JPH0874697A - Inner cam type fuel injection pump - Google Patents

Abstract

PURPOSE: To improve a pressure-fed efficiency of fuel by reducing the volume of a fuel passage in an inner cam type fuel injection pump appropriate to the fuel injection pump of a diesel engine. CONSTITUTION: Plungers 96a, 96b are inserted into the pump chamber 91 of a rotor 90. A cam ring having a plural number of cams on the inner circumferencial face is arranged on the outer circumference of the plungers 96a, 96b. A fuel supply port 101, and a fuel delivery port 102 are provided on a cylinder 100 rotatably holding the rotor 90. A fuel suction port 92, and a fuel discharge port 93 communicated with the fuel supply port 101, and the fuel delivery port 102 at a specified rotary angle are provided on the rotor 90. A first fuel passage 94 for communicating the fuel suction port 92 with the fuel discharge port 93, and a second fuel passage 95 for communicating a pump chamber 91 with the fuel suction port 92 are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inner cam type fuel injection pump, and more particularly to an inner cam type fuel injection pump suitable for a diesel engine fuel injection pump.

[0002]

2. Description of the Related Art Conventionally, as a fuel injection pump for a diesel engine, an inner cam type fuel injection pump as disclosed in, for example, Japanese Patent Laid-Open No. 61-96168 is known. Here, the inner-cam type fuel pump is provided with a rotor that rotates at half the rotational speed of the engine on the inner circumference of an inner cam fixed to the housing, and a plunger that is slidably inserted in the rotor radial direction. Is a fuel injection pump that is pressed by a cam surface formed on the inner circumference of the inner cam via a roller and a roller shoe.

That is, when the rotor rotates with respect to the housing, the plunger fitted into the rotor reciprocates following the lift change of the cam provided on the inner circumference of the inner cam. At this time, the fuel pressure in the center of the rotor, that is, in the pump chamber formed inside the plunger is increased when the plunger moves forward toward the center of the rotor. The increase in fuel pressure occurs when the rotation angle of the rotor reaches a predetermined rotation angle corresponding to the position of the cam provided on the inner surface of the inner cam.

Therefore, if the fuel pressure is appropriately distributed to the cylinders constituting the diesel engine, high pressure fuel can be supplied during the compression stroke in each cylinder, which is necessary for the fuel injection pump. Various functions can be realized. By the way, in order to specifically realize such a function, the fuel suction passage that sucks fuel into the pump chamber when the plunger moves back toward the outer circumference of the rotor, and the plunger moves forward toward the center of the rotor. At this time, it is necessary to provide a fuel discharge passage for discharging fuel from the pump chamber.

Further, in such a fuel injection pump, when a leak passage is provided so as to communicate with the pump chamber and the conduction of the leak passage is controlled, the pressure in the pump chamber is increased only when the leak passage is cut off, and the positive pressure is positively exerted. It is possible to control the fuel injection timing. Therefore, when realizing the inner cam type fuel injection pump, it is preferable to provide the fuel leak passage along with the fuel intake passage and the fuel discharge passage described above.

On the other hand, in the inner cam type fuel injection pump described in the above publication, a through passage that penetrates from the pump chamber to the tip thereof is provided in the longitudinal direction of the rotor, and the fuel intake passage and the fuel are branched from this through passage. By providing the discharge passage and the fuel leakage passage, each of the above passages is realized.

That is, the openings of the fuel intake passage, the fuel discharge passage, and the fuel leakage passage are opened on the outer periphery of the rotor, and the fuel that communicates with these openings on the cylinder side only at specific rotation angles. When the supply port, the fuel discharge port, and the fuel leak port are provided, it is possible to appropriately suck, discharge, and leak the fuel.

Therefore, according to the inner cam type fuel injection pump described in the above publication, the high pressure fuel can be appropriately supplied to the diesel engine with good control accuracy.

[0009]

However, when a through passage is provided so as to penetrate from the pump chamber to the rotor tip as in the above-mentioned conventional inner cam type fuel injection device, a blind passage is formed at the rotor tip to close the opening of the through passage. A stopper is required. That is, the rotor tip side opening of the through passage is an opening that is functionally unnecessary, and if the desired path can be realized without providing such an opening, no blind plug is required.

Further, in the structure in which the fuel pressure is increased by the operation of the plunger, the larger the volume change of the pump chamber due to the displacement of the plunger, the more advantageous the pressure increase of the fuel is. The smaller the volume, the more advantageous for boosting the pressure of the fuel.

On the other hand, the above-mentioned conventional device has a space that is unnecessary as a fuel flow passage in a part of the through passage, and also has a fuel suction passage, a fuel discharge passage, and a fuel leak passage. Since the dead volume is provided independently, it is preferable that the dead volume is as small as possible in order to secure the boosting characteristic at the time of fuel injection, and the dead volume is formed relatively large.

