JPH1182218A - Distributor type fuel injection pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deformation of a plunger in time of high pressure injection, from occurring. SOLUTION: This fuel injection pump is provided with a distributive port 21 on a peripheral surface of a plunger 20 and two balance ports 22 to be opened in communicating with this distributive part 21 and a high pressure feed chamber 12, at a position shifted to both circumferential sides from the opposite side at 180 deg. of the distributive port 21, respectively. When the distributive port 21 is turned to high pressure by fuel injection, these balance ports 22 generate such a force as nearly commensurable to the force of the plunger 20 receiving in the radial direction by dint of pressure in the distributive port 21, so that the plunger 20 will not cause any deformation in the radial direction at all. Accordingly, since any possible seizure between the plunger 20 and a cylinder 10 is preventable, a clearance between the plunger 20 and the cylinder is reduced and pressure in the fuel injection is improvable so better than the case where the balance port 22 is not installed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a distribution type fuel injection pump used for a fuel injection pump for an internal combustion engine, particularly a diesel engine.

[0002]

2. Description of the Related Art In recent years, demands for high-pressure injection for a fuel injection pump used for a diesel engine of an automobile or the like have been increased with the tightening of exhaust gas regulations. In a distributed fuel injection pump in which fuel is pumped by a plunger reciprocating in a cylinder and rotating at the same time, the plunger is housed in the cylinder through a certain clearance. As one of means for achieving high-pressure injection of the fuel injection pump, it is effective to reduce the clearance between the plunger and the cylinder.

[0003]

However, at the time of high-pressure injection, the plunger is slightly deformed in the radial direction by pressure from the distribution port provided in the plunger. In such a case, if the clearance between the plunger and the cylinder is too small, the oil film may be broken, and the plunger and the cylinder may come into contact with each other, causing seizure. When burn-in occurs, in the worst case, there is a problem that the plunger and the cylinder adhere to each other, making it impossible to inject fuel and stopping the engine. Therefore, there is a limit in increasing the injection pressure of the fuel injection pump by reducing the clearance between the plunger and the cylinder.

[0004] The present invention has been made to solve the above problems, and has as its object to provide a distribution type fuel injection pump capable of preventing deformation of a plunger during high pressure injection.

[0005]

According to the distribution type fuel injection pump of the present invention, the force generated by the fuel pressure from the opening position of the distribution port substantially balances the force received by the plunger in the radial direction. Since the balance port has a balance port that communicates with the high-pressure pumping chamber and opens to the outer peripheral surface of the plunger, the plunger does not deform in the radial direction even when the pressure of the distribution port increases during fuel injection. Therefore, seizure between the plunger and the cylinder can be prevented, so that the clearance between the plunger and the cylinder can be reduced and the pressure of fuel injection can be increased as compared with a case where the balance port is not provided.

According to the distribution type fuel injection pump according to the second aspect of the present invention, the distribution type fuel injection pump can communicate with the high pressure pumping chamber, and has a force substantially balanced with a force which the plunger receives in the radial direction by the fuel pressure from the opening position of the distribution port. It has a balance port that opens to the inner circumference of the cylinder to generate. By connecting the high pressure pumping chamber and the balance port when the pressure at the distribution port during fuel injection increases, the plunger does not deform in the radial direction even if the pressure at the distribution port increases. Can be prevented from burning. Therefore, it is possible to reduce the clearance between the plunger and the cylinder and increase the fuel injection pressure as compared with the case where the balance port is not provided.

According to the distribution type fuel injection pump of the third aspect of the present invention, a notch provided on the outer peripheral surface of the plunger at the end of the plunger on the side of the high-pressure pumping chamber, and a communication passage which can communicate the notch with the balance port. Therefore, the balance port and the high-pressure pumping chamber can be communicated with a simple structure.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention; (First Embodiment) FIG. 2 shows a distribution type fuel injection pump according to a first embodiment of the present invention. The plunger 20 which is reciprocally and rotatably accommodated in the cylinder 10 via a clearance is driven by a cam plate 50 connected to a drive shaft (not shown) by a coupling, and is pressed against the cam plate 50 by urging means (not shown). Have been. The cam plate 50 has the same number of face cams 51 as the number of cylinders of the engine, and when rotated by a drive shaft, reciprocates on a fixed roller 60 by a prescribed cam lift. Therefore, the plunger 20 connected to the cam plate 50 reciprocates at the same time as the plunger 20 rotates in the cylinder 10 and reciprocates, so that the plunger 20 moves to the high-pressure pumping chamber 12 formed between the one end face of the plunger 20 and the cylinder 10. The fuel is sucked, and the fuel is sequentially distributed and pressure-fed from a fuel intake port 26 of the plunger 20 to a plurality of distribution passages 13 provided in the cylinder 10 from a distribution port 21 opened on the outer peripheral surface of the plunger 20 through the inside of the plunger 20. . The fuel pressure-fed to the distribution passage 13 is injected from the injection nozzle 80 through the delivery valve 40. Fuel pumping is performed by the following steps (1) to (3).

