JP3875441B2 - High pressure fuel pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-pressure fuel pump used in, for example, a cylinder injection engine.
[0002]
[Prior art]
3 is a circuit diagram of a fuel supply apparatus including a conventional high-pressure fuel supply apparatus 100, FIG. 4 is an overall cross-sectional view of the high-pressure fuel supply apparatus 100 cut out, and FIG. 5 is a cross-sectional view of the valve of FIG. is there.
The high-pressure fuel supply device 100 is provided in the low-pressure fuel intake passage 3 and absorbs the pulsation of the low-pressure fuel, and the high-pressure fuel pump that pressurizes the low-pressure fuel from the low-pressure damper 5 and discharges it to the high-pressure fuel discharge passage 7. 6, a high-pressure damper 8 that absorbs pulsation of high-pressure fuel flowing in the high-pressure fuel discharge passage 7, and a branch passage 9 that is branched from the high-pressure fuel discharge passage 7 by a branch portion 18, and adjusts the high-pressure fuel to a predetermined pressure. The high pressure regulator 10 which presses and the orifice 11 provided in the high pressure fuel discharge passage 7 between the high pressure damper 8 and the branch part 18 are provided.
In the vicinity of the high-pressure fuel supply device 100, a low-pressure fuel is provided at a constant pressure by being provided in the fuel tank 1, the low-pressure fuel pump 2 in the fuel tank 1, and the low-pressure fuel intake passage 3 through which the low-pressure fuel from the low-pressure fuel pump 2 flows. A low-pressure regulator 4, a filter 12, and a drain pipe 17 that connects the high-pressure regulator 10 and the fuel tank 1 are provided.
[0003]
The high-pressure fuel pump 6 includes a valve 20 that opens and closes the low-pressure fuel intake passage 3 and the high-pressure fuel discharge passage 7, and a high-pressure fuel supply that pressurizes low-pressure fuel from the low-pressure fuel intake passage 3 and discharges it to the high-pressure fuel discharge passage 7. And a body 21.
The valve 20 includes a first plate 22 and a second plate 23, and a thin plate-like valve body 19 sandwiched between the plates 22 and 23. The first plate 22 communicates with the high pressure fuel discharge passage 7 with a first fuel intake port 24 communicating with the low pressure fuel intake passage 3 and with an internal dimension larger than the internal dimension of the first fuel intake port 24. The fuel discharge port 25 is formed. The second plate 23 is formed with a second fuel inlet 26 having a larger inner dimension than the first fuel inlet 24 and a second fuel outlet 27 having a smaller inner dimension than the first fuel outlet 25. Has been. The valve body 19 includes a suction side piece 28 interposed between the first fuel suction port 24 and the second fuel suction port 26, and the first fuel discharge port 25 and the second fuel discharge port 27. An intervening discharge side piece 29 is provided.
[0004]
The high-pressure fuel supply body 21 includes a casing 30 in which the valve 20 is accommodated in a first recess 30 a, a cylindrical sleeve 31 that is accommodated in surface contact with the second plate 23 of the valve 20, and an inside of the sleeve 31. Between the piston 33, which is slidably inserted into the sleeve 31 and forms the fuel pressurizing chamber 32 in cooperation with the sleeve 31, and the bottom surface 34 of the fuel pressurizing chamber 32 and the holder 35. And a first spring 36 that urges the piston 33 in the expanding direction.
Further, the high pressure fuel supply body 21 includes a housing 37 in which a sleeve 31 is fitted on the inner peripheral surface, and a male screw portion 38 a that is fitted on the housing 37 on the inner peripheral surface and formed on the outer peripheral surface. A ring-shaped fastening member 38 that is screwed into the first recess 30 a and presses and fixes the valve 20, the sleeve 31, and the housing 37 in the first recess 30 a of the casing 30, and between the housing 37 and the receiving portion 39. A metal bellows 40 provided on the outer periphery of the bellows 40, a second spring 41 contracted between the housing 37 and the holder 42 on the outer periphery of the bellows 40, and a casing 30 provided around the second spring 41. And a bracket 43 fixed with screws (not shown).
