JP2012026358A - Cooling structure for fuel pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling structure for a fuel pump that improves starting capability of an internal combustion engine by preventing a vapor from occurring in a fuel after the internal combustion engine is stopped.SOLUTION: The cooling structure for the fuel pump includes: a slope 93 where a cylinder head cover 91 is sloped and provided from an end part to the other end to a horizontal surface and a high-pressure fuel pump 4 is provided in a lower part in a slope direction of the cylinder head cover 91 and that extends to the high-pressure pump from a higher part of the slope direction of the cylinder head cover on an inner circumference of the cylinder head cover 91; and a plurality ribs 94 that are formed in the inner circumference of the cylinder head cover 91 comprising the slope 93, that protrudes downward from the inner circumference of the cylinder head cover 91 and extends from the inner circumference side 91c of the cylinder head cover 91 toward the high-pressure fuel pump 4.

Description

  The present invention relates to a fuel pump cooling structure, and more particularly to a fuel pump cooling structure that is installed in a cylinder head cover of an internal combustion engine and supplies fuel to a fuel injection valve.

  Conventionally, for example, in an internal combustion engine in which high pressure is required for fuel supplied to a fuel injection valve, such as a direct injection type internal combustion engine, the fuel sent from the fuel tank is added by a high-pressure fuel pump. The pressure is supplied to the fuel injection valve.

  A conventional high-pressure fuel pump of this type is attached to a cylinder head cover of an internal combustion engine through a pump housing, and is inserted into the fuel pump main body and the fuel pump main body so as to be able to reciprocate so that fuel is supplied together with the fuel pump main body. A plunger that forms a pressurizing chamber for pressurization, and a lifter that moves the plunger in a direction in which the pressurizing chamber contracts by applying a pressing force from a driving cam attached to a camshaft attached to the cylinder head to the plunger. (For example, refer to Patent Document 1).

JP 2001-295730 A JP-A-60-95184

  In such a conventional high-pressure fuel pump, the internal combustion engine body (cylinder head) accompanying the stoppage of the cooling system of the internal combustion engine or the like when the internal combustion engine is immediately stopped from the high load operation state, that is, at the time of so-called dead soak. The temperature of the high-pressure fuel pump rises due to radiant heat caused by the temperature rise of the parts and cylinder blocks).

  For this reason, the temperature of the fuel passing through the high-pressure fuel pump also rises and exceeds the vaporization temperature of the fuel, and vapor (bubbles) may be generated in the fuel. As a result, the startability of the internal combustion engine may be deteriorated due to the fuel containing the vapor being injected together with the fuel from the fuel injection valve.

  Here, during operation of the internal combustion engine, there is one that prevents heating during driving of the high-pressure fuel pump by injecting oil pumped by the oil pump to the high-pressure fuel pump (see, for example, Patent Document 2). However, this prior art can suppress the generation of vapor during the operation of the internal combustion engine, but it cannot supply oil to the high-pressure fuel pump after the internal combustion engine is stopped at the time of dead soak. The generation of vapor cannot be suppressed.

  The present invention has been made to solve the conventional problems as described above, and can prevent vapor from being generated in the fuel after the internal combustion engine is stopped, thereby improving the startability of the internal combustion engine. An object is to provide a cooling structure for a fuel pump.

  In order to achieve the above object, the fuel pump cooling structure according to the present invention is (1) installed in the cylinder head cover so that at least one portion is located in the cylinder head cover of the internal combustion engine, and fuel is supplied to the fuel injection valve. A cooling structure for a fuel pump to be supplied, comprising oil guide means provided on an inner peripheral surface of the cylinder head cover and guiding oil scattered from the lubricated member to the inner peripheral surface of the cylinder head cover to the fuel pump. Consists of things.

  This fuel pump cooling structure has an oil guide means for guiding oil scattered from the lubricated member to the inner peripheral surface of the cylinder head cover to the fuel pump on the inner peripheral surface of the cylinder head cover. Immediately after the engine is stopped, the oil remaining on the inner peripheral surface of the cylinder head cover can be supplied to the fuel pump to prevent the temperature of the fuel pump from rising due to radiant heat from the internal combustion engine body.

  For this reason, it is possible to prevent the temperature of the fuel passing through the fuel pump from rising and to prevent vapor from being generated in the fuel. As a result, the fuel containing the vapor can be prevented from being injected together with the fuel from the fuel injection valve, and the startability of the internal combustion engine can be prevented from deteriorating.