(1) Suction stroke When the plunger 20 moves to the left in FIG. 2 and the suction groove 23 at the tip of the plunger 20 matches the suction port 11 opened on the inner peripheral surface of the cylinder 10, fuel is sucked. The gas is sucked from the groove 23 into the high-pressure pumping chamber 12, and further from the fuel inlet 26 into the plunger 20.

(2) Injection stroke As the plunger 20 rotates, the suction port 11 is closed, and is opened on the outer peripheral surface of the plunger 20 to open the high-pressure pumping chamber 12.
The distribution port 21 communicating with the distribution passage 13 is opened to one distribution passage 13. When the plunger 20 further rotates, the face cam 51 rides on the roller 60, and the plunger 20 starts to move rightward, and the fuel pumping starts.

(3) End of Injection When the plunger 20 is further moved rightward by the cam plate 50, the spill port 27 of the plunger 20 is opened to the pump chamber, and the inside of the plunger 20 and the high-pressure pumping chamber 1 are opened.
The high-pressure fuel of No. 3 is pushed back into the pump chamber from the spill port 27, the pressure drops, and the pumping of the fuel ends.

The fuel cut solenoid 30 is turned on and off by an ignition switch (not shown) to open or shut off the fuel passage 14 leading to the suction port 11 of the cylinder 10. When the ignition switch is set to the start position, the voltage is changed to the fuel cut solenoid 30.
, The valve in the fuel cut solenoid 30 pushes down the spring and is sucked upward, so that the fuel passage 1
Open 4. When the ignition switch is turned to the OFF position, the current flowing through the fuel cut solenoid 30 is cut off, the valve in the fuel cut solenoid 30 is pushed downward by a spring, the fuel passage 14 is cut off, and fuel is no longer injected into the cylinder 10. .

When the spill ring 70 is moved, the effective stroke (the plunger stroke from the start of fuel pumping to the end of pumping) changes. When the spill ring 70 moves to the left in FIG. 2, the effective stroke decreases, and the injection amount decreases. Conversely, when moving to the right, the effective stroke increases and the injection amount increases. In this embodiment, FIGS.
As shown in FIG. 3, a balance port 22 communicating with the high-pressure pressure chamber 12 is opened on the outer circumferential surface of the plunger 20 at a position opposite to the position where the distribution port 21 is opened in the circumferential direction. For example, when the engine is a four-cylinder engine, the distribution port 21 communicates with the distribution passage 13 if the balance port 22 is located at the same position in the axial direction as the distribution port 21 on the outer peripheral surface of the plunger 20 and 180 ° in the circumferential direction on the opposite side. Then, the balance port 22 communicates with another distribution passage 13 and pressurizes the fuel to the cylinder on the opposite side. In order to avoid this, 180 ° of distribution port 21
45 on both sides in the circumferential direction of the plunger 20 from the opposite side.
Two balance ports 22 are provided at shifted positions. The pressure in the high-pressure pumping chamber 12 acts on the inner wall surface of the cylinder 10 from the balance port 22. The area of the balance port 22 is set such that the force received by the plunger 20 in the radial direction by the pressure of the distribution port 21 and the resultant force of the force received by the plunger 20 in the radial direction by the pressure of the two balance ports 22 are substantially balanced.

With the above configuration, even if the pressure at the distribution port 21 increases during the fuel injection stroke, the force received by the plunger 20 in the radial direction due to the pressure at the distribution port 21 and the force due to the pressure at the balance port 22 are reduced. Are balanced and canceled, so that the plunger 20 can be prevented from being deformed. Therefore, even when the clearance between the plunger 20 and the cylinder 10 is reduced, the plunger 20 does not come into contact with the cylinder 10 due to deformation of the plunger 20 and seizure does not occur, so that higher-pressure fuel can be injected. Become.