In this sense, the above-mentioned conventional inner cam type fuel injection device is contrary to the demand for reduction of the number of constituent parts and the demand for volume reduction of the dead volume in the fuel passage, which is necessarily in terms of cost and performance. There was a problem that the above optimization could not be realized.

The present invention has been made in view of the above points, and an inner cam type that solves the above problems is provided by sharing a part of the fuel suction passage and the fuel discharge passage communicating with the pump chamber. An object is to provide a fuel injection pump.

[0014]

The above-mentioned object is defined in claim 1.
As shown in FIG. 3, a rotor having a pump chamber inside and a fuel inlet and a fuel outlet communicating with the pump chamber at a predetermined position on the outer periphery, and the fitted rotor are rotatably held. At the same time, at least when the rotation angle of the rotor is a predetermined rotation angle that is the fuel intake stroke, a fuel supply port that communicates with the fuel intake port of the rotor, and a predetermined rotation angle that is the rotation angle of the rotor is the fuel discharge stroke. An inner-cam type fuel injection pump, comprising: a cylinder having a fuel outlet port that communicates with the fuel outlet of the rotor in some cases; wherein the fuel inlet and the fuel outlet of the rotor are the same as the fuel inlet. Communicating with the pump chamber via a first fuel passage communicating with the fuel discharge port, and a second fuel passage communicating with any one of the fuel suction port and the fuel discharge port with the pump chamber. It is achieved by that inner cam type fuel injection pump.

Further, as described in claim 2, the above-mentioned object is, in the inner cam type fuel injection pump according to claim 1, the first passage and the second passage are respectively connected to the fuel intake port. On a straight line connecting the fuel discharge port,
And an inner cam type fuel injection pump provided on a straight line connecting any one of the fuel suction port and the fuel discharge port to the pump chamber.

Further, in order to achieve the above object, as described in claim 3, a pump chamber is provided inside, and a fuel intake port communicating with the pump chamber is provided at a predetermined position on the outer circumference.
And a rotor provided with a fuel discharge port, and a rotatably holding the inserted rotor, and a fuel suction port of the rotor when at least the rotation angle of the rotor is a predetermined rotation angle for a fuel suction stroke. An inner-cam fuel injection system including: a cylinder having a fuel supply port communicating with each other; and a fuel outflow port communicating with the fuel discharge port of the rotor when the rotation angle of the rotor is a predetermined rotation angle corresponding to a fuel discharge stroke. In the pump, the rotor is provided with an annular groove communicating with the fuel discharge port on its outer circumference, and the cylinder is provided with a fuel leakage passage communicating with the annular groove. The inner cam type fuel injection pump having a smaller diameter than other parts is also effective.

[0017]

In the invention of claim 1, when the rotation angle of the rotor with respect to the cylinder reaches a predetermined rotation angle for fuel suction, the pump chamber communicates with the fuel supply port through the fuel suction port. Then, the fuel is sucked into the pump chamber.

When the rotation angle of the rotor with respect to the cylinder reaches a predetermined rotation angle for fuel injection,
The pump chamber communicates with the fuel outlet through the fuel outlet. In this case, the fuel intake port and the fuel supply port are cut off, the fuel pressure generated in the pump chamber is released only from the fuel discharge port, and high-pressure fuel injection is realized.

By the way, in the present invention, the first fuel passage communicates with the fuel inlet and the fuel outlet, and the second fuel passage includes either the fuel inlet or the fuel outlet. Since the one is communicated with the fuel pump, the second fuel passage is used both as a path for inhaling fuel and a path for injecting fuel.

Therefore, in the present invention, only the space that is truly necessary for performing the suction and the injection of the fuel is in communication with the pump chamber, which corresponds to the boosting capacity of the pump chamber. Therefore, high pumping efficiency can be obtained, and excellent boosting characteristics are realized as an inner cam type fuel injection pump.

Further, in the second aspect of the invention, the shortest path through which the first fuel passage and the second fuel passage communicate with the pump chamber, the fuel suction port, and the fuel discharge port, respectively. Provided on top. Therefore, the volume of the space provided in communication with the pump chamber becomes the minimum necessary volume, and with respect to the fuel boosting capacity in the pump chamber,
As an inner cam type fuel injection pump, high pumping efficiency can be obtained.

Further, in the invention according to claim 3, the rotor is provided with the annular groove in communication with the discharge port. Further, the cylinder has a fuel leak passage communicating with the annular groove. Therefore, the fuel discharge port is always in communication with the fuel leak passage, and the fuel pressure does not increase unless the fuel leak passage is blocked. That is, the annular groove and the fuel leak passage are
It is possible to realize highly accurate fuel injection timing control of the inner cam type fuel injection pump according to the present invention.

By the way, the annular groove is a space which always communicates with the pump chamber, and the larger the volume thereof, the more disadvantageous from the viewpoint of ensuring high pumping efficiency. On the other hand, from the viewpoint of ensuring a high degree of freedom in controlling the fuel injection timing, it is desirable to always maintain the communication between the fuel injection port and the fuel leakage passage, and thus the annular groove is used for the rotor. It is desirable to provide it all around.

