JP5302052B2 - Fuel supply pump - Google Patents

Description

  The present invention relates to a fuel supply pump that pressurizes and pressurizes fuel, and more particularly to a fuel supply pump that is used in an accumulator fuel supply device including a common rail and includes a cam ring that revolves around an eccentric cam portion.

  Conventionally, as a device for supplying fuel to an internal combustion engine such as a diesel engine, a plurality of injectors are connected and a common rail in which high-pressure fuel is stored is provided, and by constantly supplying high-pressure fuel to each injector, Various pressure accumulation fuel supply devices (common rail systems) that enable precise fuel injection control have been proposed.

  FIG. 13 shows an example of the configuration of the fuel supply pump 300 used in such a common rail system. The fuel supply pump 300 includes a camshaft 303 having an eccentric cam portion 301, a cam ring 305 that revolves around the eccentric cam portion 301 as the eccentric cam portion 301 rotates, and the eccentric cam portion 301 and the cam ring 305. And a housing 311 having a shaft hole 311b that rotatably supports the camshaft 303 (see, for example, Patent Document 1).

  In the fuel supply pump 300, the cam ring 305 rotates with the rotation of the camshaft 303 and the eccentric cam portion 301, and the plunger 307 reciprocates to pressurize the fuel in the pressurizing chamber 308. Is pumped toward the common rail.

JP 2003-49745 A (FIGS. 1 and 2)

  In recent years, with the advancement of exhaust gas purification standards, the maximum fuel injection pressure from the accumulator fuel supply device tends to be increased, and the target pressure in the common rail is increasing more than before. When the pressure in the common rail increases, the fuel discharge pressure from the fuel supply pump needs to be increased, and the drive torque of the fuel supply pump tends to increase.

  The driving torque of the fuel supply pump affects the load acting on the camshaft from the plunger. When the driving torque increases, the load acting on the camshaft from the plunger increases. The surface pressure acting on the inner peripheral surface of the shaft hole increases. For this reason, the inner peripheral surface of the shaft hole of the housing and the outer peripheral surface of the camshaft facing the shaft hole are likely to be worn or seized, and the bearing member disposed between the shaft hole and the camshaft is easily damaged. Become.

  As a countermeasure for increasing the pressure against such problems as wear and seizure, the surface pressure acting on the inner peripheral surface of the shaft hole of the housing that supports the camshaft is increased by increasing the diameter of the camshaft support. It is possible to disperse.

However, in the conventional fuel supply pump 300 as shown in FIG. 13, the cam ring 305 or the inner peripheral surface of the cam ring 305 has a diameter of the support portion 302 for the reason of assembling the cam ring 305 to the cam shaft 303. Therefore, in order to increase the diameter of the support portion 302 of the camshaft 303, it is necessary to prepare a bush as a separate member.
On the other hand, if the supporting portion 302 of the camshaft 303 is enlarged and the cam ring 305 is configured in accordance with the diameter of the supporting portion 302, the eccentric cam portion 301 must be enlarged, so the cam chamber 311a and thus the housing 311 are large. Thus, the entire fuel supply pump 300 becomes large.

  These problems will be specifically described with reference to FIGS. 14A to 14D show a view of the camshaft 303 and the cam ring 305 having the eccentric cam portion 301 as viewed from the side, and the cam ring 305 is shown by a cross-sectional view. 14A to 14D, the length of the longest portion of the eccentric cam portion 301 from the rotation axis Ax to the outer peripheral surface is m, the shortest portion is n, and the camshaft 303 is supported. The radius of the portion 303a is represented by r, and the diameter of the cam ring 305 or the opening 305a of the bearing member (not shown) is represented by 2R.

  In order to efficiently transmit the rotational force of the eccentric cam portion 301 to the reciprocating movement of the plunger, there is an excessive gap between the outer peripheral surface of the eccentric cam portion 301 and the inner peripheral surface of the cam ring 305 or the bearing member opening 305a. In general, the cam ring 305 and the eccentric cam portion 301 are designed so that they are not formed. In the example of the conventional camshaft 303 shown in FIG. 14A, the diameter 2R of the opening 305 a of the cam ring 305 is designed to be substantially equal to m + n that is the maximum length of the eccentric cam portion 301.

  Therefore, of the support portions 303 a and 303 b of the camshaft 303, the radius r of the support portion 303 a on the side inserted into the opening 305 a of the cam ring 305 when the cam ring 305 is assembled is at least from the rotational axis Ax in the eccentric cam portion 301. The distance to the outer peripheral surface is smaller than the length n of the shortest part. If the eccentric cam portion 301 and the support portion 303a are not designed in this way, as shown in FIG. 14B, the cam ring 305 having the opening 305a having a diameter 2R is held in front of the eccentric cam portion 301, and the cam ring This is because 305 cannot be disposed around the eccentric cam portion 301.

  In order to increase the diameter 2r of the support portion 303a of the camshaft 303 as a countermeasure against high pressure, for example, the bush 310 can be fixed around the support portion 303a as shown in FIG. In the example of FIG. 14C, the bushing 310 is fixed around the support portion 303 a of the camshaft 303 after the cam ring 305 is arranged around the eccentric cam portion 301. As a result, the diameter 2r ′ of the support portion 303a of the camshaft 303 is substantially increased by the thickness of the bush 310. However, when configured as shown in FIG. 14C, the bush 310 as a separate member must be prepared, which increases the number of parts and leads to an increase in cost.

