JP3545594B2 - High pressure fuel pump for in-cylinder injection - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a high-pressure fuel pump for an in-cylinder injection engine, and more particularly to a high-pressure fuel pump for in-cylinder injection that does not spread pulsation to a feed-side fuel pipe.
[0002]
[Prior art]
A diesel engine is widely known as a so-called in-cylinder injection type engine or direct injection type engine in which fuel is injected into a cylinder of the engine. In recent years, a spark ignition engine (gasoline engine) has been widely used. ) Also proposes an in-cylinder injection type. Whereas the fuel pressure of the fuel supplied to the engine that creates the mixture outside the conventional cylinder is about 0.3 MPa, such a direct injection engine has, for example, , A fuel pressure of about 5 MPa is required.
[0003]
In order to obtain such a high fuel pressure, a high-pressure fuel pump is generally provided on the fuel injector side in addition to the low-pressure fuel pump provided in the fuel tank. In general, the low-pressure fuel pump is driven by, for example, a motor or the like, and is always driven when the power is turned on, whereas the high-pressure fuel pump is driven by the engine and rotates with the rotation of the engine.
[0004]
FIG. 5 is a side view of a part of a conventional in-cylinder high pressure fuel pump for injection. In FIG. 5, a suction passage 2, a discharge passage 3, and a drain 4 are formed in a casing 1 of the high-pressure fuel supply pump 100. The suction passage 2 communicates with a feed-side fuel pipe (not shown) extending from the low-pressure fuel pump. On the other hand, the discharge passage 3 communicates with a high-pressure side fuel pipe (not shown) leading to the fuel injector. The drain 4 communicates with a fuel tank (not shown).
[0005]
A cylindrical storage recess 1a is formed below the casing 1 in FIG. A cylinder 6 is provided in the storage recess 1a. The cylinder 6 includes a substantially cylindrical cylinder portion 6a and a flange portion 6b provided on one side of the cylinder portion 6a. The cylinder 6 is disposed with the flange 6b side facing the bottom 1b of the storage recess 1a.
[0006]
The reed valve 8 is sandwiched between two plates sandwiched between the bottom 1b and the cylinder 6. The reed valve 8 is provided with a suction valve and a discharge valve (not shown) at positions corresponding to the suction passage 2 and the discharge passage 3. Further, a return hole 4 a is provided at a position corresponding to the drain 4.
[0007]
In the cylinder portion 6a of the cylinder 6, a substantially cylindrical plunger 9 is disposed so as to be able to reciprocate. The plunger 9 forms a fuel pressure increasing chamber 10 together with the cylinder portion 6a. A compression coil spring 11 is housed in the fuel booster chamber 10 in a contracted state.
[0008]
A housing 12 is provided around the cylinder 6 so as to surround the cylinder 6. The housing 12 has a substantially bottomless bowl shape and has the cylinder portion 6a penetrated therethrough. A holder 13 is fixed to an end of the plunger 9 opposite to the fuel pressure increasing chamber 10. A metal bellows 14 is provided between the housing 12 and the holder 13. The bellows 14 and the housing 12 form a closed space 16 for storing therein fuel leaked from between the plunger 9 and the cylinder 6. The drain 4 returns the fuel extending from the capture space 16 and accumulated in the capture space 16 to a fuel tank (not shown).
[0009]
A cylindrical tappet 18 with a bottom is in contact with the end of the plunger 9 on the side opposite to the fuel pressure increasing chamber 10. The tappet 18 has a cam roller 18a inside. A compression coil spring 19 is contracted between the housing 12 and the tappet 18.
[0010]
A bracket 20 is provided around the compression coil spring 19. The bracket 20 has a substantially cylindrical shape having a flange portion 20a at an intermediate portion. In the bracket 20, the casing 1 is also fastened to the flange portion 20a by a bolt (not shown), and the cylinder 6 and the housing 12 are fixed to the casing 1 by pressing the edge of the housing 12 at one end.
[0011]
The plunger 9 reciprocates in the cylinder 6, sucks fuel into the fuel pressure increasing chamber 10, pressurizes and discharges the fuel from the discharge passage 3 to the outside. An oil hammer runs through the suction passage 2 every time the suction operation is performed, and the pressure of the fuel is pulsating. This pulsation causes a problem in that the amount of outflow of the high-pressure fuel pump 100 is reduced, and the feed-side fuel pipe connected to the suction passage 2 vibrates to generate noise.
