JP2001073899A - Drive device of high-pressure fuel pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve miniaturization of a two-cycle engine of cylinder fuel injection type by reducing the number of component items of the fuel supply system and driving a high-pressure fuel pump using a ring-shaped member for joining crank journals. SOLUTION: From an injector 21, fuel is injected into each cylinder of a two-cycle engine, and a high-pressure fuel pump 24 to supply the fuel to the injector 21 is driven directly by a crankshaft 3. The crankshaft 3 is formed by press-fitting a plurality of crank journals into a joining ring 54, and a plunger 25 of the pump 24 is contacted with a cam face 63 formed on the outside surface of the ring 54, and the pump 24 is driven by the ring 54.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving apparatus for a high-pressure fuel pump in a direct injection two-cycle engine.

[0002]

2. Description of the Related Art In a leisure vehicle, a snowmobile, etc., a two-cycle engine is frequently used. Even in a two-cycle engine, there is an in-cylinder fuel injection type engine in which high-pressure fuel is directly injected into a cylinder. Is being developed. In this type of engine, fuel can be atomized to improve combustion by directly injecting high-pressure fuel into the cylinder after the exhaust port is closed, and stratified combustion at low speeds and low loads reduces fuel consumption. Can be improved.

In order to inject high-pressure fuel directly into a cylinder, it is necessary to provide a high-pressure fuel pump in a fuel supply system. In the four-cycle engine, the high-pressure fuel pump is driven by the camshaft of the valve train. However, in the case of the two-cycle engine, no camshaft is provided.
Conventionally, for example, as disclosed in Japanese Patent Application Laid-Open No. 10-246165, the rotation of a crankshaft is transmitted to a high-pressure fuel pump by a belt.

On the other hand, in a two-cycle engine for a multi-cylinder engine, a plurality of crank journals are joined and assembled without making the crankshaft integral, for example, as disclosed in Japanese Patent Application Laid-Open No. 8-74832. An assembled crankshaft of the type described above may be used.

[0005]

As described above, in order to transmit the rotation of the crankshaft to the high-pressure fuel pump by the belt, two pulleys provided on each of the crankshaft and the high-pressure fuel pump, and the pulleys mounted on the two pulleys. It is necessary to use the delivered belt, and not only the number of parts constituting the engine increases, but also a space for installing them must be secured.

On the other hand, in an engine using an assembling crankshaft, a plurality of crank journals are joined by press-fitting into a ring-shaped member, that is, a joining ring, and it is necessary to secure a space for the joining ring. is there.

An object of the present invention is to reduce the number of parts of a fuel supply system in a two-stroke engine of a direct fuel injection type.

Another object of the present invention is to drive the high-pressure fuel pump by means of a joining ring joining the crank journals, thereby utilizing the space of the joining ring to achieve a downsized engine.

[0009]

A drive device for a high-pressure fuel pump according to the present invention is a drive device for a high-pressure fuel pump for injecting high-pressure fuel into a cylinder of a two-cycle engine. A cam surface with which a portion contacts is formed on a crankshaft, and the high-pressure fuel pump is directly driven by the crankshaft.

In the driving device for a high-pressure fuel pump according to the present invention, the crankshaft is formed by press-fitting a plurality of crank journals into a joining ring, and the cam surface is formed on an outer peripheral surface of the joining ring. It is characterized by.

In the present invention, since the high-pressure fuel pump is driven directly by the crankshaft, the number of parts of the fuel supply system can be reduced. In addition, the high pressure fuel pump is driven by the joining ring by bringing the operating portion of the high pressure fuel tank into contact with a cam surface formed on the outer peripheral surface of the joining ring for joining the crank journal by using the crankshaft as an assembling type. Therefore, the pump can be driven by utilizing the installation space of the joining ring, and the size of the engine can be reduced.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic view showing a two-stroke engine provided with a driving device for a high-pressure fuel pump according to an embodiment of the present invention. FIG. 2 is a sectional view showing the engine body shown in FIG. FIG. 3 is a left side view of FIG.

The engine 1 is a three-cylinder two-cycle engine of an in-cylinder fuel injection type. A crankshaft 3 is rotatably mounted in a crankcase 2 composed of a lower case 2a and an upper case 2b. 2
A cylinder 4 is attached to the cylinder 4, and a cylinder head 5 is attached to the cylinder 4.