On the other hand, the rotor is provided such that the diameter of the rotor in the vicinity of the annular groove is smaller than that of other portions. Therefore, the volume of the annular groove is suppressed to be relatively small, and despite the annular groove being provided over the entire circumference of the rotor, excellent boosting characteristics are ensured with high pumping efficiency.

[0025]

1 is a front sectional view showing the overall structure of an inner cam type fuel injection pump 10 according to an embodiment of the present invention. In the figure, the housing 11 is a fuel injection pump 1.
A fuel chamber 12 for accommodating each functional component of the fuel injection pump 10 and filled with fuel therein.
It has.

The housing 11 has an overflow valve 2 which communicates with a predetermined position of the fuel chamber 12.
0, a spill valve 30, a fuel recirculation valve 40, an accumulator 50, and a constant pressure valve 60. The overflow valve 20 is a valve that prevents the pressure in the fuel chamber 12 from becoming excessive, and includes a check valve including a ball valve 22 and a spring 24. When the fuel is excessively supplied to the fuel chamber 12, the overflow valve 20 is provided. , The excess is returned to the fuel tank. In this embodiment, the valve opening pressure is set to about 0.8 kg / cm ² .

The spill valve 30 is an electromagnetic valve that opens and closes the valve element 32 by the electromagnetic force generated by the electromagnetic coil 31.
A fuel recirculation valve 40 and a fuel intake gallery 17 described later.
And controlling electrical connection with a fuel leakage passage 103 described later.
The valve body 32 of the spill valve 30 is biased upward by a spring 33, and the upper end thereof is supported by a rod 34 that transmits the electromagnetic force generated by the electromagnetic coil 31 and a stopper 36 that is biased by a spring 35. It is regulated.

On the other hand, the valve body 32 and its valve seat 37 are
When 2 is seated on the valve seat 37, that is, when the spill valve 30 is closed, hydraulic pressure acts only on the side surface of the valve body 32, and the valve body 32 separates from the valve seat 37. When the spill valve 30 is open, the hydraulic pressure is also applied to the tip surface of the valve element 32.

That is, when the electromagnetic coil 31 generates an electromagnetic force and the rod 34 presses the valve body 32, the thrust force of the rod 34 and the urging force of the spring 35 act on the valve body 32 in the valve closing direction. As a result, the valve body 32 is displaced against the biasing force of the spring 33, and the spill valve 30 is closed.

When the thrust of the rod 34 disappears,
The urging force of the spring 33 displaces the valve body 32 in the valve opening direction against the urging force of the spring 35, and the spill valve 3
0 is open. At this time, since a hydraulic pressure that presses the valve body 32 in the valve opening direction acts on the tip of the valve body 32, the higher the hydraulic pressure is, the greater the degree of opening of the spill valve 30 is secured.

The fuel recirculation valve 40 is the spill valve 30.
This valve is provided to appropriately depressurize the fuel leaked from the fuel leak passage when the valve is opened and to recirculate it to the fuel tank. Like the overflow valve 20 described above, it is a reverse valve including a ball valve 42 and a spring 44. It consists of a stop valve.

Further, the accumulator 50 is arranged to absorb the pulsation of the fuel pressure in the fuel intake gallery 17, and the piston 52 is displaced in accordance with the pressure fluctuation of the fuel chamber communicating with the fuel intake gallery 17. , And a spring 54 for urging the piston 52.

The constant pressure valve 60 is a valve provided between the fuel outflow port 102 in the housing 11 described later and the fuel injection valve provided in each cylinder of the internal combustion engine. When the pressure exceeds a predetermined pressure and becomes high, the fuel flows toward the fuel injection valve at that pressure, and the fuel outflow port 10
It has a function of keeping the pressure on the fuel injection valve side at a predetermined pressure even when the internal pressure of 2 becomes equal to or lower than the predetermined pressure.

In the fuel chamber 12 of the housing 11,
A drive shaft 70 that rotates at half the rotational speed of a crankshaft of an internal combustion engine, and a vane fuel feed pump (hereinafter simply referred to as a feed pump) 80 that feeds fuel using the rotational force of the drive shaft 70 as a drive source. , Drive shaft 70
A rotor 90 that rotates together with it, a cylinder 100 into which a small diameter portion of the rotor 90 is inserted, and a cam ring 110 that surrounds the outer circumference of the large diameter portion of the rotor 90 are incorporated.

The drive shaft 70 is rotatably held with respect to the housing 11 by a bush 13 arranged near the end of the housing 11 and a rotary bearing 14 arranged inside the housing 11. Where bush 13
In order to reduce the sliding resistance, fuel is supplied, and an oil seal 14 is provided at the end of the fuel, and an oil passage 16 is provided to connect the fuel inlet 15 and the bush 13. .

Here, the drive shaft 70 has a pulsar 1 provided with projections 121 provided on the outer periphery of the drive shaft 70 at predetermined intervals.
20 is inserted and the cam ring 110 is
A rotation angle sensor 122 that converts proximity / separation of the protrusion 121 into a pulse signal is fixed.