[0012]
A pulsation damper 22 having a metal bellows 22a therein is provided in the middle of the suction passage 2. The pulsation damper 22 expands and contracts the metal bellows 22 a in accordance with the fluctuation of the fuel pressure, and absorbs the pulsation of the fuel pressure generated by the high-pressure fuel pump 100. That is, the fuel supplied through the suction passage 2a enters the volume chamber 22b, and then travels to the fuel booster chamber 10 through the suction passage 2b, but the fuel pressure in the suction passage 2b is Pulsating due to suction and discharge operation. At this time, the pulsation damper 22 moves the bellows 22a leftward in FIG. 5 when the fuel pressure is high, and moves the bellows 22a rightward in FIG. 5 when the fuel pressure is low. Thus, the pulsation of the fuel pressure in the suction passage 2 is absorbed.
[0013]
[Problems to be solved by the invention]
However, the fuel pressure pulsation generated by the high-pressure fuel pump 100 did not completely disappear even if the pulsation damper 22 was provided. The pulsation that could not be eliminated spread to a feed-side fuel pipe (not shown) connected to the suction passage 2. The feed-side fuel pipe extends across the vehicle body to the fuel tank, but pulsation that has spread to the feed-side fuel pipe causes a problem because it causes the feed-side fuel pipe to resonate and generate noise.
[0014]
Further, in the conventional high-pressure fuel pump 100 having such a configuration, the fuel leaked from the fuel booster chamber 10 accumulates in the trapping space 16 and returns to the fuel tank through the drain 4. Since the pressure becomes very high at the time of compression, the amount of leaking fuel is a problem.
[0015]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and it is possible to reduce the amount of fuel returning to a fuel tank, and to connect a fuel pressure pulsation generated by a high-pressure fuel pump to a suction passage. It is an object of the present invention to obtain a high-pressure fuel pump for in-cylinder injection that does not spread to a feed-side fuel pipe.
[0016]
[Means for Solving the Problems]
In a high pressure fuel pump for in-cylinder injection according to the present invention, a casing having a suction passage for sucking fuel and a discharge passage for discharging fuel, a cylinder provided in the casing, and a part of the cylinder are formed. fuel Booster chamber, and slidably it has disposed the plunger into the cylinder, by the reciprocating movement of the plunger, inlet pressurized fuel from the suction passage into the fuel Booster chamber, pressure A high pressure fuel pump that discharges the fuel from the discharge passage and pressure-feeds the fuel to the fuel injector of the in-cylinder injection engine, and a recovery groove formed over the entire circumference at an intermediate position of the sliding surface of the cylinder; A communication passage for communicating the recovery groove with the suction passage; a low-pressure pulsation absorption device is provided in the suction passage; and the communication device is provided upstream of the low-pressure pulsation absorption device. Optionally through the suction passage, the first orifice is provided in the suction passage.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment 1 FIG.
FIG. 1 is a side view showing a part of a high-pressure fuel pump for in-cylinder injection according to the present invention in section. In FIG. 1, a suction passage 2, a discharge passage 3, and a drain 4 are formed in a casing 1 of a high-pressure fuel supply pump 200. The suction passage 2 communicates with a feed-side fuel pipe (not shown) extending from the low-pressure fuel pump. On the other hand, the discharge passage 3 communicates with a high-pressure side fuel pipe (not shown) leading to the fuel injector. The drain 4 communicates with a fuel tank (not shown).
[0023]
A cylindrical storage recess 1a is formed below the casing 1 in FIG. A cylinder 36 is provided in the storage recess 1a. The cylinder 36 includes a cylindrical portion 36a and a thick portion 36b provided on one side of the cylindrical portion 36a, and has a cylindrical sliding hole 36c formed along the central axis. The cylinder 36 is disposed with the thick portion 36b side directed toward the bottom 1b of the storage recess 1a.
[0024]
The reed valve 8 is sandwiched between two plates sandwiched between the bottom 1b and the cylinder 36. The reed valve 8 is provided with a suction valve and a discharge valve (not shown) at positions corresponding to the suction passage 2 and the discharge passage 3. Further, a return hole 4 a is provided at a position corresponding to the drain 4.