[0005]
The high-pressure fuel supply body 21 has a tappet 44 slidably provided in a sliding hole 43 a at the end of the bracket 43, a pin 45 that passes through the tappet 44 in a freely rotatable manner, and the pin 45 is freely rotatable. Are provided with a bush 46 and a cam roller 47, respectively. The rotational movement of the camshaft causes the pin 45, tappet 44 and piston 33 to reciprocate according to the profile of the cam 50.
[0006]
The high-pressure damper 8 includes a diaphragm (not shown) made of a thin disc stainless steel that is divided into a back pressure chamber (not shown) and a buffer chamber (not shown) filled with high-pressure gas. This diaphragm moves so that the pressure of the fuel flowing into the buffer chamber from the high-pressure fuel discharge passage 7 and the pressure of the high-pressure gas in the back pressure chamber are balanced, whereby the volume in the buffer chamber is changed and the high-pressure fuel is changed. The pulsation of the fuel in the discharge passage 7 is absorbed.
[0007]
In the high-pressure fuel supply apparatus 100 configured as described above, the piston 33 reciprocates via the cam roller 47, the bush 46, the pin 45, and the tappet 44 by the rotation of the cam 50 fixed to the cam shaft of the engine.
When the piston 33 descends (during the fuel intake stroke), the volume in the fuel pressurizing chamber 32 increases and the pressure in the fuel pressurizing chamber 32 is reduced. When the pressure in the fuel pressurizing chamber 32 becomes lower than the pressure in the first fuel inlet 24, the suction side piece 28 of the valve body 19 is bent and deformed toward the second fuel inlet 26, and the pressure in the low pressure fuel supply passage 3 is increased. The fuel flows into the fuel pressurizing chamber 32 through the first fuel inlet 24.
When the piston 33 rises (during the fuel discharge stroke), the pressure inside the fuel pressurization chamber 32 is increased, and when the pressure in the fuel pressurization chamber 32 becomes higher than the pressure in the first fuel discharge port 25, The discharge side piece 29 is bent and deformed to the first fuel discharge port 25, and the fuel in the fuel pressurizing chamber 32 is sent to the high pressure damper 8 through the first fuel discharge port 25 and the fuel discharge passage 7, where fuel pressure pulsation is generated. Is absorbed. Fuel pressure pulsation of the high-pressure fuel is absorbed by an orifice 11 provided downstream of the high-pressure damper 8. The high-pressure fuel in which the pulsation is absorbed is supplied into the delivery pipe 13 through the high-pressure pipe 16 and then supplied through the fuel injection valve 14 to each cylinder of the engine (not shown).
[0008]
In the high-pressure fuel pump 6 having the above-described configuration, the fastening member 38 is screwed into the first recess 30a of the casing 30 by the male screw portion 38a formed on the outer peripheral surface. The valve 20, the sleeve 31, and the housing 37 are pressed and fixed in the first recess 30a. A flat washer 200 is interposed between the housing 37 and the fastening member 38. As can be seen from the enlarged view of the portion of FIG. 4, the flat washer 200 is disposed on the inner diameter side of the fastening member 38 so that a large load is applied to the central portion of the valve 20. In other words, the fuel inlets 24 and 26 and the fuel outlets 25 and 27 of the valve 20 are on the inner diameter side of the valve 20, and the force that sandwiches the first plate 22 and the second plate 23 with respect to the valve body 19 in the vicinity thereof. As a result, the discharge flow rate is prevented from decreasing due to the occurrence of fretting of the valve main body 19, the first plate 22, and the second plate 23.
