WO2004063559A1 - Fuel feed pump - Google Patents

Abstract

A fuel feed pump simple in construction, easy to produce, and capable of efficiently pressurizing a high flow rate of fuel. The fuel feed pump (50) comprises a housing (52), a plunger barrel (53), a fuel-pressurizing plunger (54) installed for lifting and lower movement in the plunger barrel, a cam (60) rotatably installed below the plunger, a tappet structure (6) installed between the cam (60) and the plunger (54) for transmitting the turning force, serving as a lifting force, from the cam shaft (3) to the plunger (54), and a return spring (68) installed between the tappet structure (6) and the plunger barrel (53) for imparting a lowering force to the plunger (54), wherein the plunger barrel (53) has a projection (53a) for supporting the upper end of the return spring (68).

Description

Fuel supply pump Technical field

 The present invention relates to a fuel supply pump. In particular, the present invention relates to a fuel supply pump suitable for an intensified piston-accumulated fuel injection device (APCRS) that requires a large flow rate of pressurized fuel. Background art

 As shown in FIG. 16, a conventional fuel supply pump 250 has a pump housing 252 having a cylindrical space that opens vertically, and a plunger mounted in an upper opening of the pump housing 255. Barrel 25 3, plunger 25 3 and plunger 25 4 arranged to be able to move up and down in cylindrical space to pressurize fuel, and rotatably arranged below plunger 25 4 And a cam 260 rotatably integrated with a cam shaft 3 (not shown) inserted in the pump housing 25 2 in the front-rear direction, and disposed between the cam 260 and the plunger 25 54. And a tap structure 206 for transmitting the rotational force of the camshaft 3 to the plunger 254 as an ascending force, and the tut structure 206 and the plunger barrel 253. To attach the lowering force to the plunger 2 5 4 And the return spring 2 6 8, was equipped with.

Such a conventional fuel supply pump 250 is disclosed in Japanese Patent Application Laid-Open Nos. 2001-310730 and 2000-221210. When the camshaft 3 rotates by driving an engine (not shown), the cam 260 moves up and down, and the plunger 255 moves up and down via the tut structure 206. Met. Therefore, the fuel is sucked into the pump chamber via the suction valve by the lowering of the plunger 254, while the fuel in the pump chamber is added by the rising of the plunger 254. The pump was pressurized and discharged from a pump chamber to a pressure accumulating chamber (not shown) via a discharge valve.

 However, in such a fuel supply pump, a projection portion 25a for supporting the upper end of the return spring 268 is provided on the inner peripheral surface of the pump housing 252. For this reason, when assembling the fuel supply pump 250, avoid such a protrusion 25a from the housing of the pump housing 252, and from above, the plunger barrel 253 and the plunger 25 I had to buy 4. On the other hand, with respect to the return spring 268 ゃ tappet structure 206, the floor plug 280 formed below the pump housing 252 is formed so as to avoid such projections 252 a. I had to enter. However, the conventional fuel supply pump has a problem that the assembly operation is complicated and it is not easy to reduce the manufacturing cost.

 Further, as disclosed in JP-A-56-93939 and Japanese Patent No. 2857076, in a diesel engine, high-pressure fuel is efficiently injected to achieve high efficiency. In order to increase output, improve fuel efficiency, reduce black smoke, etc., increase the fuel from the accumulator type fuel injection device (CRS: Common Rail System) using an accumulator (common rail), and increase the fuel from the accumulator. An accumulator type fuel injection device used under pressure has been proposed.

 However, in such a fuel supply pump 250, a predetermined lubrication mechanism (not shown) is provided on the tappet structure, or a seal mounted between the pump housing 252 and the plunger barrel 253 is provided. Although it is intended to supply a relatively large flow rate of fuel to the accumulator by making the ring 25 2 b into a predetermined shape, it is necessary to further increase the output of the diesel engine. However, the degree of pressurization and fuel flow were still insufficient.

Accordingly, the inventors of the present invention have conducted intensive studies, and as a result, instead of providing a protrusion for supporting the upper end of the return spring on the inner peripheral surface of the pump housing, the plunger barrel is provided with a protrusion above the return spring. It has been found that the above problem can be solved by providing a projection for supporting the end. That is, an object of the present invention is to provide a fuel supply pump that has a simple structure, is easy to manufacture, and can efficiently pressurize a large amount of fuel. Disclosure of the invention

 [1] According to the present invention, a pump housing having a vertically open cylindrical space, a plunger barrel mounted in an upper opening of the pump housing, and a vertically movable plunger barrel and a cylindrical space. A plunger that is disposed and pressurizes the fuel; a cam that is rotatably disposed below the plunger and that is integrated with a cam shaft that is passed through a pump housing. And a tut structure that transmits the vertical movement from the cam due to the rotation of the camshaft to the plunger as an ascending force, and is mounted between the tut structure and the plunger barrel, and descends to the plunger. A fuel supply pump comprising: a return spring for applying force; and a plunger barrel supporting an upper end of the return spring. A fuel supply pump having a protruding portion is provided to solve the above-mentioned problem.