  In the fuel pump cooling structure according to the above (1), (2) the fuel pump is inserted into the fuel pump main body and the fuel pump main body so as to reciprocate and pressurizes the fuel together with the fuel pump main body. From a high-pressure fuel pump comprising a plunger that defines a pressure chamber, and a lifter that moves the plunger in a direction in which the pressurizing chamber contracts by applying a pressing force from a drive cam attached to a camshaft to the plunger. The oil guide means is configured to guide oil to a lower portion of the fuel pump main body.

  In this fuel pump cooling structure, the oil guide means guides the oil to the lower part of the fuel pump main body. Therefore, immediately after the internal combustion engine is stopped at the time of dead soak or the like, it is close to the combustion chamber etc. Since the oil remaining on the inner peripheral surface of the cylinder head cover can be preferentially supplied to the lower part of the fuel pump body affected by radiant heat, the temperature of the fuel pump rises due to radiant heat from the internal combustion engine body. This can be further prevented.

  In the fuel pump cooling structure according to the above (2), (3) the cylinder head cover is attached so as to cover an upper portion of a cylinder head portion, and the fuel pump is attached to either the cylinder head cover or the cylinder head portion. An opening through which the main body is inserted; and a pump housing that supports the fuel pump main body on either the cylinder head cover or the cylinder head portion, and at the lower end of the opening of the pump housing, A guide portion for guiding the oil guided by the oil guide means to the lower portion of the fuel pump main body is formed.

  In this fuel pump cooling structure, a guide portion for guiding the oil guided by the oil guide means to the lower portion of the fuel pump body is formed at the lower end of the opening of the pump housing through which the fuel pump body is inserted. Therefore, the oil guided by the oil guide means can be supplied to the lower portion of the fuel pump body through the pump housing that holds the fuel pump body on the cylinder head cover or the cylinder head portion.

  For this reason, it is possible to further prevent the temperature of the fuel pump from rising due to, for example, radiant heat from the internal combustion engine body immediately after the internal combustion engine is stopped during dead soak.

  In the fuel pump cooling structure according to the above (1) to (3), (4) at least a part of the cylinder head cover is provided to be inclined from one end to the other end with respect to a horizontal plane. A fuel pump is provided at a lower portion of the cylinder head cover in the inclination direction, and the oil guide means is formed on an inner peripheral surface of the cylinder head cover and extends from a higher portion of the cylinder head cover in the inclination direction toward the fuel pump. An inclined portion that exists, and an inner peripheral surface of the cylinder head cover that constitutes the inclined portion, protrudes downward from the inner peripheral surface of the cylinder head cover, and extends from the inner peripheral side surface of the cylinder head cover toward the fuel pump. It is comprised from the extending part extended.

  This cooling structure of the fuel pump is configured such that immediately after the internal combustion engine is stopped at the time of dead soak or the like, residual oil scattered on the inner peripheral side surface and the inclined portion of the cylinder head cover protrudes downward from the inner peripheral surface of the head cover so that the cylinder head cover It can be directed to the fuel pump by the extending portion extending from the inner peripheral side toward the fuel pump, and can be guided to the fuel pump along the inclined portion of the cylinder head cover. For this reason, oil can be efficiently guided to the fuel pump, and the temperature of the fuel pump can be further prevented from rising due to radiant heat from the internal combustion engine body.

  ADVANTAGE OF THE INVENTION According to this invention, the cooling structure of the fuel pump which can prevent that a vapor | steam generate | occur | produces in a fuel after a stop of an internal combustion engine, and can improve the startability of an internal combustion engine can be provided.

1 is a diagram showing an embodiment of a fuel pump cooling structure according to the present invention, and is a schematic configuration diagram of a fuel supply system including a high-pressure fuel pump. FIG. 4 is a view showing an embodiment of a cooling structure for a fuel pump according to the present invention, and is a longitudinal section cut in the direction of arrow CC when the cylinder head cover, the valve mechanism, and the camshaft housing of FIG. 3 are integrated. It is a top view and a pump housing represents arrow DD sectional drawing of FIG. It is a figure which shows one Embodiment of the cooling structure of the fuel pump which concerns on this invention, and is a disassembled perspective view of a cylinder head cover, a valve operating mechanism, a camshaft housing, and a cylinder head main body. It is a figure which shows one Embodiment of the cooling structure of the fuel pump which concerns on this invention, and is a side view of the pump housing seen from the arrow B direction of FIG. It is a figure which shows one Embodiment of the cooling structure of the fuel pump which concerns on this invention, and is a bottom view of a cylinder head cover. It is a figure which shows one Embodiment of the cooling structure of the fuel pump which concerns on this invention, and is arrow AA sectional drawing of FIG. It is a figure which shows one Embodiment of the cooling structure of the fuel pump which concerns on this invention, and is a figure which shows the flow of oil. It is a figure which shows one Embodiment of the cooling structure of the fuel pump which concerns on this invention, and is a figure which shows the flow of oil. It is a figure which shows one Embodiment of the cooling structure of the fuel pump which concerns on this invention, and is a figure which shows the other shape of the oil guide means equivalent to the arrow AA direction sectional drawing of FIG.