That is, in the fuel injection pump of this embodiment, the rotation angle of the drive shaft 70 with respect to the cam ring 110, that is, the rotor 90 with respect to the cam ring 110, is counted by counting the number of pulses generated by the rotation angle sensor 122.
It is possible to detect the rotation angle of.

The feed pump 80 is a vane type pump having an outer wall 81 fixed to the housing 11 and a rotor 83 having a plurality of vanes 82. That is, the fuel sucked from the suction port 84 provided in communication with the fuel inlet 15 is pressurized by the vanes 82 as the rotor 83 rotates and is discharged from the fuel discharge port 85 provided at a predetermined position. .

The rotor 90 is an essential part of the fuel injection pump of this embodiment, and is rotatably fitted in the cylinder 100 while being engaged with the drive shaft 70. Here, the rotor 90 has a large diameter portion that communicates with the pump chamber 91 and a small diameter portion that communicates with the fuel suction port 92 and the fuel discharge port 93, and the fuel suction port 92 and the pump chamber. It has the 2nd fuel passage 95 which connects with 91.

Plural plungers (four in this embodiment) 96a to 96d capable of sliding in the radial direction of the rotor 90 are inserted in the pump chamber 91, and the fuel discharge port 93 has a shaft. An annular groove 97 surrounding the outer circumference of the rotor 90 is communicated at a position offset in the direction.

On the other hand, in the cylinder 100, a fuel supply port 17 of the feed pump 80 and a fuel supply port communicating with the inner periphery of the cylinder 100 and a fuel suction gallery 17 which communicates with each other through an external pipe (6 in this embodiment). One) 101 _-1
And to 101 _-6, one end communicated with the above-mentioned constant pressure valve 60 in its outer periphery, the other end the cylinder 1
A plurality of fuel outflow ports (six in this embodiment) 102 _{-1 to} 102 _{-6 that} are open to the inner circumference of 00 are provided.

Here, each fuel intake port 101_-1-10
1_-6, And each fuel outflow port 102 _-1-10_-6Is that
Each cylinder of the internal combustion engine (6 cylinders in this embodiment)
Is a port provided corresponding to the
The rotation of the internal combustion engine when rotating in synchronization with the rotation angle of the engine
Depending on the corner, the fuel intake gallery 17
A console connected to the suction port 92 and arranged in a specific cylinder
The fuel outlet 93 is attached to the tanto pressure valve 60.
Communicate.

The cylinder 100 is provided with a leak passage 103 for communicating the annular groove 97 provided in the rotor 90 with the spill valve 30. Here, the annular groove 97 is
As described above, the groove is provided over the entire circumference of the rotor 90. Therefore, the annular groove 97 and the spill valve 30 are always in communication with each other regardless of the rotation angle of the rotor 90.

The configuration around the pump chamber 91 will be described below with reference to FIG. 2 corresponding to the II-II section in FIG.
That is, the fuel injection pump 10 according to the present embodiment includes the rotor 9
This is a pump that boosts the pressure of fuel by driving four plungers 96a to 96d inserted in 0 with cams provided on the cam ring 110.

Since the fuel pump 10 of this embodiment is compatible with the 6-cylinder internal combustion engine as described above,
The cam ring 110 is provided with six cams at equal intervals as shown in FIG.
The positions of a to 96d are designed so that all the plungers 96a to 96d are lifted at the same time.

Roller shoes 98a to 98d and roller shoes 98a to 9d are provided on the outer circumferences of the plungers 96a to 96d in order to smoothly transmit the cam lift provided by the cam ring to the plungers 96a to 96d.
Rollers 99a to 99d gripped by 8d are arranged.

Therefore, when the rotor 90 rotates inside the cam ring 110, the plungers 96a to 96d reciprocate six times while the rotor 90 makes one revolution, and the reciprocating motion causes the fuel in the pump chamber 91 to be replenished. If the pressure is increased, the fuel pressure is increased six times for each equal rotation angle while the rotor 90 makes one rotation, that is, while the internal combustion engine makes two rotations.

At this time, the fuel supply port 101 shown in FIG.
_{-1 to} 101 _-6 and the fuel intake port 92 are connected to the plunger 96a.
.About.96d are configured to communicate with each other under the condition that no cam lift is applied. Also, the fuel outflow port 102 _-1
To 102 _-6 and the fuel discharge port 93, the plunger 96a~
It is configured to communicate immediately before a lift occurs in 96d.

Therefore, as the rotor 90 rotates, one of the fuel supply ports 101 _{-1 to} 101 _-6 and the fuel intake port 9
When the two communicate with each other, the centrifugal force and the fuel pressure supplied from the feed pump 80 act on the plungers 96a to 96d, and the fuel is sucked into the pump chamber 91.

