JP4941272B2 - pump - Google Patents

Description

  The present invention relates to a pump that pumps fluid by reciprocating a tappet and a plunger as a cam ring revolves, and is particularly suitable for a fuel injection pump used in a pressure accumulation fuel injection device for a diesel engine.

  In the conventional fuel injection pump disclosed in Patent Document 1, the cam ring revolves without rotating around the cam shaft, the tappet reciprocates while sliding with the cam ring, and the plunger reciprocates with the tappet. Is supposed to be pumped. More specifically, a tappet shoe is press-fitted into the tappet so that the cam ring and the tappet shoe slide. Then, fuel is introduced into the chamber in which the cam ring is accommodated, and the sliding portion between the cam ring and the tappet shoe is lubricated by the fuel.

In another conventional fuel injection pump, a hard coating layer is formed on the surface of the cam ring to improve the wear resistance and seizure resistance of the sliding portion between the tappet and the cam ring.
JP 2000-145572 A

  However, in fuel injection pumps, the surface pressure load on the sliding part of the tappet and cam ring increases due to the high injection pressure, and the sliding speed of the sliding part of the tappet and cam ring increases due to the increase in pump operating speed. In addition, the use environment is becoming harsh, such as the use of poor fuels and biofuels, resulting in a decrease in lubrication performance, and it is required to further improve wear resistance and seizure resistance.

  In view of the above points, an object of the present invention is to improve wear resistance and seizure resistance of a sliding portion in a pump in which a tappet reciprocates as the cam ring revolves.

  In order to achieve the above object, according to the first aspect of the present invention, the rotating cam shaft (14) and the cam that is arranged eccentrically with respect to the cam shaft (14) and rotates together with the cam shaft (14). (17) and a cam ring (18) which is arranged on the outer peripheral side of the cam (17) and revolves around the cam shaft (14) without rotating, and reciprocates as the cam ring (18) revolves. In a pump comprising a tappet (202) and a plunger (201) that reciprocates with the tappet (202) to pump fluid, a flat cam ring sliding surface (181a) formed on the cam ring (18) and a tappet ( 202) and a flat tappet sliding surface (202a) formed on the cam ring sliding surface (181a) and the tappet sliding surface (202a). (18) and the tappet (202) movable in relative movement direction (X) of the plate-like slider (31 to 33) is characterized in that it is interposed.

  According to this, since it can slide in multiple places, such as between a cam ring (18) and sliders (31-33), and between a tappet (202) and sliders (31-33), the amount of slip is distributed. Since the amount of sliding is dispersed, the amount of sliding for each sliding portion is reduced and the sliding speed at each sliding portion is reduced, so that the wear resistance and seizure resistance of the sliding portion are reduced. Can be improved.

  In addition, since the sliding amount of the sliding portion having a low friction coefficient among the plurality of sliding portions is larger than the sliding amount of the sliding portion having a high friction coefficient, in other words, the sliding portion suitable for sliding is slippery. As the amount increases, the sliding amount of the sliding portion that is not suitable for sliding decreases, so that the wear resistance and seizure resistance of the sliding portion can be further improved.

  According to a second aspect of the present invention, in the pump according to the first aspect, the sliders (31 to 33) are a plurality of sheets and are stacked.

  According to this, since it can slide also between adjacent sliders (31 to 33), the amount of slip is further dispersed. Therefore, the wear resistance and seizure resistance of the sliding portion can be further improved.

  As in the invention described in claim 3, in the pump according to claim 1 or 2, the cam ring (18) includes a cam ring recess (181b) in which the slider (31-33) is accommodated, and the cam ring recess Of the wall surfaces surrounding (181b), the relative movement direction wall surface (181c) located in the relative movement direction (X) of the slider (31-33) in the relative movement direction (X) within the cam ring recess (181b). It can be set as the structure by which a movement range is controlled.

