introduces fuel in a fuel tank (not shown) from an inlet 4 through a filter, pressurizes this fuel to the pressure set by a regulator valve 5, and then pumps the fuel. The fuel is supplied to a fuel chamber 6 formed within the injection pump 1.

The drive shaft 2 drives a 1-langeer 8 and a face cam 9 via a coupling 7. This coupling 7 is 1
The plunger 8 and the face cam 9 are rotated integrally in the rotational direction, but the plunger 8 and the face cam 9 are allowed to freely move in the axial direction when the plunger 8 and the face cam 9 reciprocate in the axial direction. The face cam 9 is configured to rotate integrally with the face cam 9 by an engagement mechanism. For this engagement mechanism, a commonly known mechanism such as inserting two or more protrusions of the 7-lunger 8 into a hole of the face cam 9 can be used. Face cam 9 is fu.

The face cams 9 are pushed against the cam roller 11 by the spring 10 via the runger 8, and the face cams 9 are pushed against the cam roller 11 by sliding contact between the face cams 9 and the cam rollers 11.
When the cam crest rides on the cam roller 11, the plunger 8 interlocked with the face cam 9 is reciprocated. During one rotation, the plunger 8 is reciprocated a number of times (four times in this case) corresponding to the number of cylinders of the engine (not shown).

The plunger 8 is slidably and precisely fitted into a head 12 as a cylinder attached to the fuel injection pump 1, and the head 12 and the end face of the plunger 8 form a pump chamber 13.

Suction grooves 14 are formed on the peripheral surface of the end portion of the plunger 8, and one of these suction grooves 14 is formed during the suction stroke of the plunger 8, that is, when moving to the left in FIG. When communicating with a suction boat (not shown) provided in the head 12, fuel is sucked from the fuel chamber 6 into the pump chamber 13. Also 1
During the compression stroke of the langeer 8, that is, while moving to the right in FIG. 18, and is injected from B into the combustion chamber of the engine by an injection valve (not shown).

The pump chamber 13 has a solenoid valve spill type fuel metering mechanism (
A solenoid valve type) 20 is connected. That is, pump chamber 1
3 is communicated with the fuel M6 through overflow passages 21 and 22, and the overflow passage 21 is opened and closed by a solenoid valve 23.

The solenoid valve 23 is actuated by a solenoid 25, and when the solenoid 25 is energized, the needle valve 24 is activated and the pump chamber 13 is opened to the fuel chamber 6 via the overflow passage 21, 22. be done. Therefore, if the solenoid valve 23 is operated during the compression stroke of the plunger 8, the fuel pressurized in the pump chamber 3 will flow into the overflow passage 21.
．． 22 to the low pressure side fuel chamber 6, O2
The fuel is no longer sent to the injection passage 17 side, and the injection of fuel is stopped. This controls the amount of fuel injection to be supplied to the engine. Note that a part of the fuel that has overflowed into the fuel chamber 6 is returned to a fuel tank (not shown) via C.

The timing to start energizing the electromagnetic valve 23 is determined by an unillustrated electronic control circuit equipped with a microcomputer or the like.

The aforementioned cam roller 11 is held by a roller ring 27. This roller ring 27 is used for adjusting the fuel injection timing (
timer) 30. The fuel injection timing adjustment mechanism 30 includes a timer piston 31, and the fuel pressure in the fuel chamber 6 acts on one end surface of the timer piston 31. The fuel pressure in the fuel chamber 6 is equal to two parts of the engine rotational speed -
1, that is, it changes depending on the rotation speed of the feed pump 3. When the fuel pressure in the fuel chamber 6 acts on one end surface of the timer piston 31, the timer piston 31 is moved to the left in FIG. 1 against the force of the spring 32 acting on the pond surface. Such reciprocating motion of the timer piston 31 is transmitted to the roller ring 27 via the pin 33. 11th]
The timer piston 31 is shown in a posture perpendicular to the actual case, and in reality, the timer piston 31 is installed with its axis oriented in a direction perpendicular to the plane of the paper.

Therefore, the reciprocating movement of the timer piston 31 rotationally displaces the roller ring 27 about the drive shaft 2 . Therefore, the cam roller 11 and the eighth cam 9 are displaced relative to each other in the circumferential direction, so the timing at which the cam crest of the face cam 9 rides on the cam roller 11 is shifted, and the phase of the reciprocating motion of the plunger 8 with respect to the drive shaft 2 changes. . As a result, the communication timing between the distribution port 1-1 (J and the injection amount 2817) changes, so the fuel injection timing is automatically adjusted.

The roller ring 27 includes, for example, an electromagnetic pickup type,
A timing detector 35 such as a Hall element type or an optical angle detection type is attached, and a balsa 36 is fixed to the drive shaft 2. When one of the protrusions 37 formed on the pulser 36 crosses the timing detector 35 due to the rotation of the drive shaft 2, the timing detector 35
generates a signal. This signal is sent to the electronic control unit. When the electronic control device receives the output signal from the timing detector 35, it uses this signal as a reference signal and after a predetermined period of time, outputs a power signal to the solenoid valve 23 to command its operation.