 That is, with this configuration, the protrusion for supporting the upper end of the return spring from the inner peripheral surface of the pump housing can be omitted. Therefore, since there is no obstacle on the inner peripheral surface of the pump housing, insert a temporary assembly of the tappet structure, plunger barrel, plunger, and other elements from above the pump housing into the cylindrical space of the housing. be able to. Further, a bottom plug for inserting the tut structure can be omitted. Therefore, it is possible to provide a fuel supply pump having a simple structure and easy to manufacture.

Also, since there is no obstacle on the inner peripheral surface of the pump housing, the inner peripheral surface of the pump housing can be machined more precisely and easily than before. Therefore, it is possible to set the rotational speed of the force shaft higher, and to provide a fuel supply pump capable of sufficiently pressurizing a large amount of fuel and supplying the fuel to the accumulator. [2] In configuring the fuel supply pump of the present invention, it is preferable that the plunger barrel has a large-diameter portion for restricting the radial movement of the return spring. With such a configuration, it is possible to omit a projection for restricting the radial movement of the return spring, which is conventionally provided on the inner peripheral surface of the pump housing, and another restricting member.

 Therefore, it is possible to provide a fuel supply pump with a reduced number of parts, a simpler structure, and easy manufacture.

[3] In configuring the fuel supply pump of the present invention, it is preferable that the projection of the plunger barrel has an outer peripheral surface that fits the peripheral surface of the cylindrical space of the pump housing.

 With this configuration, the radial movement of the plunger barrel in the pump housing can be easily and accurately regulated.

[4] In configuring the fuel supply pump of the present invention, it is preferable that the plunger barrel has a seal ring receiving portion on the outer peripheral surface of the projection.

 With this configuration, the radial movement of the plunger barrel in the pump housing can be more effectively restricted.

[5] In configuring the fuel supply pump of the present invention, a spring sheet having an opening through which a plunger passes is provided between the return spring and the tap structure, and the spring is provided. It is preferable to provide a spring holding portion for restricting the downward movement of the return spring on the outer peripheral portion of the sheet. With this configuration, the resilience of the return spring can be effectively applied to the plunger via the spring sheet as a downward force.

[6] Further, in constituting the fuel supply pump of the present invention, the tut structure includes a cylindrical shell having an outer peripheral surface that fits the outer peripheral surface of the cylindrical space of the pump housing. Further, it is preferable that a protrusion for restricting the radial movement of the return spring be provided on the inner surface of the shell.

 With this configuration, the roller body itself does not need to have a function of restricting the radial movement of the spring seat, and the structure of the roller body can be simplified.

[7] Further, in configuring the fuel supply pump of the present invention, it is necessary to pressurize a fuel having a flow rate per unit time of 500 to 1,500 liters to a value of 50 MPa or more. Preferably, it is used in a pressure accumulating fuel injection device.

 By using such a pressure-accumulation type fuel injection device, it is possible to easily pressurize a large flow rate of fuel, thereby increasing the combustion efficiency of the fuel injection device, further increasing the output of the diesel engine, and improving fuel efficiency. , Black smoke can be reduced. BRIEF DESCRIPTION OF THE FIGURES

 FIG. 1 is a side view of a fuel supply pump according to the present invention having a partial cutout.

 FIG. 2 is a cross-sectional view of the fuel supply pump of the present invention.

 FIG. 3 is a perspective view and a sectional view of the housing.

 FIG. 4 is a diagram illustrating a plunger barrel, a fuel intake valve, and a fuel discharge valve.

 FIG. 5 is a perspective view and a side view of the plunger.

 FIG. 6 is a perspective view, a plan view, and a cross-sectional view of the spring seat.

 FIG. 7 is a diagram provided for explaining the tut structure.

 FIG. 8 is a diagram provided to explain a roller body.

 FIG. 9 is a perspective view of the tappet structure.

 FIG. 10 is a sectional view of the fuel intake valve.

 FIG. 11 is a sectional view of the fuel intake valve.

FIG. 12 is a diagram provided to describe a system of a pressure accumulating fuel injection device (APCRS) of a piston pressure increasing system. FIG. 13 is a view provided to explain the structure of a pressure accumulating fuel injection device (APCRS) of the piston pressure increasing type.