  As in the invention according to claim 4, in the pump according to claim 1 or 2, the tappet (202) includes a tappet recess (202b) in which the sliders (31 to 33) are accommodated, and the tappet recess Of the slider (31-33) in the relative movement direction (X) in the tappet recess (202b) by the relative movement direction wall surface (202c) located in the relative movement direction (X) of the wall surfaces surrounding (202b). It can be set as the structure by which a movement range is controlled.

  According to a fifth aspect of the present invention, in the pump according to the third or fourth aspect, the movement restricting member (40) made of an elastic body is arranged on the relative movement direction wall surface (181c, 202c). .

  According to this, it avoids that the relative movement direction wall surface (181c, 202c) and the slider (31-33) collide directly, and suppresses wear of the relative movement direction wall surface (181c) and the slider (31-33). be able to.

  According to a sixth aspect of the present invention, in the pump according to any one of the first to fifth aspects, the cam ring (18), the tappet (202), and the slider (31 to 33) are made of metal, and the slider (31 To 33), a coating layer having a hardness higher than that of the base metal is formed.

  According to this, since the friction coefficient can be lowered by the coating layer, the wear resistance and seizure resistance of the sliding portion can be further improved.

  In addition, the code | symbol in the bracket | parenthesis of each means described in a claim and this column shows the correspondence with the specific means as described in embodiment mentioned later.

(First embodiment)
A first embodiment of the present invention will be described. FIG. 1 is a sectional view of a pump according to the first embodiment of the present invention, and FIG. 2 is a sectional view taken along the line AA of FIG.

  The pump of this embodiment is used in an accumulator fuel injection device for an internal combustion engine (more specifically, a diesel engine), and pressurizes and supplies fuel to a common rail that accumulates high-pressure fuel.

  As shown in FIGS. 1 and 2, the housing of the pump includes a housing body 11 made of aluminum alloy and a pair of cylinder heads 12 made of iron-based metal. A cam chamber 13 to which fuel is supplied from a feed pump described later is formed in the housing main body 11, and both ends of the cam chamber 13 are closed by the cylinder head 12. The cam chamber 13 is connected to a fuel tank (not shown).

  The cam shaft 14 is made of ferrous metal and is driven to rotate by a diesel engine (not shown). The cam shaft 14 is rotatably supported by the housing body 11 via two bushes 15. The bush 15 has a cylindrical shape and is press-fitted and fixed to the housing body 11. The cam shaft 14 and the housing body 11 are sealed with an oil seal 16. A cam 17 having a circular cross section is formed eccentrically with respect to the cam shaft 14 at an intermediate portion in the axial direction of the cam shaft 14.

  A cam ring 18 that revolves around the cam shaft 14 is fitted to the outer periphery of the cam 17. The cam ring 18 includes a cam ring main body 181 and a bush 182 integrated with the cam ring main body 181. More specifically, the cam ring body 181 is made of an iron-based metal (for example, chromium steel), has an outer shape of a quadrangular prism shape, and has a circular through hole. The bush 182 is formed in a cylindrical shape and is press-fitted into a through hole of the cam ring main body 181 so as to be slidable with the cam 17. The cam 17 and the cam ring 18 are accommodated in the cam chamber 13.

  On both sides of the cam ring 18, a pressure feeding member 20 made of an iron-based metal (for example, alloy tool steel) that reciprocates following the revolution of the cam ring 18 is disposed. The pressure feeding member 20 includes a columnar plunger 201 that is inserted into the cylinder head 12 so as to be reciprocally movable, and a bowl-shaped tappet 202 that is disposed in the cam chamber 13 and is opposed to the cam ring 18.

  Between the cam ring 18 and the tappet 202, sliders 31 to 33 described later are interposed. Further, the pressure feeding member 20 is urged toward the cam ring 18 by a spring 21 disposed in the cam chamber 13.

