JPH034780Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a distribution type fuel injection pump used in diesel engines.

(Prior Art) A so-called bottle-type distribution fuel injection pump includes a feed pump provided on the rear side of the injection pump body, a cam chamber formed between the feed pump and the head portion of the injection pump body, and a cam chamber formed between the feed pump and the head portion of the injection pump body. The drive shaft and the plunger are connected by a cam so as to impart reciprocating rotational motion to the plunger.

Normally, the cam chamber is used as a fuel chamber, and the fuel discharged from the feed pump enters the cam chamber, and the entered fuel is also used to lubricate the cam etc. Due to its low viscosity and insufficient performance as a lubricating oil, there is a demand for the use of a special lubricating oil to lubricate cams, etc., especially when used at high loads and high speeds. Ta.

As a means to satisfy this requirement,
In Publication No. 154134, a solenoid valve is provided in the head of the injection pump body to control the amount of fuel overflowing from a pressure chamber surrounded by a cylinder and a plunger.
This solenoid valve replaces the governor and control sleeve of the cam chamber, and the outlet of the feed pump and the inlet of the solenoid valve are communicated via a communication path that bypasses the cam chamber, so that fuel does not flow into the cam chamber. It is disclosed that a dedicated lubrication is supplied by shutting off the lubrication.

(Problem to be solved by the invention) However, the above-mentioned publication does not disclose anything about the seal between the lubrication space including the cam chamber and the feed pump, and this seal is performed by an ordinary oil seal. The problem is that the pressure of the fuel pressurized by the feed pump is applied to the oil seal, and the fuel leaks from the oil seal into the lubrication space, diluting the lubricating oil in the lubrication space and reducing the performance of the lubricating oil. It was hot.

Therefore, the object of this invention is to provide a distribution type fuel injection pump that prevents the fuel from the feed pump from leaking into the lubrication space and is more durable.

(Means for Solving the Problems) The gist of this invention is that in a distributed fuel injection pump in which a feed pump is provided adjacent to a lubrication space to which lubricating oil is supplied, the lubrication space and the feed pump An oil seal installed around the drive shaft is used to seal the gap between the
The seal chamber in which the oil seal is disposed communicates with the low pressure side of the feed pump through a pressure relief passage.

(Function) Therefore, since the seal chamber and the low pressure side of the feed pump communicate through the pressure relief passage, the pressure of the fuel applied to the oil seal is released to the low pressure side of the feed pump, and the pressure in this seal chamber is released to the oil It is possible to limit the pressure to a value below which fuel leaks through the seal, and therefore the above object can be achieved.

(Example) Hereinafter, an example of this invention will be described with reference to the drawings.

In Figs. 1 and 2, the injection pump main body 1
The head part 1a is fixed to one end of the rear part 1b. A drive shaft insertion hole 2 is formed in the center of the rear portion 1b of the main body 1, and a drive shaft 3 is inserted into the drive shaft insertion hole 2. This drive shaft 3
is rotatably supported by plain bearings 4a and 4b on both sides of the drive shaft insertion hole 2, and one end of the drive shaft 2 protrudes from the rear portion 1b to receive the driving force from the engine. The other end of the drive shaft 3 extends into a cam chamber 5 formed within the main body 1.

On the other hand, a barrel 6 is inserted and fixed into the head portion 1a of the main body 1, a cylinder 7 is formed at the center of the barrel 6, and a plunger 8 is formed in the cylinder 7.
is slidably inserted therein, and the cylinder 7 and plunger 8 constitute a pressure chamber 9. One end of the plunger 8 is located in the cam chamber 5 and connected to one surface of a cam disk 11 via a pin 10. The cam disk 11 is connected to the end of the drive shaft 3 via a cross-shaped coupling 12 so as to allow axial movement.
Further, around this coupling ring 12, a roller holder 13 fixed to the rear portion 1b of the main body 1 is provided.
is located. A plurality of rollers (not shown) are rotatably supported by the roller holder 13, and a cam surface having alternating peaks and troughs in the circumferential direction is formed on the other surface of the cam disk 11, and the cam surface has the above-mentioned cam surfaces. The rollers make contact to form a cam.
The pressing force of a pressing spring 15 acts on one surface of the cam disk 11 via a spring receiver 14, and when the drive shaft 3 rotates, the plunger 8 rotates and the cam and pressing spring 15 are Collaboration has led to reciprocating movements.