In the first embodiment, the balance port 2
2 denotes a distribution port 21 on the outer peripheral surface of the plunger 20.
Although it was provided at two locations shifted 45 ° to both sides in the circumferential direction from the opposite side, the plunger 2
If the area of the balance port 22 is set so that 0 is balanced with the force received in the radial direction, the same effect can be obtained even if the angle to be shifted is another angle. It is also possible to provide three or more balance ports 22. If the engine has an odd number of cylinders, the balance port 22 may be provided 180 ° opposite the distribution port. In this case, the area of the balance port 22 is substantially the same as the area of the distribution port 21.

(Second Embodiment) FIGS. 4 and 5 show a second embodiment of the present invention. The substantially same parts as those in the first embodiment are denoted by the same reference numerals. In the second embodiment, a balance port 15 that can communicate with the high-pressure pressure chamber 12 is provided on the inner circumferential surface of the cylinder 10 on the opposite side in the circumferential direction, corresponding to each of the plurality of distribution passages 13 provided on the inner circumference of the cylinder 10. It is open.
The high-pressure pumping chamber 12 and the balance port 15 can communicate with each other by a notch 24 provided in the plunger 20 and a communication path 16 provided in the cylinder 10 when the distribution port 21 communicates with the distribution passage 13. The notch 24 is provided at a position that does not overlap with the suction groove 23. When the high-pressure pumping chamber 12 and the balance port 15 communicate with each other, the pressure in the high-pressure pumping chamber 13 acts on the outer peripheral surface of the plunger 20 from the balance port 15.

FIG. 5 shows the cylinder 10 and the plunger 20 when the number of cylinders of the engine is four in this embodiment.
FIG. 3 is a sectional view taken along line BB shown in FIG. When the distribution port 21 of the plunger 20 communicates with the distribution passage 131, the high pressure pumping chamber 12 and the two balance ports 151, 15 are formed by the two notches 241 and 242 and the two communication passages 161 and 162.
2. When the number of cylinders of the engine is an even number as in the present embodiment, for example, the cylinder 10
There is another distribution passage 133 on the inner peripheral surface of the distribution passage 131 on the opposite side of the distribution passage 131 by 180 ° in the circumferential direction, and a balance port cannot be provided. Two balance ports 15
1 and 152 correspond to one distribution passage 131.
When the number of cylinders of the engine is odd, a balance port may be provided on the inner peripheral surface of the cylinder 10 on the opposite side of the distribution passage by 180 ° in the circumferential direction.

The area of the two balance ports 151 and 152 is substantially equal to the sum of the force received by the plunger 20 in the radial direction by the pressure of the distribution port 21 and the force received by the plunger 20 in the radial direction by the pressure of the balance ports 151 and 152. It is set to balance. When the distribution port 21 communicates with the distribution passage 132, two notches 24
The high-pressure pumping chamber 12 communicates with the two balance ports 152 and 153 by the two communication passages 162 and 163. If the distribution port 21 is the distribution passage 133 or 134
The same applies to communication with

With the above configuration, the distribution port 21
Distribution port 2 during the injection stroke when the
1 increases, the force received by the plunger 20 in the radial direction due to the pressure of the distribution port 21 is reduced.
5, the plunger 20 can be prevented from being deformed. In the above-described second embodiment, the balance port 15 is provided at substantially the same position in the axial direction as the distribution passage 13 of the cylinder 10, but the balance port 15 is provided at a position corresponding to the leading or trailing end position of the plunger 20. However, since the radial component of the force received by the plunger 20 can be balanced,
This has the effect of preventing the plunger 20 from being deformed in the radial direction. In this embodiment, two balance ports 15 are provided in the cylinder 10, but only one balance port or three or more balance ports can be provided. Notch 24 and balance port 1
Even if the cutouts 5 are not provided separately, the notch 24 can also function as a balance port and balance the radial component of the force received by the plunger 20.

Third Embodiment FIG. 6 shows a plunger 20 and a distribution passage 13 according to a third embodiment of the present invention. The substantially same parts as those in the first embodiment are denoted by the same reference numerals. In this embodiment, the balance port 2 communicating with the high-pressure pumping chamber 12 is provided on the outer peripheral surface of the plunger 20 on the side opposite to the position where the distribution port 21 is located.
5 are provided. For example, when the engine is a four-cylinder engine, the balance port 25 communicates with the distribution passage 13 if the balance port 25 is located at the same position in the axial direction of the outer peripheral surface of the plunger 20 and 180 ° in the circumferential direction of the distribution port 21 on the opposite side. In the meantime, the balance port 25 communicates with another distribution passage 13 and pressurizes the fuel to the cylinder on the opposite side. In order to avoid this, the two balance ports 2 shifted to both axial sides of the plunger 20 so as not to communicate with another distribution passage 13
5 are provided. The pressure in the high-pressure pumping chamber 12 acts on the inner wall surface of the cylinder 10 from the balance port 25. The area of the balance port 25 is set so as to be substantially balanced with the force due to the pressure of the distribution port 21. Here, the area of each of the two balance ports 25 is about half of the area of each distribution port 21.