Embodiments of a fuel pump cooling structure according to the present invention will be described below with reference to the drawings.
FIGS. 1-9 is a figure which shows one Embodiment of the cooling structure of the fuel pump based on this invention.
First, a schematic configuration of a fuel supply system used in an in-cylinder direct injection type (in-cylinder direct injection type) engine as an internal combustion engine to which the present invention is applied will be described.

  As shown in FIG. 1, this fuel supply system mainly includes a fuel tank 1, a feed pump 2, a pressure regulator 3, a high pressure fuel pump 4 as a fuel pump, a delivery pipe (accumulation vessel) 5, a fuel injection valve 6, a low pressure The fuel pipe 7, the high-pressure fuel pipe 8, the return pipe 9 and the like are configured.

The feed pump 2 feeds fuel from the fuel tank 1, and the pressure regulator 3 supplies the fuel in the low-pressure fuel pipe 7 to the fuel tank when the fuel pressure in the low-pressure fuel pipe 7 exceeds a predetermined pressure. By returning to 1, the fuel pressure in the low-pressure fuel pipe 7 is maintained below a predetermined pressure.
The high-pressure fuel pump 4 pressurizes the fuel sent out by the feed pump 2 and filtered by the filter 10 and stores it in the delivery pipe 5.

  The delivery pipe 5 supplies the high-pressure fuel stored therein to the fuel injection valve 6, and the fuel injection valve 6 directly supplies the high-pressure fuel in the delivery pipe 5 to each combustion chamber of the engine. It comes to inject.

  The number of the fuel injection valves 6 is the same as the number of cylinders of the engine. For example, when three fuel injection valves 6 are used as shown in the drawing, for example, a three-cylinder engine is obtained. Note that the internal combustion engine of the present embodiment may be composed of a V-type engine instead of an in-line engine. In this case, the number of cylinders in the left and right banks is, for example, 3 cylinders.

  A return pipe 9 is connected to the delivery pipe 5 via a relief valve 11. The relief valve 11 is opened when the fuel pressure in the delivery pipe 5 exceeds a predetermined pressure, and is connected to the delivery pipe 5. By returning a part of the stored fuel to the fuel tank 1 via the return pipe 9, an excessive increase in the fuel pressure in the delivery pipe 5 is prevented.

  The low pressure fuel pipe 7 is provided with a pulsation damper 12, which suppresses fuel pressure pulsation in the low pressure fuel pipe 7 when the high pressure fuel pump 4 is operated.

  As shown in FIG. 2, the high-pressure fuel pump 4 is generally a known plunger type, and mainly includes a pump unit 20, an electromagnetic spill valve 30, a check valve 40 (see FIG. 1), It includes a roller lifter 50 as a lifter.

  The pump unit 20 mainly includes an upper cylinder 21, a lower cylinder 22, a pressurizing chamber 23, and a plunger 24. The upper cylinder 21 is provided with a guide hole 21a of the plunger 24 along the vertical direction. ing. In the present embodiment, the upper cylinder 21 and the lower cylinder 22 constitute a fuel pump body.

  The pressurizing chamber 23 is provided on the upper end side of the guide hole 21 a of the upper cylinder 21, and is partitioned between the guide hole 21 a and the upper end of the plunger 24. Further, as shown in FIG. 1, the pressurizing chamber 23 is communicated with the feed pump 2 via the low pressure fuel pipe 7 and is communicated with the delivery pipe 5 via the high pressure fuel pipe 8.

A valve body (not shown) communicating with the low pressure fuel pipe 7 is attached to the back side of the upper cylinder 21 in FIG. 2, and the low pressure fuel is connected to the upper cylinder 21 via a low pressure fuel passage formed in the valve body. A passage 23 a that connects the pipe 7 and the pressurizing chamber 23 is formed.
The plunger 24 is composed of a substantially cylindrical member, and is inserted into the guide hole 21a of the upper cylinder 21 so as to be slidable up and down.

  As an operation of the pump unit 20, the plunger 24 is reciprocated vertically in the upper cylinder 21 by the rotating drive cam 18, so that the volume of the pressurizing chamber 23 is expanded or reduced.

  The electromagnetic spill valve 30 is provided above the pump unit 20 and controls communication between the low-pressure fuel pipe 7 and the pressurizing chamber 23 by controlling energization to the electromagnetic solenoid 31.