When the roller ring 27 is rotated by the operation of the timer 30, the timing detector 35 is also rotated by the same phase as the roller ring 27. However, when the fuel injection timing is adjusted in -), the reference signal sent to the electronic control unit also shifts by the same phase, so the operating timing of the solenoid valve 23 changes,
Since the overflow timing also changes by the difference in the reciprocating timing of the plunger 8, the injection timing is not affected.

Next, the peripheral parts of the plunger 8 and face cam 9, which are the main parts of this embodiment, will be explained in detail with reference to FIGS. 2 and 3.

The spring 10 presses the first langeer 8 in the direction of the face cam 9 using the spring seat 40 and the plate 42.
The engaging portion 8a of the plunger 8 is connected to the face cam 9 through
This is done by pressing against.

As a result, the plunger 8 can interlock with the face cam 9 without the engagement portion 8a, which is merely inserted, being separated.

A sectional view of the spring seals 1 to 40 is shown in FIG. 3(A), a perspective view thereof is shown in FIG.
The spring seat 40 shown in FIG. A hole 40b is bored through which the plunger 8 passes. The hole 4
0b is an inner diameter larger than the outer diameter of the plunger 8, and while the spring seat 40 remains penetrated by the plunger 8, the spring seat 40 can be moved up to a certain angle.
The axis of the plunger 8 and the axis of the plunger 8 can intersect with each other. That is, the plate surface of the spring seat 40 is configured to form an angle other than a right angle with respect to the axis of the first langeer 8.

The peripheral edge of the hole 40b on the opposite side to the protruding direction of the protrusion 40a is raised to form a convex spherical portion 40c. The center of the spherical portion 40c is located on the axis of the spring seat 40.

On the other hand, the plate 42 has a disk shape, and a hole 42a through which the plunger 8 passes is bored in the center thereof.

The hole 42a has an inner diameter that is approximately the same as the outer diameter of the plunger 8, and the plate 42 is tightly fitted to the plunger 8.

The peripheral edge of the hole 42a is depressed and has a concave spherical surface 42b.
is formed. The center of the spherical portion 42b is the plate 42
Exists on the axis of The spherical surface portion 42b is a spherical surface having the same radius as the convex spherical surface portion 40C of the spring seat 40, and when both 40C and 42b are overlapped and pinned together, they come into close contact as shown in FIG.

Since the present embodiment is constructed as described above, even when the spring seat 40 is applied with a large pressing force by the spring seat 40, the spherical parts 40C and 42b slide against each other and the pressing force is applied to the spring seat 40. In other words, as shown in Fig. 1, if the pressing force of the spring 10 is high in the upper part of the figure, the spring seat 40 is placed in a uniform and balanced state. By rotating from the axis of the plunger 8, the pressing force of the spring 10 is balanced.In this way, the plate 42 receives a uniform pressing force from the spring seat 40 as a whole. Even if the spherical parts 40c and 42'b have low smoothness, and therefore the pressing force from the spring seat=10 to the plate 42 is biased, the bias can be absorbed by the sliding movement of the spherical parts 40c and 42'b. , the plate 42 receives a uniform pressing force as a whole from the spring seat 1-40.Furthermore, if the smoothness of the spring seat T-40 or other plate 1-42 is low, or if the spherical portion 40c , 42b or when the flatness of the surface of the pond or the parallelism with the back surface is low, a similar effect is produced.

In this way, the plunger 8 is not pushed away by the inner wall of the head 12, and the flat part of the plunger 8 does not occur.

Next, the main parts of the second embodiment will be explained in detail with reference to FIGS. 5 and 6. The other configurations are the same as in the first embodiment.

This embodiment differs from the first embodiment in that two springs 50 and 51 are provided, and in the shapes of the spring seat 52 and plate 54. both subrings 5
0.51 is passed through rods 45°iI6 installed in the housing 1a on both sides of the plunger 8, and presses the tin ring seat 52 on both sides of the plunger 8. The Suburi>
The push seat 52 presses the plunger 8 against the face cam 9 at the engaging portion 8a of the plunger 8 via the plate 54.

A cross-sectional view of the spring seat 52 is shown in FIG. 6(a).
The perspective view of the spring seat 52 is shown in (B), the cross-sectional view of the plate 54 is shown in FIG. 6 (C), and the perspective view is shown in (D). To,
Through holes 52a, 52b are bored, and the through holes 52a, 5
Projections 52c and 52d are erected in the axial direction along the entire circumference of the rod 2b, and the through holes 52a and 52b are for the rods 45+46 to pass through. A hole 52e through which the plunger 8 passes is bored in the center. The hole portion 52e is connected to the through holes 52a and 52b.
It has an elliptical shape with an inner diameter larger than the outer diameter of the plunger 8 in the direction. Therefore, while the spring seat 52 remains penetrated by the plunger 8, the through hole 52a,
52b and the axis of the plunger 8, and the axis of the spring seat 52 and the axis of the plunger 8 can intersect with each other up to a certain degree of angle. That is, like the spring seat 40 of the first embodiment, the plate surface of the spring seat 52 is made to form an angle other than a right angle with respect to the axis of the plunger 8.