With the above configuration, even if the pressure of the distribution port 21 increases during the fuel injection stroke, the force received by the plunger 20 in the radial direction by the pressure of the distribution port 21 and the force by the pressure of the balance port 25 are reduced. Are balanced to prevent the plunger 20 from being deformed. Therefore, even if the clearance between the plunger 20 and the cylinder 10 is reduced, the plunger 20 and the cylinder 10 do not come into contact with each other due to radial deformation of the plunger 20, so that seizure does not occur.

In the third embodiment, the balance port 2
Reference numeral 5 denotes a distribution port on the outer peripheral surface of the plunger 20 and 1 in the circumferential direction.
The plunger 20 is provided at two positions at positions opposite to each other by an angle of 80 ° on both sides in the axial direction. However, the area of the balance port 25 is set such that the pressure of the distribution port 21 balances the force received by the plunger 20 in the radial direction. If so, three or more balance ports can be provided. It is also possible to shift the balance port in the circumferential direction of the plunger 20 as in the first embodiment, and to shift in the axial direction as in the third embodiment. Furthermore, even when only one balance port 25 is provided, which is displaced in the axial direction of the plunger 20, a radial force can be generated by the pressure of the distribution port that is substantially balanced with the force received by the plunger 20 in the radial direction. Therefore, there is an effect that the force that the plunger 20 receives in the radial direction is offset, and the deformation of the plunger 20 is prevented.

In the above embodiments, the case where the number of cylinders of the engine is four has been mainly described. However, the present invention has the same effect in engines having other cylinders. In the above embodiment, the fuel is sucked into the high-pressure pumping chamber by the suction groove provided in the plunger. However, the same effect can be obtained even when the intake of fuel into the high-pressure pumping chamber is controlled by opening and closing the solenoid valve. Having.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a plunger and a distribution port according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the distribution type fuel injection pump according to the first embodiment of the present invention.

FIG. 3 is a perspective view of the plunger according to the first embodiment of the present invention.
FIG. 3 is a sectional view taken along line A.

FIG. 4 is a sectional view of a distribution type fuel injection pump according to a second embodiment of the present invention.

5 is a sectional view of the cylinder and the plunger according to a second embodiment of the present invention, taken along line BB of FIG. 4;

FIG. 6 is a perspective view showing a plunger and a distribution port according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Cylinder 12 High-pressure pumping chamber 13 Distribution passage 15 Balance port 16 Communication passage 20 Plunger 21 Distribution port 22 Balance port 24 Notch 25 Balance port 26 Fuel inlet

Claims (3)

[Claims] 1. A plunger having a fuel inlet and a distribution port, and the plunger is reciprocally movable and rotatably housed therein.
A cylinder forming a high-pressure pumping chamber communicating with the fuel suction port and the distribution port between the plunger and the axial end surface thereof, wherein the fuel in the high-pressure pumping chamber pressurized by the reciprocating movement of the plunger is provided. A distribution type fuel injection pump for pumping from a distribution port, wherein said distribution type fuel injection pump communicates with said high pressure pumping chamber so as to generate a force substantially balanced with a force received by said plunger in a radial direction by a fuel pressure from an opening position of said distribution port. A distribution type fuel injection pump having a balance port opened on the outer peripheral surface of a plunger. 2. A plunger having a fuel inlet and a distribution port, and the plunger is housed reciprocally and rotatably,
A cylinder forming a high-pressure pumping chamber communicating with the fuel suction port and the distribution port between the plunger and the axial end surface thereof, wherein the fuel in the high-pressure pumping chamber pressurized by the reciprocating movement of the plunger is provided. A distribution type fuel injection pump for pumping from a distribution port, the pump being communicable with the high pressure pumping chamber, and generating a force substantially balanced with a force received in a radial direction by the plunger by a fuel pressure from an opening position of the distribution port. And a balance port opening on the inner peripheral surface of the cylinder. 3. A notch provided on an outer peripheral surface of an end of the plunger on the side of the high-pressure pumping chamber, and a communication path that allows the notch to communicate with the balance port. 3. The distribution type fuel injection pump according to item 1.