  The electromagnetic spill valve 30 mainly includes an electromagnetic solenoid 31, a bobbin 32, a core 33, an armature 34, a poppet valve 35, a seat body 36, and a compression coil spring 37.

  As an operation of the electromagnetic solenoid 31, when energization to the electromagnetic solenoid 31 is stopped, the poppet valve 35 opens the through hole of the seat body 36 by the extension restoring force of the compression coil spring 37, and the low pressure fuel pipe 7 and the pressurizing chamber 23 are communicated (valve open state).

  On the other hand, when the electromagnetic solenoid 31 is energized, the armature 34 moves toward the core 33 so as to compress the compression coil spring 37, so that the poppet valve 35 closes the through hole of the seat body 36, and the low-pressure fuel pipe 7 The pressurizing chamber 23 is shut off (closed state).

  In FIG. 1, a check valve 40 prevents the fuel discharged from the high-pressure fuel pump 4 from flowing backward, and mainly includes a valve body 41 attached to the front side of the upper cylinder 21 in FIG. The body 42 and the compression coil spring 43 are included.

  As the operation of the check valve 40, when the pressure of the fuel pumped from the pressurizing chamber 23 through the high pressure fuel passage 23b exceeds a predetermined value, the valve body 42 resists the urging force of the compression coil spring 43. 1, the check valve 40 is opened by being displaced to the right, and the high-pressure fuel pumped from the high-pressure fuel passage 23b is supplied to the delivery pipe 5 via the high-pressure fuel pipe 8. It has become so.

  The roller lifter 50 converts the rotary motion of the drive cam 18 into a linear motion and transmits it to the plunger 24 to displace the plunger 24 up and down, and mainly includes a lifter body 51, a support shaft 52, and a roller 53. It consists of

  The lifter body 51 is inserted into the guide hole 22a of the lower cylinder 22 so as to be freely reciprocally displaced along its central axis. The lifter body 51 is formed in a substantially cylindrical shape, and a partition wall 51a is provided at a substantially central portion in the vertical direction. The lifter body 51 is divided into an upper peripheral wall 51b above the partition wall 51a and a lower side The side is partitioned by the lower peripheral wall 51c.

  The lower end of the plunger 24 is in contact with the upper surface of the partition wall 51a of the lifter body 51 via a retainer 25, and a roller 53 is rotatable on the lower peripheral wall 51c of the lifter body 51 via a support shaft 52. It is supported.

  The roller 53 is rotatably supported on the outer peripheral portion of the support shaft 52 via a plurality of rollers 54, and the drive cam 18 is brought into contact with the outer peripheral surface of the roller 53 protruding outward. It has become.

  A compression coil spring 55 is compressed between the partition wall 51 a of the lifter body 51 and the upper cylinder 21, and the roller 53 is pressed against the drive cam 18 by the compression coil spring 55.

  In the high-pressure fuel pump 4, when the cam nose 18a pushes up the roller 53 of the roller lifter 50 due to the rotation of the drive cam 18 accompanying the operation of the engine, the plunger 24 of the pump unit 20 rises, and the compression coil The spring 55 is compressed and the volume of the pressurizing chamber 23 is reduced.

  On the other hand, when the cam nose 18a is separated from the roller 53 of the roller lifter 50 and the base circle contacts, the roller lifter 50 and the plunger 24 are lowered by the expansion restoring force of the compression coil spring 55, and the volume of the pressure chamber 23 is expanded.

Here, during the period in which the contact position between the drive cam 18 and the roller 53 is shifted from the apex of the cam nose 18a of the drive cam 18 to the base circle, the volume of the pressure chamber 23 is increased by lowering the plunger 24. It will be.
For this reason, by stopping the energization of the electromagnetic spill valve 30 to the electromagnetic solenoid 31 during this period, the electromagnetic spill valve 30 is opened by the expansion restoring force of the compression coil spring 37, and the poppet valve 35 is opened. When communicating with the pressure chamber 23, the fuel sent out from the feed pump 2 is sucked into the pressurizing chamber 23 through the low-pressure fuel pipe 7 (intake stroke).

On the other hand, the volume of the pressure chamber 23 is reduced by raising the plunger 24 during the period in which the contact position between the drive cam 18 and the roller 53 is shifted from the base circle of the drive cam 18 to the top of the cam nose 18a. Become.
For this reason, by energizing the electromagnetic solenoid 31 during this period, the electromagnetic spill valve 30 is closed against the elastic force of the compression coil spring 37 to close the poppet valve 35, and the low pressure fuel pipe 7, the pressurizing chamber 23, When the fuel pressure is cut off, the fuel pressure in the pressurizing chamber 23 rises, and when the fuel pressure reaches a predetermined value, the check valve 40 is opened and high pressure fuel is supplied to the delivery pipe 5 through the high pressure fuel pipe 8. It is discharged toward (pressure increase process).