[0009]
[Problems to be solved by the invention]
In the high-pressure fuel pump 6 configured as described above, the flat washer 200 is disposed on the inner diameter side of the fastening member 38. However, when the fastening member 38 is fastened, the axial force (the fastening member 38 of the fastening member 38) Due to the force acting in the axial direction, a bending moment is generated in the fastening member 38 in the direction of arrow C with the outer peripheral portion A of the plain washer 200 as a fulcrum. The value of the bending moment is a large value because the distance between the outer peripheral portion A of the flat washer 200 and the screw portion 38a is long. When the rigidity of the fastening member 38 itself is insufficient, the fastening member 38 is deformed in the direction of arrow C, and this deformation causes the rotation angle of the fastening member 38 (from the time when the front end surface of the fastening member 38 abuts against the flat washer 200). The axial force with respect to the amount of movement in the axial direction is reduced. The reduction of the axial force due to the deformation of the fastening member 38 leads to the initial loosening of the fastening member 38 during the initial operation of the high-pressure fuel supply device 100, and the valve body 19, the first plate 22, and the second plate. 23 has a problem that fretting occurs and the discharge flow rate decreases, and the tendency is particularly remarkable at high temperatures where the viscosity of the fuel decreases.
[0010]
An object of the present invention is to solve such a problem, in which a decrease in axial force due to deformation of the fastening member is suppressed, and the valve main body, the first plate, and the second plate An object of the present invention is to obtain a high-pressure fuel pump that can prevent occurrence of fretting and secure a predetermined discharge flow rate.
[0011]
[Means for Solving the Problems]
In the high pressure fuel pump according to claim 1 of the present invention, a washer is disposed between the housing and the fastening member so as to be biased toward the outer diameter side of the fastening member, and a gap is provided between the washer and the casing. Thus, the bending moment of the fastening member, which is generated by the axial force of the fastening member and has the outer periphery of the washer as a fulcrum, is small.
[0012]
In the high pressure fuel pump according to claim 2 of the present invention, a step portion for positioning the washer is formed on the outer peripheral portion of the housing.
[0013]
In the high pressure fuel pump according to claim 3 of the present invention, a recess for positioning the washer is formed on the outer diameter side of the fastening member.
[0014]
In the high pressure fuel pump according to claim 4 of the present invention, the outer peripheral side surface of the washer is in contact with the concave portion of the casing.
[0015]
In the high pressure fuel pump according to claim 5 of the present invention, the washer is a flat washer.
[0016]
In the high pressure fuel pump according to claim 6 of the present invention, the washer is made of copper.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
Hereinafter, the high-pressure fuel pump of the present invention will be described. FIG. 1 is a partially cutaway cross-sectional view of a high-pressure fuel supply apparatus 300 in which the high-pressure fuel pump 301 is incorporated. The same or corresponding parts as those shown in FIGS. To do.
The high-pressure fuel supply device 300 is provided in the low-pressure fuel intake passage 3 and absorbs the pulsation of the low-pressure fuel, and the high-pressure fuel pump that pressurizes the low-pressure fuel from the low-pressure damper 5 and discharges it to the high-pressure fuel discharge passage 7. 301, a high-pressure damper 8 that absorbs pulsation of high-pressure fuel flowing in the high-pressure fuel discharge passage 7, and a branch passage 9 that is branched from the high-pressure fuel discharge passage 7 by a branch portion 18, adjusts the high-pressure fuel to a predetermined pressure. A high-pressure regulator 10 that presses and a high-pressure damper 8 are provided.
[0018]
The high-pressure fuel pump 301 includes a valve 20 for opening and closing the low-pressure fuel intake passage 3 and the high-pressure fuel discharge passage 7, and a high-pressure fuel supply that pressurizes low-pressure fuel from the low-pressure fuel intake passage 3 and discharges it to the high-pressure fuel discharge passage 7. And a body 21.
The valve 20 includes a first plate 22 and a second plate 23, and a thin plate-like valve body 19 sandwiched between the plates 22 and 23. The first plate 22 communicates with the high pressure fuel discharge passage 7 with a first fuel intake port 24 communicating with the low pressure fuel intake passage 3 and with an internal dimension larger than the internal dimension of the first fuel intake port 24. The fuel discharge port 25 is formed. The second plate 23 is formed with a second fuel inlet 26 having a larger inner dimension than the first fuel inlet 24 and a second fuel outlet 27 having a smaller inner dimension than the first fuel outlet 25. Has been. The valve body 19 includes a suction side piece 28 interposed between the first fuel suction port 24 and the second fuel suction port 26, and the first fuel discharge port 25 and the second fuel discharge port 27. An intervening discharge side piece 29 is provided.