Then, after that, the fuel supply ports 101 _-1 to
When the plungers 96a to 96d are lifted in a state where the communication between 101 _-6 and the fuel suction port 92 is cut off, and then the fuel outflow ports 102 _{-1 to} 102 _-6 and the fuel discharge port 93 communicate with each other, the spill valve 30 is activated. High pressure fuel is supplied to the constant pressure valve 60 on the assumption that the valve is closed.

By the way, when the pressure of the fuel is increased by the plungers 96a to 96d, the spill valve 30 described above is used.
When the valve is open, the fuel pressure-fed from the pump chamber 91 flows back to the fuel tank or the like via the spill valve 30, and high-pressure fuel is not supplied to each cylinder.

That is, assuming that the spill valve 30 does not exist, the fuel injection timing for each cylinder is uniquely determined by the cam profile provided on the cam ring 110, and the degree of freedom regarding fuel injection timing control is significantly lost. It will be in a state of being. On the other hand, in the configuration having the spill valve 30 as in this embodiment, the pump chamber 91
Even if the pressurization is started at, the fuel injection is not performed as long as the spill valve 30 is opened as described above. In this sense, the fuel is injected by controlling the timing of switching the spill valve 30 from the open state to the closed state. By controlling the injection start timing and then the timing of opening the spill valve 30 again, the fuel injection end timing can be accurately controlled.

In this embodiment, the rotor 90 has an annular groove 97.
And the fuel leak passage 103 is provided in the cylinder 100,
Further, the spill valve 30 for controlling the conduction of the fuel leakage passage 103 is provided in order to realize the fuel injection timing control as described above. In this case, in order to control the fuel injection end timing with high accuracy, it is more advantageous that the leakage capability when the spill valve 30 is opened is higher. On the other hand, securing a large stroke amount of the valve body 33 of the spill valve 30 or enlarging the area of the valve body 33 leads to an increase in the size of the spill valve 30 and is disadvantageous in terms of ensuring responsiveness. Occurs.

As described above, by urging the stopper 36 for restricting the upper end of the valve body 33 with the spring 33, the valve body 33
The reason why the larger opening degree is obtained as the hydraulic pressure is higher when the valve is opened is to meet such a requirement. That is, according to the spill valve 30 of the present embodiment, it is possible to secure a high leakage capacity in the early stage of fuel leakage without increasing the size of the body and deteriorating the responsiveness at the time of opening / closing the valve, and to provide an excellent fuel exhaustion characteristic Can be secured.

When leaking the high-pressure fuel using the spill valve 30, the first and second passages 9 provided in the rotor 90 are caused by the inertial effect of the fuel at the time of the leak.
The internal pressure of 4, 95 may become negative. When the internal pressure in these passages becomes negative, the plungers 96a-9a
The relationship of the amount of fuel pumped with respect to the stroke of 6d changes, and the control accuracy of the fuel injection amount deteriorates.

In the present embodiment, a part of the fuel leaked through the spill valve 30 is returned to the fuel intake gallery 17, and the accumulator 50 is provided in communication with the fuel intake gallery 17 to prevent such an adverse effect. This is for effective removal. That is, in the fuel injection pump 10 of the present embodiment, since the above-described configuration is adopted, even if excessive fuel leakage occurs due to the inertial effect at the time of fuel leakage, part of it will be the fuel intake gallery. 17
The internal pressure pulsation caused by the leaked fuel being recirculated is appropriately absorbed by the accumulator 50, so that a sufficient amount of fuel can be stably sucked at the time of the next fuel suction. It is possible.

Further, the fuel injection pump 10 of this embodiment is
A timer device 130 for changing the fixed angle of the cam ring 110 with respect to the housing 11 is provided. That is, the cam ring 110 is rotatably assembled to the howling 11, and is further fixed to a rod 133 sandwiched between timer pistons 131 and 132, as shown in FIG.

Here, the timer pistons 131 and 132
2 is a piston slidably inserted into the timer device 130. In FIG. 2, a high pressure chamber 134 communicating with the fuel discharge port 85 of the feed pump 80 is provided on the right side of the timer piston 131. On the left side of 132, the low pressure chamber 1 communicating with the fuel intake port 84 of the feed pump 80.
35 are formed respectively.

A spring 136 for urging the timer piston 132 to the right in FIG. 2 is arranged in the low pressure chamber 135, and the high pressure chamber 134 and the low pressure chamber 135 are electrically connected by the solenoid valve 140 shown in FIG. Are connected by external pipes that are controlled. In this case, the high pressure chamber 134 and the low pressure chamber 135
The cam ring 110 rotates in accordance with the pressure difference between and, and in this embodiment, the opening / closing valve of the solenoid valve 140 is duty-controlled to control the rotation angle to a desired value.

With this structure, the plunger 9 with respect to the rotation angle of the rotor 90, that is, the rotation angle of the internal combustion engine.
It is possible to change the lift characteristics of 6a to 96d, so that it is possible to further increase the degree of freedom regarding fuel injection timing control, and a fuel injection pump with excellent controllability is realized.