The solenoid valve 15 has a solenoid valve main body 16 screwed to the upper part of the head portion 1a of the main body 1, and a lid body 1 fixed to the upper part of the solenoid valve main body 16 and the main body 16.
An armature 18 is disposed between the armature 7 and the armature 7.
Further, a stator 2 having an excitation coil 19 is disposed in the solenoid valve body 16 opposite to the armature 18.
0 is fixed. Further, a valve stem 21 extends downward from the center of the lower surface of the armature 18, and the tip of the valve stem 21 is connected to a valve seat 2 formed in the electromagnetic valve body 16.
I am seated at number 2. Further, a return spring 23 is interposed between the electromagnetic valve body 16 and the valve stem 21, and when the excitation coil 19 is excited, the return spring 23
The tip of the valve stem 21 seats on the valve seat 22 against the
An inlet 24 and an outlet 25 formed in the solenoid valve body 16
When the excitation coil 19 is demagnetized, the return spring 23 causes the tip of the valve stem 21 to return to the valve seat 2.
2, and communicates the inlet 24 with the outlet 25.

An outlet 25 of the electromagnetic valve 16 communicates with the pressure chamber 9 via a fuel intake passage 26 formed in the head portion 1a of the main body 1 and the barrel 6. Further, a vertical hole 28 whose one end opens into the pressure chamber 9 is formed at the axial center of the plunger 8, and the other end of this vertical hole 28 opens into the discharge group 2, which is also formed in the plunger 8.
Connected to 9. Around this discharge group 29, a number of distribution holes (not shown) corresponding to the number of cylinders are formed in the head portion 1a of the main body 1, and these distribution holes are connected to a delivery section 30 having a delivery valve. .

Connectors 31a and 31b are screwed to the head portion 1a and rear portion 1b of the main body 1, respectively. The head-side connector 31a is connected to the inlet 24 of the solenoid valve 16 via a communication path 32 formed in the head portion 1a of the main body 1, and a connecting pipe 3 provided on the outside of the main body 1.
3 to the rear side connector 31b,
The rear connector 31b is connected to a fuel outlet 43 of a feed pump 34, which will be described below.

The feed pump 34 is provided adjacent to the cam chamber 5 in the main body 1, and as shown in FIG.
The rotor itself is of a well-known vane type and has a circular rotor 35.
The rotor 35 has a keyway 36 formed in each of the rotor 35 and the drive shaft 3.
It is fixed to the drive shaft 3 via a key 37 that fits into the keys 36a and 36b. Vane grooves 38 are formed, for example, every 90 degrees in the radial direction of the rotor 35, and vanes 39 are slidably inserted into each of the vane grooves 38. Further, a circular guide ring 40 is provided around the rotor 35 eccentrically from the rotor 35, and the tips of the vanes 39 are guided by the inner surface of the guide ring 40, and the vanes 39
rotates, and the volume of the working chamber 41 surrounded by the rotor 35, vane 39, and guide ring 40 changes as the rotor 35 rotates, sucks fuel from the fuel inlet 42 formed in the rear part 1b, and pressurizes it. Similarly, the fuel is discharged from a fuel outlet 43 formed in the rear portion 1b.

The guide ring 40 connects the rear portion 1b and the cover 4.
It is sandwiched between 4 and 4. This cover 44 is
An insertion hole 45 is formed in the center of the insertion hole 45.
The drive shaft 3 is inserted through the cover 44.
A cylindrical portion 46 is formed to protrude from the surface opposite to the rotor, and a washer 48 is interposed between the cylindrical portion 46 and a flange 47 formed on the drive shaft 3. surrounded first
A seal chamber 49a is configured. Further, an annular groove 51 is formed on the surface of the rear part 1b that contacts the rotor 35 following one end of the drive shaft insertion hole 2, and a second annular groove 51 surrounded by the drive shaft 3, the plain bearing 4a, the rotor 35, and the annular groove 51 is formed. A seal chamber 49b is configured. Oil seals 50a and 50 made of rubber or the like are provided in the seal chambers 49a and 49b, respectively.
b are accommodated, and each seals the working chamber 41 of the feed pump 34 from the lubricating space to which lubricating oil is supplied.