 FIG. 14 is a diagram carefully illustrating a method of increasing fuel pressure by a piston pressure-accumulating pressure accumulating fuel injection device (APCRS).

 FIG. 15 is a diagram provided for explaining a high-pressure fuel injection timing chart.

 FIG. 16 is a diagram provided to explain the structure of a conventional fuel supply pump. BEST MODE FOR CARRYING OUT THE INVENTION

 Hereinafter, embodiments of the fuel supply pump of the present invention will be specifically described with reference to the drawings as appropriate.

1. Basic form of fuel supply pump

 As shown in FIGS. 1 and 2, the present embodiment includes a pump housing 52 having a cylindrical space that opens vertically, a plunger barrel 53 mounted in an upper opening of the pump housing 52, A plunger 54, which is vertically movable in the plunger barrel 53 and the cylindrical space and pressurizes the fuel, is rotatably arranged below the plunger 54, and is passed through the pump housing 52. The cam 60 integrated with the camshaft 3 and the cam 60 and the plunger 54 are arranged between the cam 60 and the plunger 54. The vertical movement of the cam 60 due to the rotation of the cam shaft is transmitted to the plunger 54 as a lifting force. And a return spring 68 attached between the tut structure 6 and the plunger barrel 53 to apply a downward force to the plunger 54. Feed pump 5 0 A.

 The fuel supply pump 50 according to the present embodiment is characterized in that the plunger barrel 53 has a projection 53a for supporting the upper end of the return spring 68.

Hereinafter, the fuel supply pump 50 will be described in detail by dividing it into components and the like. (1) Pump housing

 As shown in FIGS. 1 and 2, the pump housing 52 houses a plunger barrel 53, a plunger 54, a tappet structure 6, and a cam 60, and also defines a fuel compression chamber 74. It is a housing formed. Therefore, as shown in FIGS. 3 (a) and (b), the pump housing 52 has a shaft through-hole 92a opening in the left-right direction and cylindrical spaces 92b, 922 opening in the vertical direction. It is preferable that each has c.

 Further, as shown in FIG. 3 (b), it is preferable that the pump housing 52 further have through holes 97, 98 which open in the side direction of the cylindrical spaces 92b, 92c. . That is, the through holes 97 and 98 are formed by, for example, stepped holes composed of three large, medium and small holes 97 a to 97 c and 98 a to 98 c having different diameters. Is preferred. Therefore, the guide pins are press-fitted into the holes 97a and 98a, and positioning accuracy of the guide pins can be secured. The holes 97b and 98b guide the tip of the guide pin into the holes 97c and 98c in order to press-fit the tip of the guide pin into the holes 97c and 98c. It is preferable that the holes 97a and 98a are configured as screw portions into which guide pins are screwed. Therefore, the guide pin can be press-fitted by screwing.

 In addition, since a projection for supporting the upper end of the return spring 68 is provided on the plunger barrel 53 described later, the inner circumference of the cylindrical spaces 9 2 b and 9 2 c in the pump housing 52 is provided. The projection on the surface can be omitted.

Therefore, the inner peripheral surface of the pump housing 52 can be easily processed, and can be precisely processed. Thereby, even when the camshaft 3 rotates at a high speed, the vibration due to the rotation is effectively suppressed, and the rotation speed of the camshaft 3 can be set higher than before. In addition, since the camshaft 3 rotates at high speed and is able to supply a sufficiently pressurized large flow of fuel to the pressure accumulator, it is possible to increase the output of the diesel engine, improve fuel efficiency, reduce black smoke, etc. become. Further, since the installation of the bottom plug for inserting the tappet structure or the like can be omitted, the structure can be simplified. Furthermore, it is only necessary to temporarily insert the elements such as the tappet structure 6, the plunger barrel 52, the plunger 54, etc. from above the pump housing 52 into the cylindrical spaces 9 2b, 9 2c of the housing. Since the fuel supply pump 50 can be assembled, the production cost can be significantly reduced.

 Preferably, the radial movement of the return spring 68 is regulated by the plunger barrel 53. The reason for this is that the spring receiving portion for restricting the radial movement of the return spring in the pump housing, which is conventionally required, can be omitted. Therefore, the inner peripheral surface of the pump housing can be processed more easily and accurately, and the rotation speed of the cam shaft can be set higher.

(2) Plunger barrel

 As shown in FIGS. 1 and 2, the plunger barrel 53 is a casing for supporting the plunger 54, and the plunger 54 is used to pressurize a large amount of fuel to a high pressure. Pump chamber) This is an element that constitutes a part of 4). Therefore, the plunger barrel 53 is attached to the upper openings of the cylindrical spaces 92b, 92c of the pump housing 52. As shown in FIG. 2, a fuel tank (see FIG. 2) is provided between the outer peripheral surface of the plunger barrel 53 and the inner peripheral surface of the pump housing 52 (the peripheral surfaces of the cylindrical spaces 92 b and 92 c). (Not shown), and a fuel compression chamber 74 is provided for compressing the fuel.