By the way, the fuel injection pump 10 of the present embodiment.
As described above, in the pump that boosts the pressure of fuel by the reciprocating motion of the plungers 96a to 96d, the plungers 96a to 96d
The higher the displacement speed of 96d, the higher the pumping efficiency can be obtained. However, in order to increase the displacement speed,
Since it is necessary to use a cam whose lift amount changes abruptly, the displacement speed cannot be increased indefinitely in the sense of ensuring smooth operation.

On the other hand, in order to increase the pumping efficiency of the fuel injection pump 10, it is effective to reduce the total volume of the space communicating with the pump chamber 91 in order to suppress the pressure consumption in the fuel outflow path. The larger the volume of the path unnecessary for injection, that is, the larger the dead volume, the lower the pumping efficiency at the time of fuel injection.

In this sense, it is necessary to reduce the dead volume as much as possible in order to obtain high pumping efficiency while ensuring smooth operation in the inner cam type fuel injection pump. The fuel injection pump 10 of the present embodiment is characterized in that a fuel passage shape with a small dead volume is adopted, paying attention to such a point.
Specific effects of the fuel injection pump 10 will be described below with reference to FIGS. 3 and 4.

That is, from the viewpoint of realizing the function as the inner-cam type fuel injection pump, the rotor 90 has a suction port for communicating the fuel supply port of the cylinder with the pump chamber 91 at the timing of sucking fuel into the pump chamber 91. The passage, the discharge passage communicating the fuel outlet port of the cylinder with the pump chamber 91 at the timing when the pump chamber 91 pumps fuel, and the discharge passage 103
It is sufficient to have a leak path that opens to the outside.

FIG. 3 is a diagram showing an example of the rotor 90 having a fuel passage that meets the above conditions. That is, in the rotor 90 shown in the figure, a main fuel passage 150 is provided which penetrates the pump chamber 91 from the left side of the pump chamber 91.
From the main fuel passage 150 to the fuel supply port 10
1 or a branch passage 151, 152 branching toward the fuel leak passage 103, and a fuel discharge port 153 communicating with the fuel outflow port 102 only at a specific rotation angle, and an annular groove 154 communicating with the branch passage 152. And are provided.

In this case, when the rotor 90 is provided with an appropriate rotation angle, the pump chamber 91 communicates with the fuel supply port via the main fuel passage 150 and the branch passage 151, so that the fuel can be sucked. is there. Further, when the rotor 90 is given an appropriate rotation angle, the pump chamber 91 communicates with the fuel outflow port via the main fuel passage 150, the branch passage 152, the annular groove 154, and the fuel discharge port 154. Can be discharged.

Then, regardless of the rotation angle of the rotor 90,
Pump chamber 9 through main fuel passage 150 and annular groove 153
1 communicates with the leakage passage 103, so that the spill valve 30 can appropriately control the fuel injection timing.
However, the configuration shown in FIG. 3 is not an optimization for saving the dead volume described above, but is a configuration that emphasizes functions. Furthermore, since the main fuel path 150 is provided so as to penetrate the pump chamber 91, the blind plug 155 is required to ensure the desired sealing performance.

On the other hand, in the fuel injection pump 10 of this embodiment, as shown in FIG. 4 (the same as FIG. 1), the fuel intake port 92.
By communicating the fuel discharge port 93 with the fuel discharge port 93 by the first fuel passage 94, the second fuel passage 95 is commonly used for the fuel suction passage and the fuel discharge passage.

In this case, at the time of fuel injection, the pump chamber 9
There is no fuel passage other than the path connecting 1 and the fuel discharge port 93, and the dead volume in the distribution path is virtually eliminated. Further, since the first and second fuel passages are both linearly provided, the fuel passage that is functionally required can be realized with the minimum volume.

Further, in such a structure, if the second fuel passage 95 is formed from the fuel intake port 92 side toward the pump chamber 91, it is also necessary to dispose the blind plug 155 on the back surface of the pump chamber 91. Disappear. In this sense, the first and second fuel passages formed in the rotor 90 of the present embodiment have an ideal shape in order to reduce the number of parts and to realize high pressure feeding efficiency. That is, according to the present embodiment, it is possible to enjoy the effect that the cost can be reduced while improving the fuel pumping capacity.

By the way, the unnecessary fuel passage at the time of fuel injection is a dead volume from the viewpoint of ensuring high pumping efficiency, and the existence thereof is not preferable, as described above. For example, in Figure 4 above
The volumes of the middle, annular groove 97 and leak passage 103 are undesired dead volumes for improving the pumping efficiency. Therefore, if the volume can be reduced, it is possible to secure even more excellent pumping efficiency characteristics. Hereinafter, the configuration of the rotor 60 designed in consideration of such a point will be described with reference to FIG.