  In the cylinder head 12, a fuel pressurizing chamber 22 to which fuel is supplied from the feed pump 25 is formed on one end side (counter tappet 202 side) of the plunger 201 of the pressure feeding member 20. Further, in the cylinder head 12, only the fuel flow from the feed pump 25 to the fuel pressurizing chamber 22 and the inlet side check valve 23 that allows only the fuel flow from the feed pump 25 to the common rail. A permissible outlet check valve 24 is provided.

  An inner gear type feed pump 25 is coupled to one end side of the cam shaft 14. The feed pump 25 is housed in the pump cover 26 so as to be rotatable. The feed pump 25 is rotationally driven by the camshaft 14 to pressurize and discharge the fuel sucked from the fuel tank.

  The fuel discharged from the feed pump 25 is supplied to the fuel pressurizing chamber 22 through a fuel passage (not shown) and an inlet side check valve 23. A metering valve (not shown) for metering the amount of fuel supplied to the fuel pressurizing chamber 22 according to the operating state of the internal combustion engine is provided in the middle of the fuel passage.

  In order to supply a part of the fuel discharged from the feed pump 25 to the cam chamber 13, the fuel injection pump has the following configuration. First, the pump cover 26 is formed with a communication passage 26 a for guiding the fuel discharged from the feed pump 25 to the end surface on one end side of the cam shaft 14. The cam shaft 14 is formed with a hole-shaped axial lubricating oil passage 14 a extending in the axial direction of the cam shaft 14. The axial lubricating oil path 14a is opened at one end face of the camshaft 14 and communicates with the communication path 26a. The camshaft 14 is formed with a hole-shaped radial lubricating oil path 14b that extends in the radial direction of the camshaft 14 and communicates the axial lubricating oil path 14a with the outer peripheral surface of the cam 17.

  3 is an enlarged view of a portion B in FIG. 2, and FIG. 4 is a view taken in the direction of arrow C in a state in which the pumping member 20 is removed in FIG.

  As shown in FIGS. 3 and 4, the cam ring 18 moves relative to the pressure feeding member 20 in the direction of the arrow X along with the revolution. The relative movement direction X is a direction perpendicular to the axis of the pressure feeding member 20 (that is, the reciprocating direction of the pressure feeding member 20) and the axis of the cam shaft 14.

  A flat cam ring sliding surface 181a formed on the cam ring main body 181 and a flat tappet sliding surface 202a formed on the tappet 202 are opposed to each other. The cam ring main body 181 has the cam ring sliding surface 181a as a bottom portion. A rectangular parallelepiped cam ring recess 181b is formed, and three sliders 31 to 33 are accommodated in the cam ring recess 181b.

  The sliders 31 to 33 are rectangular parallelepiped thin plates made of iron-based metal (for example, alloy tool steel), and are stacked between the tappet sliding surface 202a and the cam ring sliding surface 181a, and are sandwiched between the cam ring main body 181 and the tappet 202. Has been. The slider 31 in contact with the tappet sliding surface 202a is the first slider, the slider 33 in contact with the cam ring sliding surface 181a is the third slider, and the slider 32 between the first slider 31 and the third slider 33 is the second slider. To do.

  Each of the first to third sliders 31 to 33 is independently movable in the relative movement direction X within the cam ring recess 181b. The movement range of the first to third sliders 31 to 33 in the relative movement direction X in the cam ring recess 181b is determined by the relative movement direction wall surface 181c located in the relative movement direction X of the wall surfaces surrounding the cam ring recess 181b. Are now regulated. The length Ls of the first to third sliders 31 to 33 in the relative movement direction X is set to be larger than the outer diameter Dt of the tappet 202.

  Between the relative movement direction wall surface 181c and the first to third sliders 31 to 33, a movement restricting member 40 made of an elastic body (for example, rubber) is disposed. More specifically, the movement restricting member 40 is fixed to the relative movement direction wall surface 181c by bonding or the like.