 Further, the plunger barrel 53 has a projection 53 a for supporting the upper end of the return spring 68. The reason is that the upper end of the return spring 68 is supported by the projection 53 a of the plunger barrel 53, and the upward movement of the return spring 68 is restricted on the inner peripheral surface of the pump housing 52. This is because the protrusion for the second step can be omitted.

Further, as shown in FIG. 2, the plunger barrel 53 preferably has a large-diameter portion 53 b for restricting the radial movement of the return spring 68. The reason for this is that a projection for restricting the radial movement of the return spring 68 is provided on the peripheral surface of the pump housing 52, or the radial movement of the return spring 68 is restricted. This is because it is not necessary to provide another member for controlling the pressure between the pump housing 52 and the return spring 68.

 Further, in the plunger barrel 53, it is preferable that the projection 53 a has an outer peripheral surface that fits the outer peripheral surface of the cylindrical space of the pump housing 52. The reason for this is that the radial movement of the plunger barrel 53 inside the pump housing 52 can be restricted.

 Further, in the plunger barrel 53, as shown in FIG. 4, it is preferable to have a seal ring receiving portion 53c on the outer peripheral surface of the projecting portion 53a. The reason for this is that the radial movement of the plunger barrel 53 inside the pump housing 52 can be regulated more effectively.

 Regarding the form of the plunger barrel 53, when the type of the fuel supply pump in which the plunger barrel 53 is provided is an in-line type or a radial type, the form of the plunger barrel is appropriately adjusted so as to correspond to each type. Can be changed.

(3) Plunger

 As shown in FIGS. 1 and 2, the plunger 54 is a main element for pressurizing the fuel in the fuel compression chamber 74 in the plunger barrel 53 to a high pressure. Therefore, the plunger 54 is arranged to be able to move up and down in the plunger barrel 53 attached to the cylindrical spaces 92b and 92c of the pump housing 52, respectively. Further, as shown in FIGS. 4 and 5, the fuel cell system has a pressurizing section 54 a for entering and exiting the fuel compression chamber 74.

The pressurizing portion 54a is designed to be smaller than the diameter of the plunger barrel 53, and when it moves to the top dead center, the pressurizing portion 54a and the discharge valve 79 Preferably, a gap is formed between them. The reason is that even after the plunger 54 is driven at a high speed to pressurize a large amount of fuel, the pressurizing section 54a does not block the entrance of the discharge pulp 79, This is to smoothly pump the fuel. The plunger 54 is formed in a round bar shape as a whole so that it can be smoothly driven at a high speed in the plunger barrel 53, and has a flange 5 at an end opposite to the pressurizing section 54a. Has 5 In other words, it is preferable that a collar portion 55 for locking is provided on the outer peripheral surface of the distal end portion (lower end portion) of the cylindrical plunger 54. The reason for this is that with such a configuration, the plunger can be easily and reliably fixed to the opening 15 provided in the plunger mounting portion 14. Further, as shown in FIG. 2, the plunger 54 is constantly urged to the cam side by a plunger return spring 68, and rises in response to the rotation of the cam 60, thereby moving up the fuel compression chamber. Preferably, it is configured to pressurize the fuel in 74.

 In the fuel supply pump according to the present embodiment, it is preferable that the cam and the plunger are driven at high speed to pressurize a large amount of fuel. Specifically, it is preferable to set the rotation speed of the cam to a value within the range of 1,500 to 4,000 rpm. Further, it is preferable that the cam rotation speed be a value within a range of 1 to 5 times the engine rotation speed in consideration of the gear ratio.

(4) Fuel compression chamber

 The fuel compression chamber 74 is a small chamber formed in the plunger barrel 53 together with the plunger 54 as shown in FIG. Therefore, in the fuel compression chamber 74, the fuel that has quantitatively flowed in through the fuel supply valve 73 can be efficiently and massively pressurized by driving the plunger 54 at high speed. Even in such a case where the plunger 54 is driven at a high speed, a fuel passage hole is provided in each of a spring seat and a roller body to be described later so that the lubricating fuel does not obstruct the plunger 54. It is preferable that the fuel passage holes communicate with each other.

 On the other hand, after the pressurization by the plunger 54 is completed, the pressurized fuel is supplied to the common rail (not shown) via the fuel discharge parfuff 9.

(5) Spring seat FIG. 6A is a perspective view of the spring seat 10. FIG. 6 (b) is a plan view of the spring seat 10, and FIG. 6 (c) is a cross-sectional view of the spring seat 10 shown in FIG. 16 (a).