A piston 7 is reciprocally mounted in a cylinder bore 6 formed in the cylinder 4, and the piston 7 is connected to the crankshaft 3 by a connecting rod 8. An intake port 10 is formed in the crankcase 2 so as to communicate with a crank chamber 9 therein.
A fresh air is introduced into the closed crank chamber 9 through an intake pipe 11. The intake pipe 11 is provided with a throttle valve 12 for adjusting the amount of air to be introduced, and the intake port 10 is provided with a reed valve 13 for preventing backflow.

The cylinder 4 is provided with a scavenging port 14 for communicating the combustion chamber with the crank chamber 9 and an exhaust port 15 for discharging exhaust gas from the combustion chamber. With the ports 14 and 15 both open, fresh air is filled in the combustion chamber while discharging or scavenging the combustion gas.

As shown in FIG. 2, the cylinder 4 is provided with an exhaust valve 16 for adjusting the timing of exhaust from the exhaust port 15. The valve body 18 changes the exhaust timing according to the balance with the force. When the engine is running at a high speed, the valve body 18 moves backward to perform the exhaust at an early timing, and when the engine is running at a low speed, the valve body 18 moves forward and is slow. Exhaust is performed at the timing.

As shown in FIG. 1, a flywheel magneto 19, which has a function as a magnet generator while smoothing the rotation of the engine, is directly connected to the crankshaft 3.

The cylinder head 5 is provided with a fuel injection valve, that is, an injector 21 and a spark plug 22. As shown in FIG. 1, the fuel in the fuel tank 23 is supplied to the injector 21 by a fuel supply system. Has become.
The fuel supply system has a high-pressure fuel pump 24 attached to the crankcase 2, and an operating part of the high-pressure fuel pump 24, that is, a plunger 25 is directly driven by the crankshaft 3.

As shown in FIG. 3, a common pipe, that is, a branch portion of a common rail 26 is connected to the injector 21 so that the fuel pressurized by the high-pressure fuel pump 24 is branched and supplied from the common rail 26. ing.
The discharge port 27 of the high-pressure fuel pump 24 is provided upward,
The discharge port 2 is connected to a high pressure pipe 28 connected to the discharge port 27.
7 is connected to a common rail 26. High pressure pipe 28
3 extends straight upward without deformation in the axial direction of the crankshaft 3 as shown in FIG. 3 and inclines in the width direction of the engine toward directly above the crankshaft 3 as shown in FIG. are doing.

As described above, the discharge port 27 of the high-pressure fuel pump 24 directly driven by the crankshaft 3 is formed upward, and the high-pressure pipe 28 extends upward toward the injector 21 provided in the cylinder head 5. Since there is no portion meandering upward from the horizontal direction or downward, the length of the high-pressure pipe 28 between the discharge port 27 and the injector 21 can be shortened. High-pressure fuel can be supplied to the injector 21 while suppressing generation of pulsation. Further, since the discharge port 27 is directed upward and the high-pressure pipe 28 is further extended upward to shorten the high-pressure pipe 28, even if engine vibration is transmitted to the high-pressure pipe 28,
Can be improved in durability. Further, the discharge port 2
Since the 7 is upward, even if bubbles are generated in the discharge port 27, it is possible to prevent the bubbles from staying in the discharge port 27.

A low-pressure pipe 32 connected between the inlet 31 of the high-pressure fuel pump 24 and the fuel tank 23 has a water separator or filter 33 and a low-pressure fuel pump 34.
The return pipe 36 connected between the return port 35 of the high-pressure fuel pump 24 and the fuel tank 23 is connected to the discharge side of the low-pressure fuel pump 34 by a pressure adjusting pipe 37. A low-pressure pressure regulator 38 for adjusting the fuel pressure discharged from the low-pressure fuel pump 34 is provided. The fuel in the fuel tank 23 is reduced by the low-pressure fuel pump 34 to, for example, 3 kgf / cm ²
After being pressurized to about the pressure, the pressure is increased to, for example, about 70 kgf / cm ² by the high-pressure fuel pump 24 and supplied to the injector 21.