  On the other hand, when the diameter 2r of the support portion 303a of the camshaft 303 is increased, it is also possible to increase the diameter 2R = m + n of the eccentric cam portion 301 and the opening 305a of the cam ring 305 as shown in FIG. . However, in the case of the configuration as shown in FIG. 14D, the outer shape of the cam ring 305 itself is increased, and the cam chamber for accommodating the cam ring 305 is increased. As a result, the fuel supply pump is increased in size, and there is a concern that the merchantability of the fuel supply pump may decrease, for example, the mountability to an internal combustion engine or a vehicle may decrease.

  Therefore, as a result of intensive studies, the inventors of the present invention have found that such a problem can be solved by configuring the cam ring as a plurality of divided bodies that can be separated in the direction intersecting the rotation axis of the cam shaft, The present invention has been completed. That is, according to the present invention, the diameter of the support portion of the camshaft can be increased without being limited by the size of the opening of the cam ring, and the high pressure durability can be improved while avoiding the enlargement of the fuel supply pump. It is an object to provide a fuel supply pump.

According to the present invention, a plurality of camshafts having an eccentric cam portion and a plurality of camshafts arranged on the outer peripheral side of the eccentric cam portion are reciprocated with the rotation of the eccentric cam portion to pressurize the fuel in the pressurizing chamber. A plunger to be pumped, and a cam ring that is disposed between the eccentric cam portion and the plunger and revolves around the eccentric cam portion around a rotation axis of the cam shaft as the eccentric cam portion rotates. A fuel supply pump comprising a housing having a cam chamber that houses the eccentric cam portion and the cam ring and a shaft hole that rotatably supports the cam shaft, wherein the cam ring includes a rotation shaft of the cam shaft. play portion for Ri do a plurality of divided bodies separable in the direction crossing, each of the divided body is not restricted from moving in the rotational direction of the cam shaft by other divided member It has the play portion may be a fuel supply pump, characterized in that constructed by sandwiching an elastic body between the split body adjacent is provided to solve the problems described above.

  Further, according to another aspect of the present invention, a plurality of camshafts having an eccentric cam portion and a plurality of camshafts arranged on the outer peripheral side of the eccentric cam portion are pressurized by reciprocating as the eccentric cam portion rotates. A plunger that pressurizes and feeds fuel in the room; and the eccentric cam portion that is disposed between the eccentric cam portion and the plunger and that rotates around the rotational axis of the camshaft as the eccentric cam portion rotates. A fuel supply pump comprising a cam ring that revolves around, a housing having a cam chamber that accommodates the eccentric cam portion and the cam ring, and a shaft hole that rotatably supports the cam shaft. It consists of a plurality of divided bodies that can be separated in the direction intersecting the rotation axis of the camshaft, and each of the divided bodies regulates the movement of the camshaft in the rotational direction by the other divided bodies. A plurality of divided bodies are provided with pin insertion holes extending in the direction of the rotation axis of the camshaft and connected to the pin insertion holes. Are inserted and assembled, and the play portion provides a gap between the adjacent divided bodies, and the diameter or width of the pin insertion hole provided in at least one of the adjacent divided bodies. Is provided by making the diameter larger than the diameter of the connecting pin, and the above-described problems can be solved.

  In configuring the fuel supply pump of the present invention, it is preferable that the cam ring is divided corresponding to the plurality of plungers.

  Further, in configuring the fuel supply pump of the present invention, it is preferable that the radius of the cam shaft at the portion supported by the shaft hole of the housing is longer than the shortest distance from the rotating shaft on the outer peripheral surface of the eccentric cam portion.

  Further, when the bearing member is disposed between the eccentric cam portion and the cam ring in configuring the fuel supply pump of the present invention, the bearing member is configured to be separable in a direction intersecting the rotation axis of the cam shaft. It is preferred that

  According to the fuel supply pump of the present invention, since the cam ring is composed of a plurality of divided bodies, the cam ring can be assembled around the eccentric cam portion without inserting the cam shaft into the opening of the cam ring. . Therefore, the diameter of the support portion of the camshaft can be designed large regardless of the size of the opening of the cam ring. As a result, even if the diameter of the support portion of the camshaft is increased, there is no need to increase the eccentric cam portion and the cam ring, and the high pressure durability of the fuel supply pump is improved while avoiding an increase in the size of the fuel supply pump. Is planned.

  In the fuel supply pump of the present invention, the cam ring formed of a plurality of divided bodies includes a predetermined play portion, so that even if one of the divided bodies of the cam ring is inclined due to a load from a certain plunger, Inclination is prevented from being affected, and the contact between the other divided body and the plunger or tappet is reduced. Therefore, the wear of the cam ring is reduced, and the high pressure durability of the fuel supply pump is improved.

  In the fuel supply pump of the present invention, the play portion is easily formed by forming the play portion with a predetermined gap. Further, if there is a gap between the adjacent divided bodies, the lubricating oil can easily flow between the cam ring and the eccentric cam portion.