 The spring seat 10 includes a spring holding portion 12 for holding a spring used when pulling down the plunger 54 of the fuel supply pump 50, and a plunger mounting portion 1 for locking the plunger. It is preferable to have a through hole 16 through which the lubricating oil or the lubricating fuel passes around the plunger mounting portion 14. In the spring seat 10, it is preferable that an opening 15 for penetrating the plunger 54 is provided at the center of the plunger mounting portion 14. The reason for this is that with this configuration, the lubricating oil or lubricating fuel can freely flow through the spring seat 10, and there are few factors that hinder high-speed driving of the plunger 54. That's why.

(6) Touch structure

 Next, the tappet structure will be described with reference to the drawings. Here, FIG. 7 is a diagram for explaining a tappet structure, FIG. 8 is a diagram for explaining a roller body, and FIG. 9 is a perspective view of the tappet structure. .

As shown in FIGS. 7A to 7C, the tappet structure 6 includes a roller 29 having a pin portion and a roller portion integrated, a roller body 28 receiving the roller 29, It is composed of a cylindrical shell 27 arranged so as to surround the roller 29 and the roller body 28, and by the rotational motion of the camshaft 3 and the force 60 connected thereto as shown in FIG. It is preferable to be configured to move up and down. The reason for this is that with this configuration, the number of parts can be reduced, and lubrication between the pin and the roller is not required as in the conventional case, and the roller can be rotated at high speed. Therefore, since the rotation speed of the camshaft 3 can be further increased, a large flow rate of fuel that has been sufficiently pressurized can be supplied to the accumulator. Further, as shown in FIGS. 7A to 7C, the roller body 28 has a body 30 and is mounted in the shell 27. And the body body 30 is low A roller receiving portion 30a having an inner peripheral surface that matches the outer peripheral surface of the roller 29 is provided. As shown in FIGS. 8 (a) to 8 ( _c ), a contact portion 30 c for the plunger 54 is integrally provided at the center of the upper surface of the body 30. Further, it is preferable that a sheet receiving portion 30 d for receiving the spring seat 10 is integrally provided on a peripheral portion of the body 30.

 On the other hand, in the roller receiving portion 30a, it is preferable that a carbon coating film made of, for example, an amorphous hard carbon film is formed on the surface thereof. The reason for this is to reduce the friction on the surface of the roller receiving portion 30a, suppress the wear on the surface of the roller receiving portion 30a, and rotate the roller 29 at high speed.

 The carbon coating film preferably contains nitrogen and silicon, and the method for forming the carbon coating film is not particularly limited. However, it is preferable to use a CVD method using plasma or an ion beam.

 As shown in FIGS. 7 to 9, the roller body 28 has, for example, two fuel passage holes 3 Ob for allowing lubricating oil or fuel used for lubrication inside the fuel supply pump to pass therethrough. It is preferable to be provided around the body so as to be symmetrical with respect to the central projection 30c.

 The shell 27 is formed by a cylindrical body that is open in the vertical direction and has an outer peripheral surface that fits the peripheral surfaces of the cylindrical spaces 92 b and 92 c of the pump housing 52 shown in FIG. Is preferred. A long hole 27 a for guiding the guide pin is provided in the upper part of the peripheral wall of the shell 27, and is formed as a through hole extending in the axial direction of the seal 27. Is preferred. The reason is that, when the tappet structure 6 moves up and down, the guide pins and the elongated holes 27a cooperate, so that the operation direction of the tappet structure 6 does not deviate and the cylindrical space 9 2b, 9 2c This is to make it possible to move up and down along the axis. Also, centering of the tappet structure 6 with respect to the pump housing 52 can be performed only by inserting the outer peripheral surface of the shell 27 into the pump housing 52.

Further, it is preferable that a first protrusion 27 b is provided on the inner peripheral surface of the shell 27 as a protrusion for restricting the upward movement of the roller body 28. In addition, a projection for regulating the radial movement of the spring seat 10 is provided on the inner peripheral surface of the shell 27. Preferably, the second protrusion 27c is provided on the body. The reason for this is that it is not necessary for the mouth body 28 to have a function of restricting the radial movement of the spring sheet 10, and the shape of the roller body 28 can be simplified.

(7) Cam

 As shown in FIGS. 1 and 2, the cam 60 is a main element for changing the rotational motion of the camshaft into the vertical motion of the plunger 54 via the touch structure 6. Therefore, it is preferable that the cam 60 is rotatably held in the shaft through-hole 92 a via a bearing, and is configured to rotate by driving of the engine (camshaft 3). .