[0019]
The high-pressure fuel supply body 21 includes a casing 30 in which the valve 20 is accommodated in a first recess 30 a, a cylindrical sleeve 31 that is accommodated in surface contact with the second plate 23 of the valve 20, and an inside of the sleeve 31. The piston 33 slidably inserted in the sleeve 31 and cooperates with the sleeve 31 to form the fuel pressurizing chamber 32, and is sandwiched between the bottom surface 34 of the fuel pressurizing chamber 32 and the holder 35. And a first spring 36 that urges the piston 33 in the expanding direction.
The high-pressure fuel supply body 21 includes a housing 137 in which a sleeve 31 is fitted on the inner peripheral surface, and a male screw portion 38 a that is fitted on the housing 37 on the inner peripheral surface and formed on the outer peripheral surface. A ring-shaped fastening member 38 that is screwed into the female thread 30b of the first recess 30a and presses and fixes the valve 20, the sleeve 31, and the housing 137 into the first recess 30a of the casing 30, and the housing 137 A metal bellows 40 provided between the portion 39, a second spring 41 contracted between the housing 137 and the holder 42 on the outer periphery of the bellows 40, and the second spring 41. And a bracket 43 which is provided and fixed to the casing 30 with screws (not shown).
[0020]
The high-pressure fuel supply body 21 has a tappet 44 slidably provided in a sliding hole 43 a at the end of the bracket 43, a pin 45 that passes through the tappet 44 in a freely rotatable manner, and the pin 45 is freely rotatable. Are provided with a bush 46 and a cam roller 47, respectively. The rotational movement of the camshaft causes the pin 45, tappet 44 and piston 33 to reciprocate according to the profile of the cam 50.
[0021]
In the high-pressure fuel supply apparatus 300 having the above-described configuration, the piston 33 reciprocates via the cam roller 47, the bush 46, the pin 45, and the tappet 44 by the rotation of the cam 50 fixed to the camshaft of the engine.
When the piston 33 descends (during the fuel intake stroke), the volume in the fuel pressurizing chamber 32 increases and the pressure in the fuel pressurizing chamber 32 is reduced. When the pressure in the fuel pressurizing chamber 32 becomes lower than the pressure in the first fuel inlet 24, the suction side piece 28 of the valve body 19 is bent and deformed toward the second fuel inlet 26, and the pressure in the low pressure fuel supply passage 3 is increased. The fuel flows into the fuel pressurizing chamber 32 through the first fuel inlet 24.
When the piston 33 rises (during the fuel discharge stroke), the pressure inside the fuel pressurization chamber 32 is increased, and when the pressure in the fuel pressurization chamber 32 becomes higher than the pressure in the first fuel discharge port 25, The discharge side piece 29 is bent and deformed to the first fuel discharge port 25, and the fuel in the fuel pressurizing chamber 32 is sent to the high pressure damper 8 through the first fuel discharge port 25 and the fuel discharge passage 7, where fuel pressure pulsation is generated. Is absorbed. Fuel pressure pulsation of the high-pressure fuel is absorbed by an orifice 11 provided downstream of the high-pressure damper 8. The high-pressure fuel in which the pulsation is absorbed is supplied into the delivery pipe 13 through the high-pressure pipe 16 and then supplied through the fuel injection valve 14 to each cylinder of the engine (not shown).