  Further, in the fuel supply pump of the present invention, the play portion is configured using a predetermined elastic body, so that it functions as a play portion when a load is generated from the plunger, while no load is generated from the plunger. In the state, the position of each divided body is defined.

  In the fuel supply pump of the present invention, the cam ring is assembled using the pin insertion hole and the connecting pin provided in the adjacent divided body, so that the cam ring is integrated after the cam ring is assembled to the cam shaft. Is done. Therefore, the assembly work of the cam ring and the cam shaft to the housing is facilitated.

  In the fuel supply pump of the present invention, the play portion provides a gap between the adjacent divided bodies, and the diameter of the pin insertion hole provided in at least one of the adjacent divided bodies is larger than the diameter of the connecting pin. As a result, the assembly work of the cam ring and the cam shaft to the housing is facilitated, and the contact between the divided body and the plunger or the tappet is reduced.

  Further, in the fuel supply pump of the present invention, since the cam ring is divided corresponding to the plurality of plungers, it becomes easy to prevent the entire cam ring from being inclined due to a load from a certain plunger, and the divided body and the plunger or tappet, etc. And the one-piece contact is reduced.

  Further, in the fuel supply pump of the present invention, the camshaft support portion and the eccentric cam portion satisfy the predetermined relationship, thereby obtaining an integrally formed camshaft in which the camshaft support portion has a larger diameter. Therefore, it is not necessary to prepare a bush or the like that has been conventionally disposed around the camshaft as a measure against high pressure.

  In the fuel supply pump of the present invention, the bearing member disposed between the eccentric cam portion and the cam ring is configured to be separable in a predetermined direction, so that the camshaft is not limited by the size of the bearing member. The diameter of the support portion can be increased. Therefore, the high pressure durability of the fuel supply pump can be improved while avoiding an increase in size of the fuel supply pump.

It is the schematic which shows the structural example of the common rail system provided with the fuel supply pump. It is sectional drawing which shows the structure of the fuel supply pump of 1st Embodiment. It is a perspective view which shows the structure of the camshaft and cam ring with which the fuel supply pump of 1st Embodiment was equipped. It is a figure which shows the assembly method of the cam ring to a cam shaft. It is a figure for demonstrating the contact location of the division body which comprises a cam ring, and a plunger. It is a figure for demonstrating the inclination of a cam ring. It is a figure which shows another structure of a cam ring. It is a figure which shows the structural example of the play part using an elastic member. It is a perspective view which shows the structure of the cam ring with which the fuel supply pump of 2nd Embodiment was equipped. It is a figure which shows the structure of the cam ring which has a play part with which the fuel supply pump of 2nd Embodiment was equipped. It is a figure for demonstrating the structure of the cam ring assembled. It is a figure which shows the assembly method of the cam ring assembled. It is sectional drawing which shows the structure of the conventional fuel supply pump. It is a figure for demonstrating the subject which arises when the conventional cam ring is used.

  Hereinafter, embodiments of the fuel supply pump of the present invention will be described in detail with reference to the drawings. However, this embodiment shows one aspect of the present invention, and does not limit the present invention, and can be arbitrarily changed within the scope of the present invention. In addition, in each figure, what has attached | subjected the same code | symbol has shown the same member, and description is abbreviate | omitted suitably.

[First Embodiment]
1. Accumulated Fuel Supply Device FIG. 1 is a schematic diagram showing an overall configuration of a common rail system 100 including a fuel supply pump 10 according to a first embodiment of the present invention. The common rail system 100 includes a fuel tank 53, a fuel supply pump 10, a common rail 61, and a plurality of injectors (not shown) as main elements.

  In the common rail system 100, the fuel in the fuel tank 53 is pumped up by the feed pump 13 provided in the fuel supply pump 10, and the pressure is increased in the pressurizing chamber 26 of the high pressure pumping unit 20 and is pumped to the common rail 61. . The high-pressure fuel that is accumulated in the common rail 61 and supplied to the injector is injected into the cylinder of the internal combustion engine at a predetermined timing. In the fuel supply pump 10 of this embodiment, the high pressure durability of the fuel supply pump 10 is improved in order to cope with the increase in the pressure in the common rail 61.

2. Fuel Supply Pump (1) Basic Configuration of Fuel Supply Pump The fuel supply pump 10 includes a feed pump 13, a fuel flow control valve 17, and a high-pressure pumping unit 20 as main elements.
Among these, the feed pump 13 has a gear pump structure including, for example, a drive gear attached to the end of the camshaft 31 and a driven gear connected to the drive gear. The feed pump 13 pumps up the fuel in the fuel tank 53 by the negative pressure generated by the rotation of the camshaft 31 and transfers the fuel to the pressurizing chamber 26 of the high-pressure pumping unit 20.

  The fuel flow rate control valve 17 is configured using, for example, an electromagnetic proportional control valve, and is provided in a fuel passage between the feed pump 13 and the high-pressure pumping unit 20. The fuel flow rate control valve 17 adjusts the flow rate of the fuel sent from the feed pump 13 to the high pressure pumping unit 20. For example, the energization amount is adjusted according to the operating state of the internal combustion engine, and the high pressure pumping unit 20. The flow rate of the fuel fed into the pressurizing chamber 26 is adjusted.