The ignition plug 22 is driven by an igniter 39, and the injector 21 is connected to an injector driver 40.
Igniter 39,
Injector driver 40 and low pressure fuel pump 34
The operation is controlled by a control signal from the electronic control unit ECU.

The electronic control unit ECU includes an atmospheric pressure sensor 41, a fuel pressure sensor 42, a crank angle sensor 4
3, crankcase temperature sensor 44, intake air temperature sensor 4
5. Signals from the throttle valve opening sensor 46 and the water temperature sensor 47 are sent. The water temperature sensor 47 detects the temperature of the coolant flowing through the water jacket formed in the cylinder head 5 and the cylinder 4, and the circulation supply port 48 for supplying the coolant into the water jacket is provided in FIG. 2 and FIG. As shown in FIG. 3, it is formed on the cylinder head 5.

FIG. 4 is a sectional view showing the crankshaft 3.
It is formed by assembling three crank journals 1a, a second crank journal 51b, and a third crank journal 51c. Each of the crank journals 51a to 51c has a counterweight, that is, a balance weight 53 connected by a crankpin 52, and the connecting rod 8 is coupled to the crankpin 52.

In order to join the first crank journal 51a and the second crank journal 51b, a joining ring 54 is press-fitted into these ends to join the second crank journal 51b and the third crank journal 51c. A joining ring 55 is press-fitted into these ends. By pressing the ends of the crank journals into the respective joining rings 54 and 55, one crankshaft 3 is assembled by the three crank journals 51a to 51c.

In order to discharge the air in the joining rings 54 and 55 to the outside at the time of press-fitting, the joining ring 54 is formed with a radial discharge hole 56 for communicating the inner peripheral surface and the outer peripheral surface. Are formed with a radial discharge hole 57 and an axial discharge hole 58 communicating therewith. When the press-fitting is completed, the end faces of the respective crank journals are in a state of being abutted.

FIG. 5A is a perspective view showing the joining ring 54, and FIG. 5B is a front view showing the joining ring 54. The joining ring 54 constitutes a cam member, and the main body 61 having the rotation center O _C of the crankshaft 3 as an axis.
And an outer peripheral surface of the cam portion 62, that is, a cam surface 63.
Axis O _E is shifted by the rotation center O _C eccentricity E, the radius from the rotation center O _C of the crankshaft 3 in a small point 63a in the direction of rotation 180 degree phase large径点63b of Are shifted by the cam lift L. This cam surface 63
The plunger 25 of the high-pressure fuel pump 24 is in contact with the plunger 25, and the plunger 25 is rotated by one rotation of the crankshaft 3 with a stroke of the cam lift L determined by the eccentricity E.
Reciprocating times. The stroke of the plunger 25 can be changed to an arbitrary value by changing the amount of eccentricity E.

As described above, the crank journals 51a,
By driving the high-pressure fuel pump 24 using the joining ring 54 for joining the 51b, the high-pressure fuel pump 24 can be directly driven by the crankshaft 3 and effectively use the space of the joining ring 54. A driving space can be secured. Moreover, the joining ring 54 is provided between the cylinder on the left side and the cylinder at the center in FIG. 3, and the high-pressure fuel pump 24 is disposed at that portion. The high-pressure fuel pump can be arranged using the space between the cylinders without increasing the size.

FIG. 6 is a view showing a modification of the joining ring 54. The joining ring 54 has a small diameter point 63a and a large diameter point 6a.
3b are provided two at a time, and each is shifted by 90 degrees, so that the plunger 25 reciprocates twice each time the crankshaft 3 makes one rotation.

A gear 64 for driving an oil pump (not shown) is attached to the joining ring 55.
Lubricating oil is supplied to the sliding portion by an oil pump driven by the gear 64.

The sliding surface in the crankcase 2 and the piston 7
In order to lubricate the sliding surface, lubricating oil is dripped into fresh air flowing through the intake pipe 11, and the dripped and atomized lubricating oil enters the crank chamber 9 together with the fresh air. Will be flowed in. A lubricating oil introduction hole 66 is formed in the crankcase 2 to supply the inflowing lubricating oil to a plurality of bearings 65 that rotatably support the crankshaft 3.

