JP2000265916A - Fuel pump structure of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To downsize an engine. SOLUTION: A valve system 19 is arranged for opening and closing intake and exhaust valves by means of a plurality of rocker arms 26, 27 supported by a plurality of rocker shafts 30, 31 due to rotation of intake and exhaust cams 24, 25 arranged on a camshaft 21. A fuel pump 36 is operated by reciprocation of a plunger 38. In an engine having such a setup, an eccentric cam 39 is arranged on the camshaft 21 for driving the fuel pump 36. A pump rod 40 is arranged for transmitting the rotation of the eccentric cam 39 to the plunger 38. A rod holder 41 is arranged on rocker shafts 30, 31 for supporting the pump rod 40 at a specified position. The rocker arms 26, 27 can be positioned by the rod holder 41.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fuel pump structure for an engine.

[0002]

2. Description of the Related Art For example, an engine mounted on an outboard motor includes an engine equipped with a mechanical fuel pump that operates by the reciprocating motion of a plunger. The plunger is usually driven by an eccentric cam provided on a camshaft that normally constitutes a valve train of the engine. In this case, the fuel pump is mounted on a cylinder head cover that covers the valve train provided in the cylinder head. It is provided in.

[0003]

However, the eccentric cam for driving the fuel pump needs to be provided at the end of the camshaft so as not to hinder the operation of the valve operating cam. This leads to an increase in size of the engine.

[0004] For the same reason, it is also difficult to provide a plurality of fuel pumps on the cylinder head cover.

The present invention has been made in consideration of the above circumstances, and has as its object to provide a fuel pump structure for an engine in which the size of the engine is reduced.

It is another object of the present invention to provide a fuel pump structure for an engine, in which a plurality of fuel pumps can be installed.

[0007]

According to a first aspect of the present invention, there is provided a fuel pump structure for an engine, comprising: an intake / exhaust cam provided on a camshaft; A plurality of rocker arms supported on a plurality of rocker shafts by rotation are provided with a valve operating device for opening and closing an intake / exhaust valve, and an engine equipped with a fuel pump operated by a reciprocating motion of a plunger. An eccentric cam for driving the fuel pump is provided, a pump rod for transmitting the rotation of the eccentric cam to the plunger is provided, and a rod holder for supporting the pump rod at a predetermined position is provided on the rocker shaft. The rocker arm can be positioned by a holder.

According to another aspect of the present invention, the rod holder includes a plurality of legs, one of which is disposed on one of the rocker shafts. While holding the rocker arm from both sides,
The other leg is provided between the two rocker shafts so as to be sandwiched between a plurality of rocker arms arranged on the other rocker shaft.

Further, in order to solve the above-mentioned problems,
As described in claim 3, the rod holder has at least two legs, these legs are bridged between different rocker shafts, and the rod holder has a support hole for supporting the pump rod. It is formed.

Further, in order to solve the above-mentioned problem, as set forth in claim 4, the rod holder is formed in a substantially T-shape having three legs, and two legs are connected to one side. And the other one is supported by the other rocker shaft.

Then, in order to solve the above-mentioned problem,
As described in claim 5, a plurality of the fuel pumps are provided.

[0012]

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

FIG. 1 is a left side view of an outboard motor to which the present invention is applied. As shown in FIG. 1, the outboard motor 1 includes an engine holder 2, and an engine 3 is installed above the engine holder 2. An oil pan 4 is arranged below the engine holder 2 and the
The outboard motor 1 is mounted on the transom 6a of the hull 6 via the bracket 5.
Although not shown, for example, there is a small outboard motor or the like in which an engine is installed above an oil pan without an engine holder, and in this case, a bracket is attached to the oil pan.

The engine 3 mounted on the outboard motor 1 includes:
For example, it is a water-cooled four-cycle four-cylinder engine configured by combining a cylinder head cover 7, a cylinder head 8, a cylinder block 9, a crankcase 10, and the like, and the periphery of the engine 3 is covered by an outboard motor cover 11.

A cylinder block 9 is disposed at the forefront of the engine 3, that is, behind (right side) a crankcase 10 disposed on the left side in FIG. A cylinder head 8 is disposed behind the cylinder block 9. The crankshaft 12 is disposed substantially vertically in the joint between the crankcase 10 and the cylinder block 9.
Further, the rear opening of the cylinder head 8 is covered by the cylinder head cover 7.

A shaft housing 13 is provided below the engine 3. A drive shaft 14 is disposed substantially vertically in the shaft housing 13, and an upper end thereof is connected to a lower end of the crankshaft 12. The drive shaft 14 extends downward in the shaft housing 13 and is configured to drive a propeller 18 via a bevel gear 16 and a propeller shaft 17 in a gear case 15 provided at a lower portion of the shaft housing 13.