Next, an engine structure to which the high pressure fuel pump 4 is attached will be described.
In FIG. 3, the cylinder head portion 60 of the engine is mounted on an upper portion of a cylinder block (not shown), a cylinder head body 61 placed on the upper portion of the cylinder block, and a seat placed on the cylinder head body 61. And a camshaft housing 62 to be configured.

  Thus, the cylinder head portion 60 has a divided structure of the cylinder head body 61 and the camshaft housing 62. Note that the cylinder head body 61 and the camshaft housing 62 may have an integral structure.

  The cylinder head body 61 is fastened to the cylinder block by a plurality of bolts (not shown). The cylinder block is a cylinder block in which a piston is slidably provided in a cylinder, and a crankcase to which a crankshaft for converting the vertical movement of the piston into a rotational movement is attached is attached to the lower part. .

  The cylinder head body 61 and the camshaft housing 62 are made of, for example, an aluminum alloy, and the cylinder head body 61 is provided with a valve operating mechanism including an intake valve, an exhaust valve, an intake camshaft, an exhaust camshaft, and the like. It is attached.

  Further, the camshaft housing 62 has an outer edge shape that substantially matches the outer edge shape of the cylinder head body 61, and includes a frame portion 63 that constitutes the outer frame of the camshaft housing 62.

  A plurality of bolt insertion holes 63a are formed in the outer peripheral edge portion of the frame portion 63 with a predetermined spacing, and a plurality of bolt insertion holes 61a are formed in the outer peripheral edge portion of the cylinder head body 61 with a predetermined spacing. A bolt (not shown) is inserted into the bolt insertion holes 63a and 61a.

  The frame portion 63 is provided with a plurality of bearing portions 64 to 68, the bearing portions 64 to 67 are provided between the frame portions 63, and the bearing portion 68 is one end portion of the frame portion 63. Is provided.

  The bearing portions 64 to 67 are formed with semi-circular intake side bearing recesses 64a, 65a, 66a, and 67a for rotatably supporting the lower side of the intake camshaft 69. Are formed with semicircular arc-shaped exhaust side bearing recesses 64b, 65b, 66b, 67b, 68a for rotatably supporting the lower side of the exhaust camshaft 70.

  Each intake camshaft 69 is provided with an intake cam 69a slidably contacting the intake valve. The intake cam 69a is slidable on an intake valve provided on the cylinder head body 61. In the present embodiment, since a pair of intake valves are provided for one cylinder, a total of six intake cams 69a are provided on the intake camshaft 69.

  Each exhaust camshaft 70 is provided with an exhaust cam 70a slidably contacting the exhaust valve. The exhaust cam 70a is slidable on an exhaust valve provided on the cylinder head body 61. Since a pair of exhaust valves are provided for one cylinder, a total of six exhaust cams 70a are provided on the exhaust camshaft 70.

  Further, bearing caps 71 to 75 and a pump housing 77 are fastened to the bearing portions 64 to 68 by bolts (not shown), and the bearing caps 71, 72, 74, and 75 are combined with the bearing portions 64 to 67. The intake camshaft 69 is rotatably supported, and the bearing caps 71, 72, 73 and the pump housing 77 support the exhaust camshaft 70 together with the bearing portions 64-68.

  As shown in FIGS. 3 and 4, the drive cam 18 is located between the bearing portion 67 and the bearing portion 68 and is attached to the exhaust camshaft 70, and the drive cam 18 is the roller 53 described above. Is in sliding contact.

  On the other hand, the pump housing 77 includes a pump housing main body 78 and mounting legs 79 and 80 which are integrally provided with the pump housing main body 78 and fastened to bearings 67 and 68 by bolts (not shown). The mounting legs 79 and 80 are formed with bolt insertion holes 79a and 80a through which fastening bolts are inserted.

  The pump housing body 78 is formed with an opening 78a that penetrates in the thickness direction of the pump housing body 78. When the pump housing 77 is attached to the camshaft housing 62, the opening 78a is formed. It is formed at a position facing the drive cam 18.

  The lower cylinder 22 of the high-pressure fuel pump 4 is inserted into the opening 78a. As shown in FIG. 2, the upper cylinder 21 is formed with a mounting portion 21b that protrudes radially outward from the outer peripheral portion of the upper cylinder 21, and a bolt insertion hole 21c is formed in the mounting portion 21b. ing.

  A mounting portion 22b is formed at the upper end of the lower cylinder 22 so as to project radially outward from the outer peripheral portion of the lower cylinder 22, and a bolt insertion hole 22c is formed in the mounting portion 22b.