In order to lubricate the sliding surface between the cam surface 63 and the plunger 25, as shown in FIG. 2, a lubricating oil passage 67 for guiding lubricating oil from an oil pump 2 are connected. In the crankcase 2, an oil reservoir chamber for storing the lubricating oil discharged from the oil pump, that is, an oil bath 68 is formed adjacent to the opening of the lubricating oil passage 67. The oil bath 68 is formed of a bottom surface of the crankcase 2 or a ring-shaped member incorporated in the crankcase 2, and the lubricating oil stored therein is used for the cam surface 6.
3, the lubricating oil attached to the cam surface 63 with the rotation of the crankshaft 3 is supplied between the plunger 25 and the cam surface 63, and the contact surface is forcibly lubricated.

By reducing the gap between the outer peripheral surface of the main body 61 of the joining ring 54 and the inner peripheral surface of the crankcase 2 opposed thereto, the oil bath 68 becomes a closed space in which the oil bath 68 is stored. The leaked lubricating oil is suppressed or blocked from leaking from both sides of the cam portion 62 so that a predetermined amount of lubricating oil is accumulated in the oil bath 68. However, the bearings 65 on both sides of the joining ring 54 may be lubricated by leaking the lubricating oil.

FIG. 7 is a sectional view showing a modification of the joining ring 54. In this case, the main body 61 and the cam 62 are separate members, and the cam 62 is pressed into the outside of the main body 61. By doing so, the joining ring 54 is formed.
The joining ring 54 is provided with a labyrinth 69 including a plurality of annular concave portions and an annular protrusion on the outer peripheral surface of the main body 61, so that leakage of lubricating oil from the oil bath 68 is suppressed by the labyrinth 69. I have to. In addition,
The labyrinth 69 may be provided on the crankcase 2 side, or may be provided on both the main body 61 and the crankcase 2. When the cam portion 62 is press-fitted to the outside of the main body portion 61, it is preferable to form a radial discharge hole 57 and an axial discharge hole 58 in the same manner as the joining ring 55.

The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

For example, in the embodiment, the present invention is applied to a three-cylinder engine, but the number of cylinders is not limited to this, and the present invention may be applied to an engine having an arbitrary number of cylinders. Can be.

[0038]

As described above, in the present invention, the high-pressure fuel pump for supplying high-pressure fuel to the injector for injecting fuel into the cylinder is directly driven by the crankshaft, so that the number of parts is increased. Therefore, the high-pressure fuel pump can be driven without any need. A crankshaft is formed by press-fitting a plurality of crank journals into the joining ring, and a cam surface is provided on the outer peripheral surface of the joining ring to contact the operating portion of the high-pressure fuel pump. The pump can be driven, and the installation space can be effectively used to achieve downsizing of the engine.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a two-stroke engine provided with a driving device for a high-pressure fuel pump according to an embodiment of the present invention.

FIG. 2 is a sectional view showing the engine main body shown in FIG.

FIG. 3 is a left side view of FIG. 2;

FIG. 4 is a sectional view showing a crankshaft.

FIG. 5A is a perspective view showing a joining ring;
(B) is a front view which shows a joining ring.

FIG. 6 is a front view showing a modification of the joining ring.

FIG. 7 is a sectional view showing a modification of the joining ring.

[Explanation of symbols]

 2 Crank Case 3 Crank Shaft 4 Cylinder 5 Cylinder Head 9 Crank Chamber 10 Intake Ports 51a to 51c Crank Journal 21 Injector 24 High-Pressure Fuel Pump 25 Plunger 54 Joining Ring 62 Cam Part 63 Cam Surface

Claims (2)

[Claims] 1. A high-pressure fuel pump drive device for injecting high-pressure fuel into a cylinder of a two-cycle engine, wherein a cam surface with which an operating part of the high-pressure fuel pump contacts is formed on a crankshaft, The high-pressure fuel pump drive device according to claim 1, wherein the high-pressure fuel pump is directly driven. 2. The driving device for a high-pressure fuel pump according to claim 1, wherein the crankshaft is formed by press-fitting a plurality of crank journals into a joining ring,
A driving device for a high-pressure fuel pump, wherein the cam surface is formed on an outer peripheral surface of the joining ring.