FIG. 5 shows a front sectional view of a second embodiment of a rotor used in an inner cam type fuel injection pump according to the present invention. The rotor 160 shown in FIG. 5 has a configuration in which the rotor diameter in the vicinity of the portion where the annular groove 161 is provided for communicating the fuel leakage passage 103 and the pump chamber 91 is made smaller than the other portions. In this case, the dead volume formed by the annular groove 161 is reduced in volume without impairing the fuel leakage capacity, and the above-described excellent effect is realized.

Therefore, when the fuel injection pump 10 is constructed by using the rotor 160 shown in FIG. 5, more excellent fuel pumping efficiency is obtained as compared with the case where the rotor 90 shown in FIG. 1 (FIG. 4) is used. You can By the way, the fuel injection pump 10 shown in the above embodiment is provided with the fuel passages (first and second fuel passages 94, 9) provided in the rotors 90, 161.
In addition to the volume saving of 5), the volume of the fuel passage provided in the cylinder 100 and the housing 11 is also reduced.

That is, in the fuel injection pump 10, as shown in FIG. 1, each of the fuel supply ports 101 _-1 to 101 _-1
01 _-6 to corresponding constant pressure valve 6
The fuel path leading to 0 is provided in a substantially straight line, and consideration is given to minimize a decrease in pumping efficiency in the path.

In the fuel injection pump 10 of this embodiment, since the pump chamber 91 and the fuel suction port 92 of the rotors 90 and 160 are designed to be close to each other, the passage connecting the pump chamber 91 and the fuel suction port 92 to each other. Is used as the second fuel passage 95, but the present invention is not limited to this, and when the pump chamber 91 and the fuel discharge port 93 are close to each other, the pump chamber 91 and the fuel discharge port 93 are connected to each other and the second fuel passage 95 is connected. It may be a passage.

FIG. 6 is a front sectional view of a third embodiment of the rotor used in the inner cam type fuel injection pump according to the present invention. In FIG. 6, the same parts as those shown in FIGS. 4 and 5 are designated by the same reference numerals, and the description thereof will be simplified or omitted. The rotor 170 shown in FIG.
It is inserted in the inside of 80. Similar to the cylinder 100 described above, the cylinder 180 is provided with a fuel leak passage 103 that communicates with the spill valve 30 and a fuel outflow port 102 that communicates with the contact pressure valve 60 of each cylinder. On the other hand, the rotor 170 has the same fuel leakage passage 103 of the cylinder 180 as the rotor 90 described above.
To the fuel outlet port 102 _{-1 to} 102 _-6 at a predetermined rotation angle.
Is provided, and the fuel discharge port 93 and the pump chamber 9 are provided.
A fuel passage 172 that linearly connects the fuel cell 1 and the fuel cell 1 is provided. In this embodiment, the fuel leak passage 103 provided in the cylinder 180 and the annular groove 9 provided in the rotor 170 are provided.
7 functions as a passage for leaking fuel and also as a passage for guiding the fuel to the pump chamber 91.

That is, the inner cam type fuel injection pump 10 of this embodiment has the plungers 96a-96 as described above.
After the fuel is pumped by d, fuel injection is started by closing the spill valve 30 at an appropriate timing, and then the spill valve 30 is restarted at an appropriate timing.
The fuel injection is completed by opening the valve. Therefore,
The spill valve 30 is always open during the process of drawing fuel into the pump chamber 91 in preparation for fuel injection. The spill valve 30 includes the fuel leak passage 103, as described above,
It is a valve mechanism that connects or disconnects with the fuel intake gallery 17. Therefore, when the spill valve 30 is opened, the fuel leak passage 103 and the fuel intake gallery 17 are brought into conduction.

The pump chamber 91 of the rotor 170 is always connected to the fuel leak passage 103 through the fuel passage 172, the fuel discharge port 93, and the annular groove 97. Therefore, when the fuel leak passage 103 and the fuel suction gallery 17 are brought into conduction, the pump chamber 91 is also brought into conduction with the fuel suction gallery 17. Therefore, according to the configuration of the present embodiment, when the plungers 96a to 96d are displaced in the fuel intake direction inside the rotor 170, the fuel leakage passage 10 is displaced according to the displacement.
3, the fuel flows into the pump chamber 91 through the annular groove 97. Further, when the fuel injection timing is reached thereafter, the spill valve 30 causes the fuel leakage passage 10
3 is cut off, and the pressure of the fuel in the pump chamber 91 is appropriately increased.

As described above, according to the structure of this embodiment, it is not necessary to provide the fuel supply port in the cylinder 180, and the fuel discharge port 93 and the pump chamber 9 are provided inside the rotor 170.
Since only the fuel passage 172 that linearly communicates with 1 is provided, the dead volume in the fuel distribution path can be suppressed to the minimum. Furthermore, the above configuration
From the side of the fuel discharge port 93 toward the pump chamber 91, the fuel passage 1
By forming 72, it can be realized without using a blind plug. In this sense, the rotor 17 of this embodiment is
0 has an excellent effect in reducing the number of parts and improving the pumping efficiency.