[0022]
In the high-pressure fuel pump 301 having the above-described configuration, the fastening member 38 is screwed to the female screw portion 30b of the first recess 30a of the casing 30 with the male screw portion 38a formed on the outer peripheral surface. 38, the valve 20, the sleeve 31, and the housing 137 are pressed and fixed in the first recess 30a of the casing 30. As can be seen from the enlarged view of the portion in FIG. 1, a flat washer 51 is disposed on the outer diameter side of the fastening member 38 between the housing 137 and the fastening member 38. The ring-shaped plain washer 51 is positioned by a step 53 formed on the outer peripheral edge of the housing 137.
In addition, you may make it form the recessed part which positions the plain washer 51 in the outer-diameter side of the front end surface of a fastening member.
[0023]
A bending moment is generated in the fastening member 38 in the direction of the arrow F with the outer peripheral portion D of the plain washer 51 as a fulcrum by the axial force indicated by the arrow E of the fastening member 38 itself. The value of the bending moment is small because the distance between the outer peripheral portion D of the flat washer 51 and the screw portion 38a is shorter than that of the conventional one. Therefore, deformation of the fastening member 38 itself in the direction of arrow F is suppressed, the axial force generated with respect to the rotation angle of the fastening member 38 increases, and the screw of the fastening member 38 during the initial operation of the high-pressure fuel supply device 300 Initial loosening can be suppressed, and occurrence of fretting in the valve main body 19, the first plate 22, and the second plate 23 can be suppressed.
[0024]
In the high-pressure fuel pump 301 according to the first embodiment, the load applied to the central portion of the valve 20 is smaller than that of the conventional high-pressure fuel pump 6 in which the plain washer 200 is disposed on the inner diameter side of the fastening member 38, and from this point Considering this, although the effect of suppressing the occurrence of fretting in the valve main body 19, the first plate 22 and the second plate 23 is reduced, the generated axial force due to the suppression of the deformation due to the bending moment of the fastening member 38 is suppressed. The effect of suppressing the occurrence of fretting in the valve main body 19, the first plate 22 and the second plate 23 due to the increase is great, and the initial screw loosening of the fastening member 38 during initial operation can be suppressed. it can.
According to the experiment by the present inventor, for example, in the conventional high-pressure fuel pump 6, the internal fuel pressure capable of securing a predetermined discharge flow rate was 7 MPa, whereas in the first embodiment, the internal fuel pressure was up to 10 MPa. It was possible to respond.
[0025]
As a method of suppressing the deformation of the fastening member 38, the rigidity of the fastening member 38 can be increased, that is, the radial dimension of the fastening member 38 can be increased. Although it is necessary to change the shape significantly, in the first embodiment, it is not necessary to change those components.
Further, the plain washer 51 is made of copper, has a lower proof strength than the fastening member 38 and the housing 137, and can prevent local contact with the housing 137 due to the inclination of the fastening member 38 by plastic deformation, The axial force of the fastening member 38 can be stabilized.
[0026]
Embodiment 2. FIG.
FIG. 2 is a cross-sectional view of a main part of the high-pressure fuel pump 301 according to the second embodiment.
In the second embodiment, the width of the copper-made ring-shaped flat washer 54 is increased to a position where it partially abuts on the female screw portion 30 b of the casing 30.
In the first embodiment, the step portion 53 must be formed in the housing 137 for positioning the flat washer 51. However, in the second embodiment, the conventional housing 37 does not need to be processed.
Before the fastening member 38 is fastened, there is a gap between the outer peripheral side surface of the flat washer 54 and the female screw portion 30b, and the washer 54 prevents the fastening member 38 from moving in the axial direction when the fastening member 38 is fastened. There is no such thing.
[0027]
【The invention's effect】
As described above, according to the high pressure fuel pump according to the first aspect of the present invention, the washer is disposed between the housing and the fastening member so as to be biased toward the outer diameter side of the fastening member, and the axial force of the fastening member is used. As a result, the bending moment of the fastening member with the outer periphery of the washer as a fulcrum is small, so that a reduction in axial force due to deformation due to the bending moment of the fastening member can be suppressed. As a result, the valve body, the first plate and the first plate It is possible to prevent the occurrence of fretting on the plate 2 and to secure a predetermined discharge flow rate. In particular, the discharge flow rate is secured at a high temperature at which the viscosity of the fuel decreases, and the initial operation of the high-pressure fuel pump The initial screw loosening of the fastening member can be suppressed.