  Next, the operation of the pump will be described. When the camshaft 14 is driven and rotated by the diesel engine, the feed pump 25 is driven by the rotating operation of the camshaft 14, and the feed pump 25 sucks fuel from the fuel tank, pressurizes it, and discharges it.

  Further, the cam 17 rotates with the rotation of the cam shaft 14, the cam ring 18 revolves without rotating with the rotation of the cam 17, and the pressure feeding member 20 reciprocates with the rotation of the cam ring 18.

  When the pumping member 20 at the top dead center moves toward the bottom dead center with the revolution of the cam ring 18, the fuel discharged from the feed pump 25 flows into the fuel pressurizing chamber 22 through the inlet side check valve 23. .

  When the pressure-feeding member 20 that has reached the bottom dead center moves again toward the top dead center, the inlet-side check valve 23 closes, and the fuel pressure in the fuel pressurizing chamber 22 rises. When the fuel pressure in the fuel pressurizing chamber 22 rises, the outlet side check valve 24 opens and high pressure fuel is supplied to the common rail.

  On the other hand, a part of the fuel discharged from the feed pump 25 is guided to one end face of the camshaft 14 by the communication passage 26a, and the cam 17 and the cam ring via the axial lubricating oil passage 14a and the radial lubricating oil passage 14b. 18 is guided between the 18 bushes 182 and further flows between the cam 17 and the bush 182 and flows into the cam chamber 13. Accordingly, the sliding portion between the cam 17 and the bush 182 is lubricated, and the sliding portion between the tappet 202, the first to third sliders 31 to 33, and the cam ring body 181 is lubricated.

  During operation of the pump, between the tappet 202 and the first slider 31, between the first slider 31 and the second slider 32, between the second slider 32 and the third slider 33, and between the third slider 33 and the cam ring body 181. And can move relative to each other. As described above, the sliding amount (relative movement amount) is dispersed since the sliding is possible at the four sliding portions. Since the amount of sliding is dispersed, the amount of sliding for each sliding portion is reduced and the sliding speed at each sliding portion is reduced, so that the wear resistance and seizure resistance of the sliding portion are reduced. Can be improved.

  In addition, the sliding amount of the sliding portion having a low friction coefficient among the four sliding portions is larger than the sliding amount of the sliding portion having a high friction coefficient. Therefore, for example, the sliding amount of the sliding portion having a high friction coefficient due to oil film breakage is reduced, so that the wear resistance and seizure resistance of the sliding portion can be further improved.

  Further, since the movement restricting member 40 avoids a direct collision between the relative movement direction wall surface 181c and the first to third sliders 31 to 33, the wear of the relative movement direction wall surface 181c and the first to third sliders 31 to 33 is avoided. Can be suppressed.

(Second Embodiment)
A second embodiment of the present invention will be described. FIG. 5 is a view showing a main part of a pump according to the second embodiment of the present invention. In the present embodiment, the sliders 31 to 33 are accommodated in the tappet 202. In addition, the same code | symbol is attached | subjected to the same or equivalent part as 1st Embodiment, and the description is abbreviate | omitted.

  As shown in FIG. 5, the tappet 202 has a rectangular parallelepiped-shaped tappet recess 202b with the tappet sliding surface 202a as a bottom, and the first to third sliders 31 to 33 are accommodated in the tappet recess 202b. ing.

  The first to third sliders 31 to 33 are independently movable in the relative movement direction X within the tappet recess 202b. The movement range of the first to third sliders 31 to 33 in the relative movement direction X within the tappet recess 202b is determined by the relative movement direction wall 202c located in the relative movement direction X among the wall surfaces surrounding the tappet recess 202b. Are now regulated.

  Between the relative movement direction wall surface 202c and the first to third sliders 31 to 33, a movement restricting member 40 made of an elastic body (for example, rubber) is disposed. More specifically, the movement restricting member 40 is fixed to the relative movement direction wall surface 202c by bonding or the like.