 Further, the cam 60 is located below the cylindrical spaces 92b, 92c of the pump housing 52, and two cams 60 are arranged in parallel with the camshaft 3 at a predetermined interval in the axial direction. Is preferably provided.

(8) Fuel intake valve and fuel discharge valve

 It is preferable that the fuel intake valve and the fuel discharge valve be arranged as shown in FIG. 4 and be configured as shown in FIGS. 10 to 11.

 That is, as shown in FIG. 10, the fuel intake valve 73 preferably has a valve body 19 and a valve body 20 provided with a flange portion 20b at the tip. Further, as shown in FIG. 10, the valve body 19 has a cylindrical fuel intake chamber 19a that opens downward, and a fuel intake hole 1 for sucking fuel into the fuel intake chamber 19a. Preferably 9b is provided.

 Further, the fuel discharge valve 79 also preferably has a valve body and is housed in a part of the pump housing. It is preferable that the spring is always energized in the valve closing direction by a spring, and the pressurized fuel is supplied to the common rail by opening and closing the valve.

Further, as shown in FIG. 11, the fuel intake valve 73 and the fuel discharge valve 79 are composed of a valve body 19, a valve body 20 operably mounted inside the valve body 19, and a valve body. A fuel intake chamber 19 a provided inside the body 19, a fuel intake hole 19 b, and a seat portion 23 where a part of the valve body 20 and a part of the valve body 19 are in contact with each other. Preferably, a plurality of fuel suction holes 19b are provided, and the fuel suction holes 19b are arranged non-radially with respect to the fuel suction chamber 19a.

 The reason for this is that with such a fuel intake valve, even if the flow rate per unit time is about 500 to 1,500 liters Z for the fuel supply pump, for example, it is extremely low. This is because they can be supplied accurately and quantitatively.

 Similarly, with a fuel discharge valve having such a configuration, even if the flow rate per unit time is about 500 to 1,500 liters with respect to the common rail, it is extremely accurate. This is because it can be supplied quantitatively.

(9) Lubrication system

 The lubrication system of the fuel supply pump is not particularly limited, but it is preferable to employ a fuel lubrication system that uses a part of the fuel oil as a lubricating component (lubricating oil fuel).

 The reason is that when fuel is used for lubricating the cam chamber, etc., the fuel is pressurized and the fuel is fed to the common rail. This is because there is no particular problem even if they are mixed. That is, since these are the same components, additives and the like included in the lubricating oil are not mixed with the fuel to be pumped to the common rail unlike the case where the lubricating oil is used for lubricating the cam chamber and the like. . Therefore, by adopting this fuel lubrication system, additives and the like contained in the lubricating oil are not mixed with the fuel and injected into the engine, and as a result, the exhaust gas purification performance is reduced. Disappears.

2. Accumulation type fuel injection device

The fuel supply pump of the present embodiment is a part of a pressure-accumulation type fuel injection device having the following configuration, for example, a piston pressure-accumulation type pressure-accumulation fuel injection device (APCRS) 100. It is preferable that That is, as shown in FIG. 12, the fuel supply pump 103 includes a fuel tank 102, a feed pump (low-pressure pump) 104 for supplying fuel to the fuel tank 102, A fuel supply pump (high-pressure pump) 103, a common rail 106 as an accumulator for accumulating the fuel pumped from the fuel supply pump 103, and a piston intensifier (intensifier piston) ) And fuel injection device 110.

(1) Feed pump and fuel supply pump

 As shown in FIG. 12, the feed pump 104 pumps the fuel (light oil) in the fuel tank 102 to the fuel supply pump 103, and feed pump 104 and fuel It is preferable that a filter 105 is interposed between the supply pump 103 and the supply pump 103. The feed pump 104 has a gear pump structure, is attached to the end of the force shaft, and is directly connected to the cam shaft or driven through an appropriate gear ratio through driving of the gear. preferable.

 Further, it is preferable that the fuel pumped from the feed pump 104 through the filter 105 is further supplied to the fuel supply pump 103 via a known proportional control valve (FMU). .

 The proportional control valve can control fuel supplied to a suction valve (not shown) of the fuel supply pump 103 under the control of an electronic control unit (ECU) described later, for example.

 The fuel supplied from the feed pump 104 is pressure-fed to a proportional control valve and a fuel supply pump 103, and an overflow valve (parallel to the proportional control valve) is provided. It is preferable that the fuel tank 102 be returned to the fuel tank 102 via OFV). Further, it is preferable that a part of the fuel is pressure-fed to a bearing (not shown) of the fuel supply pump 103 via an overflow valve, and is used as a fuel lubricating oil for the bearing.