[0025]
In the sliding hole 36c of the cylinder 36, a substantially cylindrical plunger 9 is disposed so as to be able to reciprocate. The plunger 9 forms the fuel pressure increasing chamber 10 together with the sliding hole 36c. A compression coil spring 11 is housed in the fuel booster chamber 10 in a contracted state. An annular recovery groove 37 is formed at an intermediate position of the sliding hole 36c of the cylinder 36 and formed over the entire circumference.
[0026]
A holder 13 is fixed to an end of the plunger 9 opposite to the fuel pressure increasing chamber 10. A metal bellows 14 is disposed between the thick portion 36 b of the cylinder 36 and the holder 13. The bellows 14 forms a capture space 16 that stores therein fuel leaked from between the plunger 9 and the cylinder 36. The drain 4 returns the fuel extending from the capture space 16 and accumulated in the capture space 16 to a fuel tank (not shown).
[0027]
A cylindrical tappet 18 with a bottom is in contact with the end of the plunger 9 on the side opposite to the fuel pressure increasing chamber 10. The tappet 18 has a cam roller 18a inside. A compression coil spring 19 is contracted between the thick portion 36b and the tappet 18.
[0028]
A bracket 20 is provided around the compression coil spring 19. The bracket 20 has a substantially cylindrical shape having a flange portion 20a at an intermediate portion. The bracket 20 fixes the cylinder 36 to the casing 1 by fastening the flange portion 20a to the casing 1 with a bolt (not shown) and pressing the thick portion 36b at one end.
[0029]
A pulsation damper 22, which is a low-pressure side pulsation absorbing device having a metal bellows 22a therein, is provided in the middle of the suction passage 2. The pulsation damper 22 expands and contracts the metal bellows 22 a in accordance with the fluctuation of the fuel pressure, and absorbs the pulsation of the fuel pressure generated by the high-pressure fuel pump 200. That is, the fuel supplied through the suction passage 2a, which is the suction passage 2 upstream of the pulsation damper 22, enters the volume chamber 22b, and thereafter, the suction passage which is the suction passage 2 downstream of the pulsation damper 22. The fuel pressure in the suction passage 2 is pulsated by the suction operation of the high-pressure fuel pump 200, although the fuel pressure is directed to the fuel pressure increasing chamber 10 through 2 b. At this time, the pulsation damper 22 moves the bellows 22a to the left in FIG. 1 when the fuel pressure is high, and moves the bellows 22a to the right in FIG. 1 when the fuel pressure is low. Thus, the pulsation of the fuel pressure in the suction passage 2 is absorbed.
[0030]
The collection groove 37 formed in the cylinder 36 is connected to the suction passage 2 a upstream of the pulsation damper 22 by a first communication passage 38. Thus, the pressure in the recovery groove 37 is about 3 k, which is the same as the pressure in the suction passage 2a. Conventionally, the pressure in the fuel booster chamber 10 reaches approximately 50 k, while the pressure in the trapping space 16 is almost 0 k, so that the fuel leaks from the fuel booster chamber 10 toward the trapping space 16. When a low-pressure portion of about 3 k is provided in the middle of the moving surface, the fuel accumulates in the recovery groove 37 and does not leak much into the capture space 16. The fuel accumulated in the recovery groove 37 returns to the suction passage 2a through the first communication passage 38, and returns to the fuel pressure increasing chamber 10.
[0031]
On the other hand, when pulsation occurs in the suction passage 2a, the high pressure in the suction passage 2a passes through the first communication passage 38, the trapping space 16, and the drain 4 to a fuel tank (not shown). Therefore, pulsation is reduced.
[0032]
In the high pressure fuel pump for in-cylinder injection configured as described above, the recovery groove 37 is formed at an intermediate position between the sliding holes 36c of the cylinder 36, and the recovery groove 37 is formed in the suction passage 2a by the first communication passage 38. Because of the communication, fuel leakage from the sliding surface between the cylinder 36 and the plunger 9 is reduced. Further, the pulsation of the fuel pressure generated by the high-pressure fuel pump 200 is reduced from propagating upstream of the suction passage 2a, and is less likely to spread to the feed-side fuel pipe connected to the suction passage 2a. Then, noise generated in the feed-side fuel pipe is reduced.
[0033]
In the low-pressure side pulsation absorbing device, not only the pulsation damper 22 having the metal bellows 22a but also a piston-type damper, for example, may be used.