Further, since there is a gap between the washer and the casing, even if the washer that receives the axial force is deformed by tightening the fastening member, the deformation of the washer is not hindered by the gap, and the fastening member is tightened. The axial force due to is more stably transmitted to the valve, the sleeve and the housing.
[0028]
According to the high pressure fuel pump of the present invention, since the step portion for positioning the washer is formed on the outer peripheral portion of the housing, the washer is easily positioned at a predetermined position.
[0029]
According to the third aspect of the present invention, since the recess for positioning the washer is formed on the outer diameter side of the fastening member, the washer can be easily positioned at a predetermined position.
[0030]
According to the high pressure fuel pump of claim 4 of the present invention, the washer is positioned by contacting the outer peripheral side surface with the concave portion of the casing, and it is not necessary to bother processing the housing and the fastening member for positioning. .
[0031]
In the high pressure fuel pump according to claim 5 of the present invention, since the washer is a flat washer, the axial force transmission path from the fastening member to the housing is large, and a stable axial force is transmitted from the fastening member to the housing. The
[0032]
According to the high pressure fuel pump of claim 6 of the present invention, since the washer is made of copper, the cost is low, and the washer is plastically deformed in the radial direction by the axial force from the fastening member. A stable axial force is transmitted to the housing.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a high-pressure fuel pump according to Embodiment 1 of the present invention.
FIG. 2 is a cross-sectional view of a main part of a high-pressure fuel pump according to a second embodiment of the present invention.
FIG. 3 is a circuit diagram of a conventional high-pressure fuel supply apparatus.
4 is a cross-sectional view of the high-pressure fuel pump of FIG.
5 is a cross-sectional view of a valve of the high-pressure fuel pump of FIG.
[Explanation of symbols]
3 Low-pressure fuel intake passage, 6 High-pressure fuel pump, 7 High-pressure fuel discharge passage, 19 Valve body, 20 Valve, 21 High-pressure fuel supply body, 22 First plate, 23 Second plate, 30 Casing, 31 Sleeve, 32 Fuel Pressurizing chamber, 33 piston, 37, 137 housing, 38 fastening member, 51, 54 washer, 53 steps, 301 high pressure fuel pump.

Claims (5)

A valve that opens and closes a low-pressure fuel intake passage and a high-pressure fuel discharge passage, and a high-pressure fuel supply that pressurizes low-pressure fuel from the low-pressure fuel intake passage and discharges the low-pressure fuel into the high-pressure fuel discharge passage.
The valve is composed of a first plate, a second plate, and a valve body sandwiched between the first plate and the second plate,
The high-pressure fuel supply body includes a casing housing the valve in a recess, a sleeve housed in surface contact with the second plate, and a fuel slidably inserted into the sleeve in cooperation with the sleeve. A piston forming a pressurizing chamber; a housing fitted with the sleeve; and a male screw portion formed on the outer peripheral surface of the housing and screwed into the concave portion of the casing. A high pressure fuel pump including a ring-shaped fastening member that presses and fixes the valve, the sleeve, and the housing in a recess,
Between the housing and the fastening member, a washer is disposed on the outer diameter side of the fastening member, and a gap is provided between the washer and the casing.
A high-pressure fuel pump in which a bending moment of a fastening member, which is generated by an axial force of the fastening member and has an outer peripheral portion of a washer as a fulcrum, is small.   The high-pressure fuel pump according to claim 1, wherein a stepped portion for positioning a washer is formed on an outer peripheral portion of the housing. The high-pressure fuel pump according to claim 1, wherein a recess for positioning the washer is formed on a front end surface of the fastening member. The high pressure fuel pump according to any one of claims 1 to 3 , wherein the washer is a plain washer.   The high pressure fuel pump according to any one of claims 1 to 4, wherein the washer is made of copper.

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