That is, in this embodiment, the lubrication space is the drive shaft insertion hole 2 and the cam chamber 5 on both sides of the feed pump 34, and the rear portion 1b of the main body 1 has a lubricating oil inlet portion 52 formed in its upper part. At the same time, this lubricating oil inlet portion 52 and the drive shaft insertion hole 2,
A first oil hole 54 is formed that communicates with a lubricating oil reservoir 53 surrounded by the drive shaft 3 and plain bearings 4a and 4b, and lubricating oil such as engine oil flows from the lubricating oil inlet 52 into the lubricating oil reservoir chamber 53. is supplied to Further, second oil holes 55a, 55b are formed in the drive shaft 3 in the radial direction, one end of which opens on the inner surface of the plain bearings 4a, 4b, and the second oil holes 55a, 55b and the cam chamber A third oil hole 56 is formed in the axial direction to communicate with the drive shaft 3 and the plain bearing 4.
The lubricating oil squeezed by the clearance between the oil holes 55a and 4b flows through the second and third oil holes 55a, 55b, 56.
The water is supplied to the cam chamber 5 via the cam chamber 5. An overflow hole 57 is formed at a predetermined position in the cam chamber 5, so that when lubricating oil of a predetermined level or more accumulates in the cam chamber 5, excess lubricating oil is returned to the tank side.

Here, the following two points are particularly disclosed as new in this specification.

First of all, the cover 44 has a pressure relief passage 5.
8 is formed, this pressure relief passage 5
8 has one end opening into the first seal chamber 49a and the other end opening into the working chamber 41 near the fuel inlet 42. Therefore, the working chamber 4 on the outlet 43 side
When the fuel in No. 1 becomes high pressure, the pressure is applied to the rotor 35.
The fuel is transmitted to the seal chambers 49a, 49b through the clearance between the rear part 1b and the cover 44, and the fuel accumulated in the seal chambers 49a, 49b also becomes high pressure, and the fuel is transferred to the oil seals 50a, 50b.
The seal chambers 49a and 49b are kept under low pressure via the pressure relief passage 58, thereby preventing the pressure from escaping through the drive shaft insertion hole 2 or the cam chamber 5. Note that the first seal chamber 49a
and the second seal chamber 49b communicate with each other via the keyway 36a of the rotor 35, and are always maintained at approximately the same pressure.

Next, as shown in FIGS. 3 and 4, the vane 3
An equal pressure groove 59 is vertically formed in the front surface of the vane 9, and a back pressure chamber 60 is formed at the back of the vane 39 between the rotor 35 and the working chamber 4 preceding the vane 39.
1 are in communication with each other via the equal pressure groove 59, and this can prevent the vane 39 from retracting and causing the working chambers 41, 41 to communicate with each other. That is, the back pressure chamber 60 is located between the rotor 35 and the rear section 1.
High-pressure fuel leaks through the clearance between the seal chamber 49a and the cover 44 and is kept at a high pressure to prevent the vane 39 from being drawn in. However, as in this embodiment, the seal chambers 49a and 49b are kept at a low pressure. Then, the back pressure chamber 60 also becomes low pressure, the pressure from the working chamber 41 exceeds the pressure from the back pressure chamber 60, and the vane 3
There is a risk that 9 will be drawn in. Therefore, the above-described equal pressure groove 59 is formed in the vane 39 so that as the pressure in the working chamber 41 increases, the pressure in the back pressure chamber 60 also increases, and the pressure acting from the working chamber 41 on the vane 39 is reduced. It was made so that it could be fought against.

In the above configuration, when the drive shaft 3 rotates, the vane pump 34 is driven, the volume of the working chamber 41 increases and fuel is sucked into the working chamber 41 from the inlet 42, and the volume of the working chamber 41 decreases and fuel is sucked into the working chamber 41. The pressurized fuel is discharged from the fuel outlet 43 and reaches the inlet 24 of the solenoid valve 15 via the rear connector 31b, the connection pipe 33, the head connector 31a, and the communication path 32. At the same time, the rotation of the drive shaft 3 is transmitted to the plunger 8 via the coupling ring 12 and the cam disc 11.
performs reciprocating rotational motion, and during the suction stroke in which the plunger 8 retreats, the pressure within the pressure chamber 9 decreases, and during the discharge stroke in which the plunger 8 moves forward, the pressure in the pressure chamber 9 decreases.
The pressure inside increases.