In the rotor 170 shown in FIG. 6, the annular groove 97 is provided at the fuel inlet port and the fuel outlet port 9
3 corresponds to the above-mentioned fuel discharge port and the first fuel passage, and the fuel passage 172 corresponds to the above-mentioned second fuel passage.

[0081]

As described above, according to the first aspect of the present invention, the second passage is used as the fuel intake passage and the fuel injection passage, and together with the first fuel passage. It is possible to realize a structure in which only the necessary fuel passage communicates with the pump chamber. Therefore, according to the inner cam type fuel injection pump of the present invention, it is possible to suppress a decrease in the fuel pressure in the process from the pump chamber to the fuel injection port, and to provide a high fuel injection pressure with excellent boosting characteristics. Can be secured.

Further, according to the second aspect of the present invention, only the passages necessary for fuel supply and injection are communicated with the pump chamber, and the shortest passages of the first and second passages communicated with each other. Since this is achieved, ideal volume saving of the space communicating with the pump chamber is realized. For this reason,
According to the inner cam type fuel injection pump of the present invention, it is possible to obtain a more excellent boosting characteristic as compared with the invention according to claim 1.

Further, according to the third aspect of the present invention, by making the rotor diameter near the annular groove small, it is possible to form the annular groove over the entire circumference of the rotor with a relatively small volume. Therefore, according to the inner cam type fuel injection pump of the present invention, it is possible to form a path for always communicating the fuel discharge port with the fuel leak passage without increasing the volume of the space communicating with the pump chamber. Therefore, it is possible to achieve both highly accurate fuel injection timing control and high pumping efficiency.

[Brief description of drawings]

FIG. 1 is a front sectional view showing the overall configuration of an inner cam type fuel injection pump according to an embodiment of the present invention.

FIG. 2 is a side sectional view showing a configuration around a pump chamber of the inner cam type fuel injection pump of the present embodiment.

FIG. 3 is a front sectional view of an example of a rotor that can be used in the inner cam type fuel injection pump of the present embodiment.

FIG. 4 is a front sectional view of a first embodiment of a rotor used in the inner cam type fuel injection pump of this embodiment.

FIG. 5 is a front sectional view of a second embodiment of a rotor used in the inner cam type fuel injection pump of this embodiment.

FIG. 6 is a front sectional view of a third embodiment of a rotor used in the inner cam type fuel injection pump of this embodiment.

[Explanation of symbols]

10 Fuel injection pump 20 Overflow valve 30 Spill valve 40 Fuel recirculation valve 50 Accumulator 60 Constant pressure valve 70 Drive shaft 80 Feed pump 90,160,170 Rotor 91 Pump chamber 92 Fuel intake port 93 Fuel discharge port 94 First fuel passage 95 Fifth 2 Fuel passage 96a-96d Plunger 97,161 Annular groove 100 Cylinder 101 _{-1 to} 101 _-6 Fuel supply port 102 _{-1 to} 102 _-6 Fuel outflow port 103 Leakage passage 172 Fuel passage

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Nagatani 1-1, Showa-cho, Kariya city, Aichi Nihon Denso Co., Ltd.

Claims (3)

[Claims] 1. A rotor having an internal pump chamber, a fuel intake port communicating with the pump chamber and a fuel discharge port at a predetermined position on the outer circumference, and the rotor inserted therein is rotatably held. And a fuel supply port communicating with the fuel intake port of the rotor at least when the rotation angle of the rotor is a predetermined rotation angle for the fuel intake stroke, and a predetermined rotation angle for which the rotation angle of the rotor is the fuel discharge stroke. An inner cam fuel injection pump comprising: a cylinder having a fuel outlet port that communicates with the fuel outlet of the rotor, wherein the fuel inlet and the fuel outlet of the rotor are To the pump chamber via a first fuel passage communicating with the fuel discharge port, and a second fuel passage communicating with any one of the fuel suction port and the fuel discharge port with the pump chamber. Communicating Inner cam type fuel injection pump characterized by passing through. 2. The inner cam fuel injection pump according to claim 1, wherein the first passage and the second passage are on a straight line connecting the fuel inlet and the fuel outlet, respectively, and the fuel. An inner cam type fuel injection pump, which is provided on a straight line connecting one of the suction port and the fuel discharge port and the pump chamber. 3. A rotor having an internal pump chamber and a fuel inlet and a fuel outlet communicating with the pump chamber at a predetermined position on the outer circumference, and the rotor inserted and held so as to be rotatable. And a fuel suction port communicating with the fuel suction port of the rotor when at least the rotation angle of the rotor is a predetermined rotation angle for the fuel suction stroke, and a predetermined rotation angle for which the rotation angle of the rotor is the fuel discharge stroke. An inner cam fuel injection pump comprising: a cylinder having a fuel outflow port communicating with the fuel discharge port of the rotor; and wherein the rotor has an annular groove that communicates with the fuel discharge port. And the cylinder has a fuel leakage passage communicating with the annular groove, the rotor diameter in the vicinity of the annular groove is smaller than other portions. Inner cam type fuel injection pump to be.