[0034]
Embodiment 2 FIG.
FIG. 2 is a partial cross-sectional side view showing another example of the high pressure fuel pump for in-cylinder injection of the present invention. In the high-pressure fuel pump 201 of the present embodiment, a first orifice 40 is formed in the suction passage 2a upstream of a portion where the first communication passage 38 is connected to the suction passage 2a. Other configurations are the same as those of the first embodiment.
[0035]
In the in-cylinder high pressure fuel pump having such a configuration, when the high pressure fuel pump 201 sucks the fuel from the suction passage 2, the fuel is supplied through the pulsation damper 22. At this time, when the orifice 40 is provided in the suction passage 2a upstream of the pulsation damper 22 as in the present embodiment, the gas flows into the high-pressure fuel pump 201 through the suction passage as compared with the case without the orifice 40. The temporal variation (flow rate pulsation) of the fuel flow rate is reduced. Since the absorbed flow pulsation is reduced by the change in the volume of the pulsation damper 22, the amount of suction into the pressure increasing chamber is the same as when the orifice 40 is not provided. That is, the movement of the pulsation damper 22 can be increased by adding the orifice 40. And the same effect as providing a large-shaped pulsation damper can be obtained.
[0036]
Accordingly, the pulsation of the fuel pressure can be absorbed without providing a large-sized pulsation damper, the size can be reduced, and the vibration of the feed-side fuel pipe can be reduced.
[0037]
Embodiment 3 FIG.
FIG. 3 is a side view partially in section showing another example of the in-cylinder high-pressure fuel pump of the present invention. In the high-pressure fuel pump 202 of the present embodiment, the recovery groove 37 is connected to the suction passage 2b immediately before the reed valve 8 by the second communication passage 41. A first orifice 40 is formed in the suction passage 2a. Other configurations are the same as those of the first embodiment.
[0038]
In the high pressure fuel pump for in-cylinder injection having such a configuration, the surge pressure generated immediately before the fuel booster chamber 10 can be reduced, and pulsation can be effectively reduced.
[0039]
Embodiment 4 FIG.
FIG. 4 is a side view partially in section showing another example of the in-cylinder high-pressure fuel pump of the present invention. In the high-pressure fuel pump 203 of the present embodiment, the recovery groove 37 formed in the cylinder 36 is communicated by the first communication passage 38 to the suction passage 2a upstream of the pulsation damper 22, and further to the second communication The passage 41 communicates with the suction passage 2 b immediately before the reed valve 8. A first orifice 40 is formed in the suction passage 2a between the connection point between the first communication passage 38 and the suction passage 2a and the pulsation damper 22, and the first orifice 40 is formed in the first communication passage 38. A second orifice 42 having a smaller flow path is provided. Other configurations are the same as those of the first embodiment.
[0040]
Since the first communication passage 38 is communicated with the suction passage 2a upstream of the pulsation damper 22, the propagation of fuel pulsation from the pulsation damper 22 to the suction passage further upstream can be suppressed. Further, since the second communication passage 41 is communicated with the suction passage 2b immediately before the reed valve 8, the surge pressure generated immediately before the fuel pressure increasing chamber 10 can be reduced. Then, the first orifice 40 provided in the suction passage 2a can reduce the vibration of the feed-side fuel pipe.
[0041]
On the other hand, due to the first orifice 40, there is a concern that the pressure loss becomes large and the supply of fuel is insufficient, especially when the engine is rotating at a high flow rate, but this is supplemented by the provision of the first communication passage 38. However, if the first communication passage 38 is too large, a large amount of fuel will be supplied from the first communication passage 38 and the effect of the pulsation damper 22 will be weakened. A second orifice 42 having a smaller flow path is provided.
[0042]
In the high pressure fuel pump for in-cylinder injection having such a configuration, it is possible to prevent the pulsation of the fuel from propagating from the pulsation damper 22 to the suction passage further upstream, and to generate the pulsation immediately before the fuel pressure increasing chamber 10. The surge pressure can be reduced, the pulsation can be effectively reduced, and the fuel supply shortage at the time of high rotation can be compensated.
[0043]
At the position where the first orifice 40 is formed, the same effect can be obtained even in the suction passage 2a further upstream from the connection point between the first communication passage 38 and the suction passage 2a.