However, if the excitation coil 19 of the solenoid valve 15 is demagnetized during the suction stroke of the plunger 8,
Since the solenoid valve 15 is opened, the feed pump 34
The fuel sent to the inlet 24 of the solenoid valve 15 is sucked into the pressure chamber 9 between the valve stem 21 and the valve seat 22 of the solenoid valve 15, through the outlet 25 of the solenoid valve 15, and the fuel suction passage 26. Ru. Subsequently, when the excitation coil 19 of the solenoid valve 15 is energized during the compression stroke, the solenoid valve 1
5 is closed, the fuel in the pressure chamber 9 is pressurized, and the vertical hole 28 of the plunger 8 and the discharge group 29
The fuel is sent out from the delivery section 30 through a distribution passage (not shown), and when the excitation coil 19 of the solenoid valve 15 is demagnetized during the compression stroke, the solenoid valve 15 is opened and the fuel injection is completed.

On the other hand, the lubricating oil is sent between the drive shaft 3 and the plain bearings 4a, 4b from the lubricating oil inlet 52 through the first oil hole 54 and the lubricating oil reservoir chamber 53 to lubricate these parts. Further, the oil is supplied to the cam chamber 5 through the second oil holes 55a, 55b and the third oil hole 56 of the drive shaft 3. The lubricating oil supplied to this cam chamber 5 is used to lubricate sliding parts such as the drive shaft 3, coupling 12, cam disk 11, etc., and the level of lubricating oil in this cam chamber 5 rises above the overflow hole 57. Then, it is returned to the tank side through this overflow hole 57.

Here, when the fuel from the feed pump 34 leaks into the drive shaft insertion hole 2 or the cam chamber 5, the lubricating oil is diluted.
Since the pressure in the oil seals 50a and 49b is designed to escape to the low pressure side of the feed pump 34 through the pressure relief passage 58 formed in the cover 44, the pressure of the fuel applied to the oil seals 50a and 50b is lowered, and the fuel leakage is prevented. can be prevented. Further, since the back pressure chamber 60 communicates with the working chamber 41 via the equal pressure groove 59 of the vane 39, the back pressure chamber 60
The force acting on the vane 39 from the working chamber 41 always exceeds the force acting on the vane from the working chamber 41, thereby preventing the vane 39 from being pulled into the back side of the vane groove 38.

In the above embodiment, lubricating oil is supplied to both the drive shaft insertion hole 2 and the cam chamber 5, but this invention can also be applied to a type in which lubricating oil is supplied to either one of them. can be applied. Further, in the above embodiment, a vane type feed pump is used as the feed pump 34, but other types such as a gear pump may also be used.Furthermore, the pressure relief passage 58 is not limited to the cover 44. For example, it may be formed in the rear portion 1b of the injection pump main body 1.

(Effects of the invention) As described above, according to this invention, an oil seal is used to seal between the lubrication space where lubricating oil is supplied and the feed pump which pressurizes the fuel.
Since the seal chamber in which this oil seal is placed and the low pressure side of the feed pump are communicated via a pressure relief passage, the seal chamber can always be kept at a low pressure, and fuel leakage from the feed pump to the lubrication space can be prevented. It is possible to ensure the performance of the lubricating oil over a long period of time, thereby contributing to extending the life of the equipment.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the distribution type fuel injection pump of this invention, FIG. 2 is a cross-sectional view taken along the line A-A in FIG. 1,
FIG. 3 is a side view of the feed pump used in the above embodiment, and FIG. 4 is a perspective view showing the vane of the feed pump. 2... Drive shaft insertion hole, 3... Drive shaft, 5... Cam chamber, 34... Feed pump, 35... Rotor, 39... Vane, 40... Guide ring, 41
... Working chamber, 49a, 49b ... Seal chamber, 50
a, 50b...oil seal, 59...equal pressure groove,
60...Back pressure chamber.

Claims (1)

[Claims for Utility Model Registration] 1. In a distribution type fuel injection pump in which a feed pump is provided adjacent to a lubricating space where lubricating oil is supplied, an oil feed pump provided around a drive shaft between the lubricating space and the feed pump 1. A distribution type fuel injection pump, characterized in that the oil seal is sealed, and the seal chamber in which the oil seal is disposed communicates with the low pressure side of the feed pump via a pressure relief passage. 2. A feed pump includes a rotor fixed to a drive shaft, a vane fitted into the rotor, and a guide ring that guides the tip of the vane, and has an operating chamber surrounded by the rotor, vanes, and guide ring. The fuel is pressurized by a change in volume of the vane, and an equal pressure groove is formed in the vane to communicate a back pressure chamber formed at the back of the vane with an operating chamber preceding the vane. A distribution type fuel injection pump according to claim 1 of the utility model registration claim.