Further, the fuel supply pump 10 is provided with an overflow valve 16 branched from the middle of a fuel passage connecting the feed pump 13 and the fuel flow control valve 17 and arranged in parallel with the fuel flow control valve 17. Yes. The overflow valve 16 is opened, for example, when the pressure of the fuel sent to the fuel flow control valve 17 exceeds a specified value, and part of the sent fuel is returned to the fuel tank 53.
In the fuel supply pump 10 of this embodiment, the fuel recirculated through the overflow valve 16 is sent into the cam chamber of the high-pressure pump 20 and used as lubricating oil. During operation, fuel is efficiently utilized as a lubricating oil.

(2) High Pressure Pumping Unit Next, a configuration example of the high pressure pumping unit 20 of the fuel supply pump 10 of the present embodiment will be described with reference to FIGS. 2 (a) to 2 (b) and FIGS. 3 (a) to 3 (b). This will be specifically described. 2A is a cross-sectional view of the fuel supply pump 10 cut along the axial direction of the camshaft 31, and FIG. 2B is a cross-sectional view of the AA cross section of FIG. 3A and 3B are perspective views showing the camshaft 31 and the cam ring 29 provided in the fuel supply pump 10.

  The high-pressure pumping unit 20 includes two pressurizing chambers 26a and 26b that pressurize fuel by two plungers 23a and 23b, respectively, a housing 21, a plunger barrel 19, plungers 23a and 23b, and an inlet valve. 22, an outlet valve 28, a camshaft 31 provided with an eccentric cam portion 31 a, and a cam ring 29 are provided as main elements. The number of plungers and pressurizing chambers can be changed as appropriate.

  The housing 21 serves as a housing of the fuel supply pump 10, and plungers 23 a and 23 b, a cam shaft 31, a cam ring 29, and the like are accommodated in the housing 21. The housing 21 has a shaft hole 21a into which the camshaft 31 is inserted and rotatably supports the camshaft 31, a cam chamber 21b in which the eccentric cam portion 31a and the cam ring 29 are accommodated, and a vertical direction with the cam chamber 21b interposed therebetween. Cylinders 21c and 21d that are open and are respectively mounted with a plunger barrel 19 and holder holes 21e that are mounted with a shaft support holder 27 are provided.

  The camshaft 31 includes an eccentric cam portion 31a and support portions 31b and 31c on both sides of the eccentric cam portion 31a. Among these, the support portion 31 b is rotatably supported in the shaft hole 21 a of the housing 21. The support portion 31 c is rotatably supported in a shaft hole 27 a provided in the shaft support holder 27 that is mounted in the holder hole 21 e of the housing 21.

  A cam ring 29 is disposed around the eccentric cam portion 31 a of the cam shaft 31. Since the center of the circle when the eccentric cam portion 31a is viewed in the direction of the rotation axis Ax of the camshaft 31 is shifted from the rotation axis Ax, when the camshaft 31 rotates, the cam ring 29 rotates the rotation axis of the camshaft 31. Revolves around the eccentric cam portion 31a around Ax.

  The camshaft 31 used in the fuel supply pump 10 of the present embodiment is configured such that the radii of the support portions 31b and 31c are larger than the shortest distance from the rotation axis Ax on the outer peripheral surface of the eccentric cam portion 31a. That is, the camshaft 31 has an integrally formed structure including the eccentric cam portion 31a and the support portions 31b and 31c. Such a structure of the camshaft 31 is realized by the cam ring 29 including a plurality of divided bodies 29a and 29b, as will be described later.

  If the camshaft 31 in which the eccentric cam portion 31a and the support portions 31b and 31c satisfy a predetermined relationship is integrally formed, the diameter of the support portions 31b and 31c of the camshaft 31 is increased as a countermeasure for increasing the common rail pressure. In this case, it is not necessary to prepare a bush or the like as a separate member.

  In the fuel supply pump 10 of the present embodiment, the eccentric cam portion 31a and the camshaft 31 are integrally formed, but the eccentric cam portion 31a and the camshaft 31 are configured separately. May be.

  The plunger barrel 19 is inserted into the cylinders 21c and 21d of the housing 21, and holds the plungers 23a and 23b slidably therein. Inside the plunger barrel 19, pressurizing chambers 26 a and 26 b that are partitioned by plungers 23 a and 23 b and communicate with the inlet valve 22 and the outlet valve 28 are formed.

  Plungers 23 a and 23 b held in the plunger barrel 19 are each provided with a flange portion 24 at the end on the cam chamber 21 b side, and the spring 25 is sandwiched between the flange portion 24 and the plunger barrel 19, thereby 23a and 23b receive the urging force of the spring 25. The end surfaces of the plungers 23a and 23b on the flange portion 24 side are in contact with the cam ring 29. The plungers 23a and 23b are moved by the plunger barrel 19 by the biasing force of the spring 25 and the pressing force by the rotational force of the eccentric cam portion 31a. Move back and forth inside.