Hole 5 on the opposite side to the protruding direction of the protrusions 52c and 52d
The peripheral edge portion 2c is raised to form a convex cylindrical surface portion 52f. The axis of the cylindrical surface portion 52f is perpendicular to the axis of the spring seat 52.

On the other hand, the plate 54 has a disk shape, and a hole 54a through which the first langeer 8 passes is bored in the center thereof.

The hole 54a has an inner diameter that is approximately the same as the outer diameter of the plunger 8, and the plate 54 is tightly fitted to the plunger 8.

The peripheral edge of the hole 54a is depressed, and the concave cylindrical surface 54
It forms b. The axis of the cylindrical surface portion 54b is connected to the plate 5.
It is perpendicular to the axis of 4. The cylindrical surface portion 54b is a cylindrical surface having the same radius as the convex cylindrical surface portion 52r of the spring seat 52, and when both 52f and 54b are overlapped,
In close contact.

Since this embodiment is constructed as described above, even when the springs 50, 51 apply different pressing forces to the spring seats 52, the cylindrical surface portions 52r, 54b
They are arranged so that they slide against each other and the pressing force is uniform and balanced. That is, in the second embodiment as well, if the pressing force of the spring 50 is higher than the pressing force of the spring 51, as shown in FIG. By rotating, the pressing force between both springs 50, 51 is balanced. In this way, the plate 54
In this case, a uniform pressing force is applied to the spring seat 52 as a whole. This point is "-foot opening cylinder surface part 52f
',, 5 = 1b has low smoothness, and even if the pressing force from the spring seat 52 to the plate 5.1 is different, the sliding of the cylindrical surface portions 52f and 54b will compensate for that 1 inch. As a result, the play 1-54 receives a uniform pressing force from the spring seat 52 as a whole. Furthermore, the same effect is produced in metals in which the surface of the spring seat 52 or the plate 54 has a low flatness, or in which the cylindrical surface portions 52f, 54b or the surface of the pond have low flatness or parallelism with the back surface. .

In this way, the present embodiment also produces effects similar to those of the first embodiment. The configuration of this embodiment includes two springs 50
．． 51 is used, so the solenoid valve 2 is used as in this embodiment.
It can also be carried out with a type of fuel injection pump that causes overflow due to spill ring instead of overflow due to No. 3.

The first embodiment was a combination of one spring and a spherical contact surface, and the second embodiment was a combination of two springs and a cylindrical contact surface. A combination with a shaped contact surface is equally effective.

Benyu Kuhadaza The fuel injection pump of the present invention is configured such that the spring biases the piston through a contact surface curved with a predetermined curvature in at least one direction, so that the spring does not exert biased pressure. Even if the contact surface between the plunger and the spring seat that receives the spring is not well flattened or smooth, or the parallelism with the back surface is poor, the spring seat I. As a result, the plunger does not stick to the cylinder, and smooth rotation can be realized.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a schematic configuration of a fuel injection pump according to a first embodiment of the present invention, FIG. 2 is a partially enlarged explanatory diagram thereof, and FIG. 3 (A)
is a vertical cross-sectional view of the spring seat of the first embodiment, and FIG.
B) is a perspective view thereof, FIG. 3(C) is a vertical sectional view of the plate of the first embodiment, FIG. 3(D) is a perspective view thereof, and FIG. 4 is an explanatory diagram of the operation of the first embodiment. Fig. 5 is a partially enlarged explanatory view of the second embodiment, Fig. 6 (a) is a vertical sectional view of the spring seat of the second embodiment, Fig. 6 (b) is a perspective view thereof, and Fig. 6 (c) 6(d) is a longitudinal sectional view of the plate of the second embodiment, and FIG. 6(d) is a perspective view thereof. 1... Fuel injection pump 8... Plunger 9... Face cam 10... Spring 40.52... Spring seat 42.54... Plate 40c ...Convex spherical surface part 42b...Concave spherical surface part 52f...Convex cylindrical surface part 54b...Concave cylindrical surface part

Claims (1)

[Claims] 1. By changing the contact position of the roller with respect to the cam with the rotation of the engine, the piston interlocked with the cam can be
A fuel injection pump that is moved against a spring biased toward a cam, compresses fuel existing between the piston and a cylinder in which the piston fits, and injects it into the engine. A fuel injection pump characterized in that the spring is configured to bias the piston via a contact surface curved with curvature. 2. The fuel injection pump according to claim 1, wherein the contact surface is a spherical surface.