  During operation of the pump, as in the first embodiment, between the tappet 202 and the first slider 31, between the first slider 31 and the second slider 32, between the second slider 32 and the third slider 33, Between the third slider 33 and the cam ring main body 181, it can slide and relatively move. Therefore, similarly to the first embodiment, the wear resistance and seizure resistance of the sliding portion can be improved.

  Further, since the movement restricting member 40 avoids a direct collision between the relative movement direction wall surface 202c and the first to third sliders 31 to 33, the wear of the relative movement direction wall surface 202c and the first to third sliders 31 to 33 is avoided. Can be suppressed.

(Other embodiments)
In each of the above embodiments, a plurality of sliders 31 to 33 are used, but one slider may be used.

  The movement restricting member 40 may be made of a material other than the elastic body as long as it can suppress wear of the relative movement direction wall surfaces 182c and 202c and the first to third sliders 31 to 33. Further, the movement restricting member 40 may be eliminated.

  Further, the cam ring main body 181, the pressure feeding member 20, and the first to third sliders 31 to 33 are made of an iron-based metal, and the surface of the first to third sliders 31 to 33 is higher in hardness than the base metal. A coating layer may be formed. According to this, since the friction coefficient can be lowered by the coating layer, the wear resistance and seizure resistance of the sliding portion can be further improved.

It is sectional drawing of the pump which concerns on 1st Embodiment of this invention. It is sectional drawing which follows the AA line of FIG. It is a figure which expands and shows the B section of FIG. It is C arrow line view of the state which removed the pumping member 20 in FIG. It is a figure which shows the principal part of the pump which concerns on 2nd Embodiment of this invention.

Explanation of symbols

14 Cam Shaft 17 Cam 18 Cam Ring 31 Slider 32 Slider 33 Slider 181a Cam Ring Sliding Surface 201 Plunger 202 Tappet 202a Tappet Sliding Surface

Claims (6)

A rotating cam shaft (14), a cam (17) arranged eccentrically with respect to the cam shaft (14) and rotating integrally with the cam shaft (14), and an outer peripheral side of the cam (17) The cam ring (18) that revolves around the cam shaft (14) without revolving, the tappet (202) that reciprocates as the cam ring (18) revolves, and the reciprocating movement with the tappet (202). And a plunger (201) for pumping fluid,
The flat cam ring sliding surface (181a) formed on the cam ring (18) and the flat tappet sliding surface (202a) formed on the tappet (202) are opposed to each other.
A plate-like slider (movable in the relative movement direction (X) between the cam ring (18) and the tappet (202) between the cam ring sliding surface (181a) and the tappet sliding surface (202a). 31 to 33) are interposed.   The pump according to claim 1, wherein the sliders (31 to 33) are plural and stacked. The cam ring (18) includes a cam ring recess (181b) in which the slider (31-33) is accommodated,
Of the wall surfaces surrounding the cam ring recess (181b), the relative movement direction wall surface (181c) located in the relative movement direction (X) moves toward the relative movement direction (X) in the cam ring recess (181b). The pump according to claim 1 or 2, wherein a movement range of the slider (31 to 33) is restricted. The tappet (202) includes a tappet recess (202b) in which the slider (31-33) is accommodated.
The relative movement direction wall surface (202c) located in the relative movement direction (X) among the wall surfaces surrounding the tappet depression portion (202b) moves toward the relative movement direction (X) in the tappet depression portion (202b). The pump according to claim 1 or 2, wherein a movement range of the slider (31 to 33) is restricted.   The pump according to claim 3 or 4, wherein a movement restricting member (40) made of an elastic body is arranged on the wall surface (181c, 202c) in the relative movement direction. The cam ring (18), the tappet (202), and the slider (31-33) are made of metal,
The pump according to any one of claims 1 to 5, wherein a coating layer having a hardness higher than that of a base metal is formed on a surface of the slider (31 to 33).

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