  In the high pressure pumping section 20 configured in this way, when the eccentric cam section 31a rotates and the plunger 23a (23b) moves in the direction of the camshaft 31 by the biasing force of the spring 25, the inlet valve 22 opens, and the feed pump The low-pressure fuel sent by the gas flows into the pressurizing chamber 26a (26b) through the inlet valve 22. When the eccentric cam portion 31a further rotates and the pressing force of the cam ring 29 exceeds the urging force of the spring 25, the plunger 23a (23b) rises, and the fuel in the pressurizing chamber 26a (26b) is moved by the plunger 23a (23b). It begins to be pressurized.

  When the inlet valve 22 is closed and the pressure in the pressurizing chamber 26a (26b) exceeds the sum of the spring force of the outlet valve 28 and the pressure in the common rail, the outlet valve 28 is opened, and the high pressure fuel Is pumped to the common rail.

  In the fuel supply pump 10 of the present embodiment, the plungers 23a and 23b are in direct contact with the cam ring 29. In addition to such a configuration, a tappet or tappet roller is provided between the plungers 23a and 23b and the cam ring 29. It can also be set as the structure provided with these.

3. Cam Ring (1) Basic Configuration The cam ring 29 provided in the fuel supply pump 10 of the present embodiment is divided so as to be separable in a direction intersecting the rotation axis Ax of the cam shaft 31 corresponding to the two plungers 23a and 23b. It is comprised by the bodies 29a and 29b. Each divided body 29a (29b) of the cam ring 29 is disposed so as to be interposed between the plunger 23a (23b) and the eccentric cam portion 31a, and the rotational force of the cam shaft 31 is used as the pressing force of the plunger 23a (23b). introduce. The split bodies 29a and 29b of the cam ring 29 are positioned on the contact surfaces S1a and S1b that contact the end surfaces of the plungers 23a and 23b on the flange portion 24 side, and on the eccentric cam portion 31a side. And an arcuate inner peripheral surface S2 corresponding to the shape of the outer peripheral surface.

  The fuel supply pump 10 of the present embodiment is configured to be separable into two divided bodies 29a and 29b corresponding to the two plungers 23a and 23b. However, the number of divided bodies constituting the cam ring 29 is the number of the divided bodies. It can be set in correspondence with the number or independently of the number of plungers. However, the divided portion is configured not to be located at least on the contact surface with the plunger.

  A bearing member 32 is provided on the inner peripheral surface S2 of each divided body 29a, 29b of the cam ring 29, and the inner peripheral surface of the bearing member 32 slides with the outer peripheral surface of the eccentric cam portion 31a. However, when the inner peripheral surface S2 of each divided body 29a, 29 of the cam ring 29 is subjected to surface treatment to improve the strength of the inner peripheral surface S2, the bearing member 32 is omitted and each divided body is omitted. The inner peripheral surface S2 of 29a, 29b and the outer peripheral surface of the eccentric cam portion 31a can also be configured to slide directly.

  In such a cam ring 29, the biasing force of the spring 25 acting on the camshaft 31 side from the plunger 23a (23b) side and the pressure in the pressurizing chamber 26a (26b), and the plunger 23a (23b) from the camshaft 31 side are provided. The pressing force of the eccentric cam portion 31a due to the rotational force of the camshaft 31 acting on the side acts. Therefore, each divided body 29a (29b) of the cam ring 29 is sandwiched between the plunger 23a (23b) and the eccentric cam portion 31a, and the cam ring 29 itself does not rotate, and the eccentric cam portion 31a rotates. Then, the cam shaft 31 revolves around the eccentric cam portion 31a around the rotation axis Ax.

  As described above, in the fuel supply pump 10 of the present embodiment, the cam ring 29 includes the two divided bodies 29a and 29b. Therefore, when the cam ring 29 is assembled to the cam shaft 31, as shown in FIG. Each split body 29a, 29b can be arranged around the eccentric cam portion 31a without inserting the end portion side of the camshaft 31 into the cam ring 29. Therefore, it is not necessary to consider the size of the cam ring 29 when designing the support portions 31b and 31c of the camshaft 31 other than the eccentric cam portion 31a. Therefore, the diameters of the support portions 31b and 31c of the camshaft 31 can be increased regardless of the size of the cam ring 29 and the eccentric cam portion 31a.

  More specifically, as shown in FIGS. 4A to 4B, the cam ring 29 of the present embodiment has a camshaft by disposing the divided bodies 29a and 29b from the periphery of the eccentric cam portion 31a. 31 can be easily assembled to the outer peripheral surface of the eccentric cam portion 31a. Therefore, conventionally, the support portion 31b of the camshaft 31 that has a radius r ′ having the same size as the shortest distance n from the rotation axis Ax of the camshaft 31 on the outer peripheral surface of the eccentric cam portion 31a at the maximum (in the drawing). The diameter is increased without changing the size of the cam ring 29 or the eccentric cam portion 31a. As a result, the surface pressure acting between the support portion 31b of the camshaft 31 and the shaft hole 21a of the housing 21 is dispersed by the load from the plungers 23a and 23b, thereby improving wear resistance and durability.