The fuel supply pump 103 is, as described above, a device for pressurizing the fuel supplied from the feed pump 104 to a high pressure. Preferably, it is configured to pump to common rail 106 via road 107.

(2) High pressure passage

 Further, as shown in FIG. 12, it is preferable to provide a one-way valve (not shown) at the outlet of the fuel supply pump 103 or at the common rail 106 and the fuel supply pump 103 described later.

 The reason for this is that such a one-way valve allows only the supply of fuel from the fuel supply pump 103 to the common rail 106. Therefore, even when the pressure in the fuel compression chamber 74 is lower than the pressure in the common rail, the backflow can be effectively prevented, and the pressure in the common rail 106 can be effectively prevented from lowering.

(3) Common rail

 As shown in FIG. 12, a plurality of injectors (injection valves) 110 are connected to the common rail 106, and the fuel stored at a high pressure by the common rail 106 is supplied from each injector 110 to the internal combustion engine ( (Not shown). Although not shown, each of these injectors 110 preferably has its discharge amount controlled through an IDU (IDU: Injector Driving Unit). Such an IDU is an electronic control unit (ECU: Electrical

Controlling Unit) and is driven by this ECU drive signal.

 Further, a pressure detector 117 is connected to a side end of the common rail 106, and it is preferable to send a pressure detection signal obtained by the pressure detector 117 to the ECU. That is, when the ECU receives the pressure detection signal from the pressure detector 117, the ECU controls the electromagnetic control valve (not shown) and controls the drive of the IDU according to the detected pressure. preferable.

(4) Piston booster As shown in Fig. 13, the piston pressure increasing device (pressure piston) includes a cylinder 1555, a mechanical piston 1554, a pressurizing chamber 1558, and a solenoid valve 170 The mechanical piston 1554 includes a pressure receiving portion 152 having a relatively large area, and a pressurizing portion 156 having a relatively small area. It is preferable.

 That is, the mechanical piston 154 housed in the cylinder 155 is moved by being pressed by the fuel having the common rail pressure in the pressure receiving portion 152, and the common rail pressure of the pressurizing chamber 158, for example, The fuel having a pressure of about 3 OMPa is pressurized by the pressurizing section 156 having a relatively small area to a value within the range of 150 MPa to 300 MPa. Is preferred.

 In addition, a large amount of fuel with common rail pressure is used to pressurize the mechanical piston 154, but after pressurization, the fuel is transferred to a fuel tank, etc., via an electromagnetically driven overflow valve 170. It is preferred to reflux. That is, most of the fuel having the common rail pressure is preferably returned to the fuel tank or the like together with the fuel flowing out of the electromagnetic valve 180 of the fuel injection device after pressurizing the mechanical piston 154.

On the other hand, the fuel whose pressure has been increased by the pressurizing section 156 is sent to a fuel injection device (fuel injection nozzle) 163, where it is efficiently injected and burned.

 Therefore, by providing the piston pressure increasing device in this way, the mechanical piston can be effectively pressed by the fuel having the common rail pressure without excessively increasing the size of the common rail.

 That is, as shown in the schematic diagram of FIG. 14, according to the APCRS system, a mechanical piston is provided with a relatively large-area pressure receiving section and a relatively small-area pressurizing section. By considering the stroke of the piston, it is possible to reduce the pressure loss of fuel having a small common rail pressure to a desired value efficiently.

More specifically, the fuel (pressure: p1, volume: V1, work: W1) from the common rail is received by a pressure receiving section having a relatively large area, and a pressurizing section having a relatively small area is received. With the mechanical piston provided, it can produce higher pressure fuel (pressure: _P2 , volume: V2, work: W2). (5) Fuel injection device

 The form of the fuel injection device (fuel injection nozzle) 110 is not particularly limited. For example, as shown in FIG. 13, a seating surface 16 4 on which the needle valve element 16 2 is seated A nozzle pod 163 having a nozzle hole 165 formed downstream of the seating surface 164 of the seating portion 164 from the valve body contact portion, and seating when the needle valve body 162 is lifted. It is preferable that the fuel supplied from the upstream side of the surface 164 be guided to the injection hole 165.

 In such a fuel injection nozzle system 166, the needle valve body 162 is constantly urged toward the seating surface 1664 by a spring 161, etc., and is sent from the upstream side. It is preferable that the nozzle is an automatic opening and closing type nozzle that lifts the needle valve element 162 by the oil pressure of the fuel. Further, such a fuel injection nozzle system 166 is preferably of an electromagnetic valve type that opens and closes the needle valve body 162 by switching between energization / non-energization of a solenoid 180.

 Further, as for the high-pressure fuel injection timing chart, as shown in FIG. 15, it is preferable to show a fuel injection chart having a two-stage injection state as shown by a solid line A.