  Bolt screw holes 78b are formed in the pump housing main body 78, and bolts 81 are screwed into the bolt screw holes 78b. Accordingly, the bolt 81 is screwed into the bolt screw hole 78b through the bolt insertion holes 21c and 22c, and the mounting portions 21b and 22b are placed on the upper end of the pump housing body 78, whereby the high-pressure fuel pump 4 is The pump housing 77 is attached.

  On the other hand, as shown in FIGS. 2 and 3, a cylinder head cover 91 is attached to the camshaft housing 62, and a frame portion 63 of the camshaft housing 62 is attached to the outer periphery of the cylinder head cover 91. Bolt insertion holes 91 a are formed which are positioned in bolt insertion holes 63 a formed in the outer peripheral edge portion. A plurality of bolt insertion holes 91 a are provided separately from the outer peripheral edge of the cylinder head cover 91.

  For this reason, the cylinder head cover 91 and the camshaft housing 62 are integrally fastened to the cylinder head main body 61 by screwing bolts (not shown) into the bolt insertion holes 62a, 63a, 61a through the bolt insertion holes 91a.

  A through hole 91b is formed at one end of the cylinder head cover 91. The through hole 91b communicates with an opening 78a of the pump housing body 78 of the pump housing 77, and the high pressure fuel pump 4 is inserted into the through hole 91b. It is designed to be inserted. For this reason, the lower cylinder 22 which is a part of the high-pressure fuel pump 4 is positioned inside the cylinder head cover 91 and is installed in the cylinder head cover 91 via the pump housing 77.

  As shown in FIGS. 3 and 5, an oil shower pipe 92 is attached in the cylinder head cover 91. The oil shower pipe 92 has a plurality of injection holes for supplying oil to the intake cam 69a and the exhaust cam 70a. 92a is formed. Note that twelve injection holes 92a are formed in the oil shower pipe 92 corresponding to the number of intake cams 69a and exhaust cams 70a.

The oil shower pipe 92 is supplied with oil from an oil pump (not shown) via a cylinder block, a cylinder head main body 61 and a camshaft housing 62, and an intake cam 69a and an exhaust cam 70a from an injection hole 92a. By injecting the oil, the sliding surfaces of the intake cam 69a and the intake valve are lubricated, and the sliding surfaces of the exhaust cam 70a and the exhaust valve are lubricated.
An oil pump (not shown) is a known oil pump that transmits power from the crankshaft when the engine is operating. In the present embodiment, the intake cam 69a and the exhaust cam 70a constitute a lubricated member.

In addition, the engine of the present embodiment is generally installed with an inclination with respect to the horizontal plane. Therefore, as shown in FIG. 2, the upper surface of the cylinder head cover 91 is also inclined with respect to the horizontal plane.
That is, the cylinder head cover 91 according to the present embodiment is provided so as to be inclined from the left end, which is one end portion, to the right end, which is the other end portion, with respect to the horizontal plane. It is provided in a low part. For this reason, the high-pressure fuel pump 4 is also installed at a lower portion of the cylinder head cover 91 in the inclination direction.

  The inclined surface of the cylinder head cover 91 from the left end, which is one end with respect to the horizontal plane, to the high-pressure fuel pump 4 forms an inclined portion 93, and a taper 93a is formed downstream of the inclined portion 93 in the inclined direction. The lower part of the lower cylinder 22 is located on the extension line L of the taper surface of the taper 93a.

  As shown in FIGS. 2 and 4, a taper 78c as a guide portion is formed at the lower end of the opening 78a of the pump housing 77. The taper 78c is collinear with the extension line L of the taper 93a. It is formed on the taper surface. That is, the lower end portion of the opening 78a is provided between the mounting legs 79 and 80, and an oil circulation path is secured in the taper 78c.

  On the other hand, as shown in FIGS. 2, 5, and 6, the inclined portion 93 of the cylinder head cover 91 is formed with five ribs 94 as extending portions, and the rib 94 is an inclined portion of the cylinder head cover 91. 93 protrudes from the lower side 93 toward the camshaft housing 62, and extends from the inner peripheral side surface 91 c of the cylinder head cover 91 toward the high-pressure fuel pump 4. The rib 94 and the inclined portion 93 guide the oil scattered on the inner peripheral surface of the cylinder head cover 91 toward the high-pressure fuel pump 4, and the inclined portion 93 and the rib 94 constitute an oil guide means. Yes.