  Further, in the case of the cam ring 29 composed of the separable divided bodies 29a and 29b as described above, even if the diameter of the support portion 31b is changed, the eccentric cam portion is not changed as long as the diameter of the eccentric cam portion 31a does not change. The same cam ring 29 composed of the divided bodies 29a and 29b having the inner peripheral surface S2 adapted to 31a can be used. Therefore, the common cam ring 29 is used for the different fuel supply pumps 10 to reduce the cost.

  Further, if the cam ring 29 is composed of separable divided bodies 29a and 29b, the inner peripheral surface S2 of each of the divided bodies 29a and 29b can be directed in a desired direction. For example, a plasma CVD apparatus or the like is used. When performing the surface treatment of the inner peripheral surface S2 of each divided body 29a, 29b, the surface treatment can be efficiently performed.

  Furthermore, in the case of the cam ring 29 composed of separable divided bodies 29a and 29b, the lubricating oil supplied into the cam chamber 21b is allowed to flow between the outer peripheral surface of the eccentric cam portion 31a and each of the divided bodies 29a and 29b or the bearing member 32. It becomes easy to be guided to the sliding portion between the inner peripheral surface. Therefore, during driving of the fuel supply pump 10, seizure or wear of the sliding portion between the outer peripheral surface of the eccentric cam portion 31 a and each of the divided bodies 29 a and 29 b or the inner peripheral surface of the bearing member 32 is less likely to occur.

(2) Playing portion In the cam ring 29 shown in FIGS. 2B and 3B, each divided body 29a (29b) is moved in the rotational direction of the camshaft 31 by the other divided body 29b (29a). A play portion 30 is provided to prevent the movement of the play.
The idler 30 receives the pressure in the pressurizing chamber 26a through the plunger 23a when the fuel supply pump 10 is driven and the one split body 29a presses the plunger 23a by the rotational force of the camshaft 31. This is an element for preventing the other divided body 29b from being tilted by tilting and tilting the divided body 29b.

  More specifically, as described above, since the cam ring 29 revolves around the rotation axis Ax of the camshaft 31, the contact portions of the divided bodies 29a and 29b with the plungers 23a and 23b are as shown in FIG. As shown in (d) to (d), the camshaft 31 moves while being shifted depending on the rotation angle of the eccentric cam portion 31a. Therefore, in a state where the contact points of the plungers 23a and 23b are deviated from the centers of the respective divided bodies 29a and 29b, the respective divided bodies 29a and 29b are caused by the pressure acting between the plungers 23a and 23b and the divided bodies 29a and 29b. 29b will be in the state which is easy to move to the circumferential direction of the eccentric cam part 31a.

  A larger force is applied when the eccentric cam portion 31a pushes up the plungers 23a and 23b (when fuel is pressurized) than when the plunger 23a and 23b pushes down the eccentric cam portion 31a (when fuel is sucked). Therefore, in the state shown in FIGS. 5A and 5B while the camshaft 31 makes one rotation, the contact surface S1a of the divided body 29a on the pressurizing chamber 26a side where the fuel is pressurized is the end surface of the plunger 23a. 5 (c) to 5 (d), the contact surface S1b of the split body 29b on the pressurizing chamber 26b side where the fuel is pressurized is easily tilted with respect to the end surface of the plunger 23b. Become.

At this time, if the cam ring 29 is not provided with a play portion, as shown in FIG. 6A, the contact surface S1a ′ of the split member 29a ′ on the plunger 23a ′ side to which the fuel is pressurized is moved to the plunger 23a ′. As a result, the contact surface S1b ′ of the other divided body 29b ′ is also tilted with respect to the end surface of the plunger 23b ′.
On the other hand, if the play part 30 is provided in the cam ring 29, as shown in FIG.6 (b), the division body 29a by the side of the pressurization chamber 26a to which a fuel will be pressurized will be pushed by the plunger 23a. Even if it is tilted, the other split body 29b is not affected, and its contact surface S1b does not tilt with respect to the end surface of the plunger 23b.

  In the cam ring 29 shown in FIG. 2B and FIG. 3B, a play portion 30 is formed by providing a gap between the divided bodies 29a and 29b. Therefore, the other divided body 29b (29a) is not pushed by the movement of the one divided body 29a (29b). Therefore, the contact surface S1b (S1a) of the other divided body 29b (29a) and the plunger 23b (23a) due to the inclination of the one divided body 29a (29b) by the pressure from the plunger 23a (23b) in the fuel pressurization state. ) Is prevented. As a result, damage to the divided body 23b (23a) is reduced, and the high-pressure durability of the fuel supply pump 10 is improved.

In constructing the play portion 30 constituted by such a gap, the position, shape, and width of the gap are not limited, and are appropriately designed in consideration of the strength and moving range of each divided body 29a, 29b. be able to.
For example, as shown in FIG. 7, each of the divided bodies 29 a and 29 b is provided with unevenness at the end facing the other divided bodies, and the unevenness of each of the divided bodies 29 a and 29 b is fitted to each other, If each divided body 29a, 29b is in contact only in the direction of the rotational axis Ax of the camshaft 31, a play portion 30A consisting of a gap is formed, and the divided bodies 29a, 29b are directed in the direction of the rotational axis Ax. Is prevented from being displaced.