 The reason is that the two-stage injection timing chart can be achieved by the combination of the common rail pressure and the pressure increase in the piston pressure increase device (pressure increase piston), thereby increasing the fuel combustion efficiency. In addition, it is possible to purify exhaust gas.

 Further, according to the present invention, it is also preferable to show a fuel injection chart as shown by a dotted line B in FIG. 15 by a combination of the common rail pressure and the pressure increase in the piston pressure increasing device (pressure increasing piston).

 In addition, when the piston pressure reducing device (pressure piston) is not used, that is, the conventional injection timing chart is a one-stage injection timing chart of a low injection amount as shown by a dotted line C in FIG.

(6) Operation Next, the operation of the fuel supply pump 103, the piston pressure booster (pressure boosted biston) 108 and the fuel 3 ^ injection device 110 in the present embodiment will be described with reference to FIGS. I will explain it. That is, when the fuel injection device (fuel injection nozzle) 166 operates, the fuel in the fuel tank 102 is transferred from the feed pump 104 to the fuel supply pump 103 as shown in FIG. It is preferable to supply high-pressure fuel from the fuel supply pump 103 to the high-pressure passage 107 under pressure.

 Next, as shown in Fig. 13, the pressure is accumulated at about 50 MPa by the common rail 106, and further, between the fuel injection valve 110 and the piston booster (pressure booster piston) 108 It is preferable to pressurize under ultra-high pressure conditions of, for example, 150 MPa or more.

 In the present embodiment, a very large flow rate of fuel is used to operate the piston pressure intensifier (pressure intensifying piston) 108. Therefore, in the example shown in FIG. The plunger barrel and the pump housing provided in are functioning effectively.

 That is, by providing the projection for supporting the upper end of the return spring on the plunger barrel instead of the pump housing, the inner peripheral surface of the pump housing can be machined precisely and easily. As a result, the rotation speed of the camshaft can be set to be high, so that a sufficiently pressurized large flow rate of fuel can be supplied to the accumulator. Therefore, for example, it is possible to further increase the pressure of APCRS (Amplified Piston Common Rail System), further increase the output of diesel engines, improve fuel efficiency, reduce black smoke, etc. Become. Industrial applicability

According to the fuel supply pump of the present invention, since the upper end of the return spring is supported by the projection of the plunger barrel, the projection for supporting the upper end of the return spring on the inner peripheral surface of the pump housing. Section can be omitted. In addition, the inner peripheral surface of the pump housing can be easily and accurately processed, and the rotational speed of the camshaft can be set higher. With the new technology, it is now possible to supply a large flow rate of fuel, which is sufficiently pressurized compared to the past, to the accumulator, further increase the output of the diesel engine, improve fuel efficiency, reduce black smoke, etc. It is now possible.

Claims

1. A pump housing having a cylindrical space that opens vertically.  A plunger barrel mounted on the upper opening of the pump housing, a plunger disposed in the plunger barrel and the cylindrical space so as to be movable up and down, and pressurizing fuel;  The pump housing is rotatably disposed below the plunger, and the pump housing has A cam integrated with the passed camshaft,  It is disposed between the cam and the plunger, and surrounds the rotational force of the cam shaft. A tap structure for transmitting to the plunger as a lifting force;  A fuel supply pump, which is provided between the tut structure and the plunger barrel and includes a return spring for applying a descending force to the plunger.  A fuel supply pump, wherein the plunger barrel has a protrusion for supporting an upper end of the return spring. 2. The fuel supply pump according to claim 1, wherein the plunger barrel has a large-diameter portion for restricting a radial movement of the return spring. 3. The fuel supply pump according to claim 1, wherein the projection of the plunger barrel has an outer peripheral surface that fits the outer peripheral surface of the cylindrical space of the pump housing. 4. The fuel supply pump according to claim 3, wherein the plunger barrel has a seal ring receiving portion on an outer peripheral surface of the projection. 5. A spring seat having an opening for penetrating the plunger is provided between the return spring and the tappet structure, and an outer peripheral portion of the spring seat is provided below the return springe. 5. The fuel supply pump according to claim 1, further comprising a spring holding portion for restricting movement. 6. The tut structure further includes a cylindrical shell having an outer peripheral surface adapted to a peripheral surface of the cylindrical space of the pump housing, and a radial movement of the return spring is provided on an inner surface of the shell. The fuel supply pump according to any one of claims 1 to 5, further comprising a protrusion for regulating pressure. 7. It is characterized in that it is used for a pressure accumulating type fuel injection device for pressurizing a fuel having a flow rate per unit time of 500 to 1,500 liters to a value of 50 MPa or more. The fuel supply pump according to any one of claims 1 to 6.