Next, the operation will be described.
During operation of the engine, lubricating oil is supplied from the oil pump to the oil shower pipe 92. The oil is injected from the injection hole 92a to the intake cam 69a and the exhaust cam 70a, thereby lubricating the sliding surfaces of the intake cam 69a and the intake valve and lubricating the exhaust cam 70a and the sliding surfaces of the exhaust valve. Is done.

  On the other hand, the oil injected into the intake cam 69a and the exhaust cam 70a is scattered on the inner peripheral surface of the cylinder head cover 91 by the centrifugal force of the intake cam 69a as shown by the arrow a in FIG. The cylinder head cover 91 is scattered on the inner peripheral side surface 91 c and the inclined portion 93.

  In the present embodiment, the cylinder head cover 91 is provided so as to be inclined from one end to the other end with respect to the horizontal plane, and the high-pressure fuel pump 4 is provided in a lower portion of the cylinder head cover 91 in the inclination direction. The cylinder head cover 91 is formed on the inner peripheral surface of the cylinder head cover 91, extending from a portion in the tilt direction of the cylinder head cover 91 toward the high-pressure fuel pump, and the inner peripheral surface of the cylinder head cover 91 constituting the inclined portion 93. A plurality of ribs 94 that protrude downward from the inner peripheral surface of 91 and extend from the inner peripheral side surface 91 c of the cylinder head cover 91 toward the high-pressure fuel pump 4 are provided.

  Further, a taper 78c for guiding oil guided by the inclined portion 93 and the rib 94 to the lower portion of the lower cylinder 22 is formed at the lower end portion of the opening 78a of the pump housing 77 through which the lower cylinder 22 of the high-pressure fuel pump 4 is inserted. The taper 78c is positioned on the extension line L of the taper surface of the taper 93a of the inclined portion 93.

Therefore, the oil scattered on the inner peripheral side surface 91c of the cylinder head cover 91 and the inclined portion 93 is collected between the ribs 94 and directed to the high-pressure fuel pump 4 by the ribs 94, and the inclined portion 93 of the cylinder head cover 91 inclined. Can be guided along the taper 78c of the pump housing 77 to the lower part of the lower cylinder 22 of the high-pressure fuel pump 4 (see arrows b in FIGS. 7 and 8).
For this reason, the high-pressure fuel pump 4 can be always cooled with oil, and the temperature of the oil flowing in the high-pressure fuel pump 4 can be prevented from excessively rising.

  On the other hand, in a state where the engine is immediately stopped from a high load operation state, that is, at the time of so-called dead soak, the high pressure fuel is generated by radiant heat due to the temperature rise of the cylinder head portion 60 and the cylinder block due to the stop of the engine cooling system or the like. The pump temperature will rise.

  That is, since the cylinder block and the cylinder head part 60 have a high-temperature combustion chamber, the cylinder head part 60 and the cylinder block become hot at the time of dead soak, and the temperature of the high-pressure fuel pump is radiated by radiant heat from the cylinder head part 60 and the cylinder block. Will rise.

  In the present embodiment, at the time of dead soaking, as shown by an arrow b in FIG. 7, the oil remaining on the inner peripheral surface of the cylinder head cover 91 is most affected by the radiant heat by the inclined portion 93 and the rib 94. The fuel pump 4 can be preferentially supplied to the lower part of the lower cylinder 22 of the fuel pump 4.

  That is, the drive of the oil pump is stopped when the engine is stopped, but the oil scattered from the intake cam 69a to the inner peripheral surface of the cylinder head cover 91 immediately before the engine is stopped is guided by the rib 94 immediately after the engine is stopped. It is guided to the lower part of the lower cylinder 22 of the high-pressure fuel pump 4 through the inclined part 93 that is inclined.

  And since oil can be efficiently guided to the lower part of the lower cylinder 22 in this way, it is possible to prevent the temperature of the lower cylinder 22 from rising due to radiant heat from the cylinder head part 60 and the cylinder block.

  In the present embodiment, since the cylinder head body 61 is made of a material having good heat dissipation such as an aluminum alloy, the cylinder head body 61 is directed to the lower cylinder 22 by the rib 94 and flows along the inclined portion 93. The temperature of the oil can be lowered. For this reason, low temperature oil can be supplied to the lower cylinder 22, and it can prevent further that the temperature of the lower cylinder 22 rises.

  Therefore, it is possible to prevent the temperature of the fuel passing through the high-pressure fuel pump 4 from rising, and it is possible to prevent vapor from being generated in the fuel. As a result, it is possible to prevent the fuel containing vapor from being injected together with the fuel from the fuel injection valve 6, and to prevent the startability of the engine from deteriorating.