Moreover, the play part 30 provided in the cam ring 29 is not limited to what is comprised by providing a clearance gap.
For example, FIG. 8 shows a cam ring 29A in which a play portion 40 is formed by sandwiching an elastic member 40A such as elastic rubber between the divided bodies 29a and 29b. In this way, even in the play portion 40 configured using the elastic member 40A, the force of pressing the other divided body 29b (29a) is reduced by the movement of one divided body 29a (29b), and the other Even the contact surface S1b (S1a) of the divided body 29b (29a) is prevented from being inclined with respect to the end surface of the plunger 29b (29a).

  The elastic member 40A sandwiched between the divided bodies 29a and 29b is fixed to one of the divided bodies 29a and 29b in consideration of work efficiency during assembly. Furthermore, when each divided body 29a, 29b is arranged around the eccentric cam portion 31a of the camshaft 31, an adhesive sheet is arranged so as to be fixed to both divided bodies 29a, 29b. The assembly work to the fuel supply pump 10 after the cam ring 29 is arranged on the camshaft 31 is facilitated.

[Second Embodiment]
The fuel supply pump according to the second embodiment of the present invention basically has the same configuration as the fuel supply pump of the first embodiment except for the configuration of the cam ring. Hereinafter, the fuel supply pump of this embodiment will be described focusing on the configuration of the cam ring.

1. Basic Configuration of Cam Ring FIGS. 9 (a) to 9 (b) show that the divided bodies 49a and 49b are biased by inserting the connecting pins 34 into the pin insertion holes 33a and 33b provided in the divided bodies 49a and 49b. The structure of the cam ring 49 which connected each division body 49a, 49b after arrange | positioning around the core cam part 31a is shown.
Specifically, the concavo-convex portions symmetrical to each other are provided at the end of each divided body 49a, 49b of the cam ring 49 facing the other divided body. The concave and convex portions of each of the divided bodies 49a and 49b are provided with pin insertion holes 33a and 33b that communicate in the direction of the rotation axis Ax of the camshaft 31 after assembly. And each division body 49a, 49b is arrange | positioned around the eccentric cam part 31a, and an unevenness | corrugation is fitted, and the connection pin 34 is inserted with respect to pin insertion hole 33a, 33b, thereby each division body 49a, 49b is connected. In the example shown in FIGS. 9A to 9B, the connecting pin 34 is designed to be lightly press-fitted into the pin insertion holes 33a and 33b so that the connecting pin 34 does not fall off.

  Even in the cam ring 49 having the configuration shown in FIGS. 9A to 9B, the cam ring 49 is composed of two divided bodies 49 a and 49 b, so that when the cam ring 49 is assembled to the cam shaft 31, Without inserting the end portion side of the camshaft 31, the divided bodies 49a and 49b can be arranged around the eccentric cam portion 31a. Therefore, it is not necessary to consider the size of the cam ring 49 when designing the support portions 31b and 31c of the camshaft 31 other than the eccentric cam portion 31a. Therefore, the diameters of the support portions 31b and 31c of the camshaft 31 can be increased regardless of the sizes of the cam ring 49 and the eccentric cam portion 31a.

  Further, the divided bodies 49a and 49b of the cam ring 49 are provided with projections and recesses that fit with each other, and the divided bodies 49a and 49b are also in contact with each other in the direction of the rotation axis Ax of the camshaft 31. The positional deviation between the 49a and 49b in the direction of the rotation axis Ax is prevented.

2. Play part Also in the cam ring 49 provided in the fuel supply pump of the present embodiment, each split body 49a (49b) is a play part for preventing movement of the camshaft 31 in the rotational direction by the other split body 49b (49a). Can be provided.

  10 (a) to 10 (b), a gap is provided between the divided bodies 49a and 49b, and the pin insertion holes 33a and 33b among the pin insertion holes 33a and 33b have a diameter of the connecting pin 34. The play parts 50a and 50b comprised by making it larger than the diameter of are shown. In the case of the cam ring 49 provided with such play portions 50a and 50b, one divided body 49a (49b) is connected to the other within the range of the difference between the diameter of the pin insertion holes 33a and 33b and the diameter of the connecting pin 34. It becomes possible to move without pressing the divided body 49b (49a). Therefore, when the fuel supply pump is driven, when one of the divided bodies 49a is inclined by receiving the pressure in the pressurizing chamber 26a via the plunger 23a, the other divided body 49b is affected and the divided body 49b is reached. It is prevented that the heel tilts.

  In particular, as shown in FIGS. 10A to 10B, a part of the pins that are not enlarged by making the diameter of only one of the pin insertion holes 33 a and 33 b larger than the diameter of the connecting pin 34. Since the connecting pin 34 is fixed in the insertion holes 33a and 33b, the play portions 50a and 50b are formed in the cam ring 49, and the connecting pin is prevented from falling off after the cam ring 49 is assembled.

3. Cam ring assembly When a connecting pin is inserted into a pin insertion hole provided in each divided body to configure each divided body as a cam ring, one of the pin insertion holes is formed as a long hole. It can also be configured as a cam ring assembly in which each divided body can be separated by the moving range of the connecting pin.