[0044]
【The invention's effect】
In the high pressure fuel pump for in-cylinder injection according to the present invention, a casing having a suction passage for sucking fuel and a discharge passage for discharging fuel, a cylinder provided in the casing, and a part of the cylinder are formed. fuel Booster chamber, and slidably it has disposed the plunger into the cylinder, by the reciprocating movement of the plunger, inlet pressurized fuel from the suction passage into the fuel Booster chamber, pressure A high pressure fuel pump that discharges the fuel from the discharge passage and pressure-feeds the fuel to the fuel injector of the in-cylinder injection engine, and a recovery groove formed over the entire circumference at an intermediate position of the sliding surface of the cylinder; A communication passage for communicating the recovery groove with the suction passage; and a low-pressure pulsation absorption device provided in the middle of the suction passage, wherein the communication device is provided upstream of the low-pressure pulsation absorption device. Optionally through the suction passage, the first orifice is provided in the suction passage. Therefore, pulsation can be absorbed without providing a large-sized accumulator, and vibration of the feed-side fuel pipe can be reduced. The provision of the second communication passage can reduce the surge pressure and compensate for the shortage of fuel supply at the time of high rotation, and the provision of the second orifice does not excessively weaken the effect of the low-pressure side pulsation absorber. .
[Brief description of the drawings]
FIG. 1 is a side view showing a part of a high-pressure fuel pump for in-cylinder injection of the present invention in section.
FIG. 2 is a side view partially in section showing another example of the in-cylinder high-pressure fuel pump of the present invention.
FIG. 3 is a side view partially in section showing another example of the high pressure fuel pump for in-cylinder injection of the present invention.
FIG. 4 is a partial cross-sectional side view showing another example of the in-cylinder injection high-pressure fuel pump of the present invention.
FIG. 5 is a side view showing a part of a conventional high pressure fuel pump for in-cylinder injection in section.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 casing, 2 suction passage, 3 discharge passage, 6 cylinder, 9 plunger, 10 fuel booster chamber, 22 pulsation damper (low pressure side pulsation absorber), 37 recovery groove, 38 first communication passage (communication passage), 40 first orifice, 41 second communication passage (communication passage), 42 second orifice.

Claims (3)

A casing in which a suction passage for sucking fuel and a discharge passage for discharging fuel are formed, a cylinder provided in the casing, a fuel booster chamber formed in a part of the cylinder, and slidable in the cylinder The plunger is disposed in the cylinder, and by reciprocating the plunger, fuel is sucked and pressurized from the suction passage into the fuel booster chamber, and the pressurized fuel is discharged from the discharge passage to in-cylinder injection type. A high-pressure fuel pump for pressure-feeding the fuel to an engine fuel injector, comprising: a recovery groove formed over the entire circumference at an intermediate position of a sliding surface of the cylinder; and a communication passage communicating the recovery groove and the suction passage. Prepare,
A low pressure side pulsation absorber is provided in the middle of the suction passage, and the communication device communicates with the suction passage upstream of the low pressure side pulsation absorber, and a first orifice is provided in the suction passage. A high-pressure fuel pump for in-cylinder injection. A casing in which a suction passage for sucking fuel and a discharge passage for discharging fuel are formed, a cylinder provided in the casing, a fuel booster chamber formed in a part of the cylinder, and slidable in the cylinder The plunger is disposed in the cylinder, and by reciprocating the plunger, fuel is sucked and pressurized from the suction passage into the fuel booster chamber, and the pressurized fuel is discharged from the discharge passage to in-cylinder injection type. A high-pressure fuel pump for pressure-feeding the fuel to an engine fuel injector, comprising: a recovery groove formed over the entire circumference at an intermediate position of a sliding surface of the cylinder; and a communication passage communicating the recovery groove and the suction passage. Prepare,
A low-pressure-side pulsation absorbing device is provided in the middle of the suction passage; the communication passage includes a first communication passage for communicating the recovery groove with the suction passage upstream of the low-pressure pulsation absorbing device; A high-pressure fuel pump for in-cylinder injection, comprising: a second communication passage that communicates with the suction passage immediately before the fuel pressure boosting chamber. A first orifice is provided in the suction passage upstream of the low-pressure side pulsation absorber, and a second orifice having a smaller flow path than the first orifice is provided in the first communication passage. The high-pressure fuel pump for in-cylinder injection according to claim 2, characterized in that:

Images