  The pump housing 77 of the present embodiment is integrally provided with mounting legs 79 and 80 and a pump housing main body 78 having an opening 78a. However, the pump housing 77 is attached to the pump housing main body 78 having the opening 78a. The leg portions 79 and 80 may be provided separately, and the pump housing main body 78 and the mounting leg portions 79 and 80 may be integrated by bolting or the like. Even in this case, it goes without saying that the taper 78c is formed at the bottom of the opening 78a.

  In this embodiment, the pump housing 77 is attached to the camshaft housing 62, but the pump housing 77 may be attached to the cylinder head cover 91.

  Further, in the present embodiment, the rib 94 is provided on the inclined portion 93 as the oil guiding means, but instead of the rib 94, as shown in FIG. 9, the groove portion 101 is formed in a portion of the cylinder head cover 91 constituting the inclined portion. May be formed.

  That is, a groove portion 101 extending from the inner peripheral side surface 91 c of the cylinder head cover 91 toward the high-pressure fuel pump 4 is formed on the inner peripheral surface of the cylinder head cover 91, and the inner peripheral upper surface of the groove portion 101, that is, the inner side of the cylinder head cover 91 The circumferential upper surface is composed of an inclined portion 101a, and the oil scattered on the inner peripheral surface of the cylinder head cover 91 is guided toward the high-pressure fuel pump 4 by the inclined portion 101a of the groove portion 101 and the inner wall surface 101b of the groove portion 101. do it. In this case, the groove portion 101 constitutes an oil guide means.

  Moreover, in this Embodiment, although the fuel pump is comprised from the high pressure fuel pump 4, you may comprise not only this but a pressure regulator. That is, the pressure regulator 3 may be installed at the position of the high pressure fuel pump 4 instead of the high pressure fuel pump 4.

  The embodiment disclosed this time is illustrative in all respects and is not limited to this embodiment. The scope of the present invention is shown not by the above description of the embodiments but by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

  As described above, the fuel pump cooling structure according to the present invention has the effect of preventing the generation of vapor in the fuel after the internal combustion engine is stopped and improving the startability of the internal combustion engine. It is installed in a cylinder head cover of an internal combustion engine and is useful as a cooling structure for a fuel pump that supplies fuel to a fuel injection valve.

4 High-pressure fuel pump (fuel pump)
6 Fuel injection valve 21 Upper cylinder (fuel pump body)
22 Lower cylinder (Fuel pump body)
23 Pressurizing chamber 24 Plunger 50 Roller lifter (lifter)
60 Cylinder head 69a Intake cam (lubricated member)
70a Exhaust cam (lubricated member)
77 Pump housing 78a Opening 78c Taper (guide part)
91 Cylinder head cover 91c Inner peripheral side surface 93 Inclined portion (oil guide means)
94 Rib (oil guide means, extension)
101 Groove (oil guide means)

Claims (4)

A cooling structure for a fuel pump, which is installed in the cylinder head cover so that at least one part is located in a cylinder head cover of an internal combustion engine and supplies fuel to a fuel injection valve;
A fuel pump cooling structure comprising oil guide means provided on the inner peripheral surface of the cylinder head cover and guiding oil scattered from the lubricated member to the inner peripheral surface of the cylinder head cover to the fuel pump. The fuel pump includes a fuel pump main body, a plunger that is reciprocally inserted into the fuel pump main body to form a pressurizing chamber that pressurizes fuel together with the fuel pump main body, and a drive cam attached to a camshaft. A high-pressure fuel pump including a lifter that moves the plunger in a direction in which the pressurizing chamber is contracted by applying a pressing force from the plunger to the plunger,
2. The fuel pump cooling structure according to claim 1, wherein the oil guide means guides oil to a lower portion of the fuel pump main body. The cylinder head cover is attached so as to cover an upper portion of a cylinder head portion, and has an opening through which the fuel pump main body is inserted in either the cylinder head cover or the cylinder head portion. A pump housing supported on either the cylinder head cover or the cylinder head portion;
3. The fuel pump according to claim 2, wherein the pump housing has a guide portion that guides oil guided by the oil guide means to a lower portion of the fuel pump body at a lower end portion of the opening. Cooling structure. At least a part of the cylinder head cover is provided to be inclined from one end to the other end with respect to a horizontal plane, and the fuel pump is provided at a lower portion in the inclination direction of the cylinder head cover.
The oil guide means is formed on an inner peripheral surface of the cylinder head cover, and extends from the high portion in the tilt direction of the cylinder head cover toward the fuel pump, and the cylinder head cover that constitutes the tilt portion. An inner peripheral surface is formed of an extending portion that projects downward from the inner peripheral surface of the cylinder head cover and extends from the inner peripheral side surface of the cylinder head cover toward the fuel pump. The cooling structure for a fuel pump according to any one of claims 1 to 3.

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