11A and 11B show a configuration example in which the cam ring is assembled. FIG. 11A shows a side view of the cam ring assembly 80, and FIG. 11B shows the configuration in FIG. The front view which looked at the cam ring assembly 80 in the direction of arrow B of FIG.
Of the cam ring assembly 80, the divided body 81a is provided with a pin press-fitting hole 83a having a diameter into which the connecting pin 85 can be press-fitted. A possible long hole 83b is provided. The length of the long hole 83b of the divided body 81b is such that the eccentric cam portion and the support portion of the camshaft are at least in the space 87 formed by the inner peripheral surface S2 of the divided body 81a and the inner peripheral surface S2 of the divided body 81b. The length that can be inserted is set.

  Since the connecting pin 85 is press-fitted into the pin press-fitting hole 83a of the divided body 81a, it does not fall off, and the divided body 81a and the divided body 81b are stored together when the cam ring assembly 80 is stored. Further, when the cam ring assembly 80 is assembled to the cam shaft 31, as shown in FIGS. 12A and 12B, the divided bodies 81 a and 81 b are separated so that the cam shaft 31 is placed in the space 87 of the cam ring assembly 80. By inserting from the support portion 31b side, the cam ring assembly 80 can be disposed around the eccentric cam portion 31a.

With the cam ring assembly 80 configured as described above, the assembly work to the cam shaft 31 and the parts management are facilitated.
Note that the hole on the divided body 81a side in the cam ring assembly 80 of FIGS. 11A to 11B may be a long hole, and the hole on the divided body 81b side may be a pin press-fit hole.

10: Fuel supply pump, 13: Feed pump, 16: Overflow valve, 17: Fuel flow control valve, 19: Plunger barrel, 20: High pressure pumping part, 21: Housing, 21a: Shaft hole, 21b: Cam chamber, 21c 21d: cylinder, 21e: holder hole, 22: inlet valve, 23 / 23a / 23b: plunger, 24: collar, 25: spring, 26 / 26a / 26b: pressurizing chamber, 27: shaft support holder, 27a: shaft Hole, 28: Outlet valve, 29/49: Cam ring, 29a / 29b / 49a / 49b: Divided body, 30 / 30A / 40 / 50a / 50b: Play part, 31: Cam shaft, 31a: Eccentric cam part, 31b 31c: support portion, 32: bearing member, 33: pin insertion hole, 34: connecting pin, 40A, elastic member, 3: Fuel tank, 61: Common rail, 80: Cam ring assembly, 81a and 81b: Divided body, 83a: Pin press-fitting hole, 83b: Long hole, 85: Connecting pin, 87: Space, 100: Common rail system, S1a and S1b: Contact surface, S2: inner peripheral surface

Claims (5)

A camshaft having an eccentric cam portion;
A plurality of plungers arranged on the outer peripheral side of the eccentric cam portion, and reciprocatingly moving with the rotation of the eccentric cam portion to pressurize and feed fuel in a pressurized chamber;
A cam ring that is disposed between the eccentric cam portion and the plunger and revolves around the eccentric cam portion around a rotation axis of the cam shaft as the eccentric cam portion rotates.
A fuel supply pump comprising: a cam chamber that houses the eccentric cam portion and the cam ring; and a housing having a shaft hole that rotatably supports the camshaft.
Said cam ring, said Ri Do a plurality of divided bodies separable in a direction intersecting with the rotational axis of the camshaft, because each of the divided body is not restricted from moving in the rotational direction of the cam shaft by other divided member Have a play part,
The play portion is configured by sandwiching an elastic body between the adjacent divided bodies .   A camshaft having an eccentric cam portion;
  A plurality of plungers arranged on the outer peripheral side of the eccentric cam portion, and reciprocatingly moving with the rotation of the eccentric cam portion to pressurize and feed fuel in a pressurized chamber;
  A cam ring that is disposed between the eccentric cam portion and the plunger and revolves around the eccentric cam portion around a rotation axis of the cam shaft as the eccentric cam portion rotates.
  A fuel supply pump comprising: a cam chamber that houses the eccentric cam portion and the cam ring; and a housing having a shaft hole that rotatably supports the camshaft.
  The cam ring includes a plurality of divided bodies separable in a direction intersecting with the rotation axis of the cam shaft, and each of the divided bodies is not restricted by the other divided bodies from moving in the rotational direction of the cam shaft. Have a play part,
  Adjacent divided bodies of the plurality of divided bodies are each provided with a pin insertion hole extending in the rotation axis direction of the camshaft and assembled by inserting a connecting pin into the pin insertion hole. A gap is provided between the adjacent divided bodies, and the diameter or width of the pin insertion hole provided in at least one of the adjacent divided bodies is made larger than the diameter of the connecting pin. A fuel supply pump. Said cam ring, a fuel supply pump according to claim 1 or 2, characterized in that it is divided corresponding to a plurality of said plungers. Radius of the cam shaft portion to be supported by the shaft hole of the housing, one of the claims 1-3, characterized in that longer than the shortest distance from the rotational axis of the outer peripheral surface of the eccentric cam portion A fuel supply pump according to claim 1. When the bearing member is disposed between the eccentric cam portion and the cam ring, the bearing member is configured to be separable in a direction intersecting with a rotation axis of the cam shaft. The fuel supply pump according to any one of 1 to 4 .

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