FIG. 2 is a longitudinal sectional view of the engine 3, showing a first embodiment of the present invention. 3 is an enlarged vertical sectional view of the cylinder head 8 of the engine 3 shown in FIG. 2, and FIG. 4 is a view taken in the direction of the arrow IV in FIG. 3, and shows the rear surface of the cylinder head 8 with the cylinder head cover 7 removed. FIG. FIG. 5 is a sectional view taken along the line VV in FIG.

As shown in FIG. 2 to FIG.
A valve gear 19 is provided in the cylinder head 8.
The valve gear 19 is disposed in parallel with the crankshaft 12, and is connected to the crankshaft 1 via a timing belt 20.
The rotation of the camshaft 21 to which the rotation of the camshaft 2 is transmitted, the intake valve 22 and the exhaust valve 23, and the rotation of the intake / exhaust cams 24 and 25 for the valve operating provided on the camshaft 21 are transmitted to the two valves 22 and 23. The intake and exhaust rocker arms 26 and 27 are supported by bearings 28 and 29, and the intake and exhaust rocker shafts 30 and 31 that support the rocker arms 26 and 27 are provided as main components.

The valve gear 19 of the engine 3 shown in this embodiment has two intake valves 22 and two exhaust valves 23 for each cylinder, and these two valves 22 and 23 are provided on the camshaft 21. Each cylinder is provided with two cam rows 24 and 25 of intake cams 24 and exhaust cams 25. Further, these cam rows 24, 25 are set, for example, in an array in which exhaust cams 25 are arranged on both sides of two intake cams 24, respectively.

Supporting portions 26a, 27a of both rocker arms 26, 27 are rotatably supported on both rocker shafts 30, 31, and the tip portions 26 of both rocker arms 26, 27 are supported.
b, 27b are in contact with the tops of the valves 22, 23.
The rotation of the camshaft 21 causes the rocker arm 2 to rotate.
The cam floor surfaces 26c, 27c of 6, 27 are pushed up by the intake / exhaust cams 24, 25 to open and close the valves 22, 23. The valves 22 and 23 are held in a normally closed state by a valve spring 32.

A shaft spacer 33 is disposed between the bearing 28 of the intake rocker shaft 30 and the support 26a of the intake rocker arm 26 so that the intake rocker arm 26 is positioned on the intake rocker shaft 30. And the two bearing portions 29 of the exhaust rocker shaft 31.
A shaft spring 34 is disposed between the support portions 27a of the two exhaust rocker arms 27 disposed therebetween, and the exhaust rocker arm 27 is positioned on the exhaust rocker shaft 31.

The engine 3 of the outboard motor 1 includes a fuel supply device 35. The fuel supply device 35 includes a mechanical fuel pump 36 and a driving mechanism 37 for the fuel pump 36. The fuel pump 36 pumps and pumps fuel by the forward and backward movements of a plunger 38 whose tip projects outward. For example, the fuel pump 36 is disposed on the cylinder head cover 7. The drive mechanism 37 of the fuel pump 36 is provided on the valve operating device 19.

One of the cam rows 24, 25 of the valve train 19 provided for each cylinder, in the present embodiment, the center of the cam rows 24, 25 of the cylinder arranged at the bottom, ie, two An eccentric cam 39 constituting a drive mechanism 37 of the fuel pump 36 is provided on the camshaft 21 between the intake cams 24. The fuel pump 36 is disposed substantially horizontally on the side of the eccentric cam 39 for driving the fuel pump 36 so that the reciprocating line of the plunger 38 is orthogonal to the axis of the camshaft 21. A pump rod 40 is provided between the pump rod 40 and the plunger 38, and the rotation of the eccentric cam 39 causes the plunger 38 to move forward and backward through the pump rod 40.

In the vicinity of the cam rows 24 and 25 provided with the eccentric cams 39 for driving the fuel pump 36, a rod holder 41 for supporting the pump rod 40 at a predetermined position is disposed.
The rod holder 41 is formed in a substantially T shape having a plurality of, in this embodiment, three legs 42a, 42b, and 42c, and is bridged between the intake rocker shaft 30 and the exhaust rocker shaft 31. You.

A support hole 43 for supporting the pump rod 40 is formed substantially in the center of the rod holder 41. The rod holder 41 has two legs 42a and 42b extending around the support hole 43 on the side of the intake rocker shaft 30 and one leg 42c on the side of the exhaust rocker shaft 31. It is extended. Further, the intake rocker shaft 30 is inserted into the free ends of the intake rocker shaft 30 side legs 42a and 42b, and the exhaust rocker shaft 31 is inserted into the free end of the exhaust rocker shaft 31 side legs 42c. The rod holder 41 is fixed at a predetermined position.

The free ends of the legs 42a, 42b on the side of the intake rocker shaft 30 are connected to the shaft spacer 33.
Bearing 28 of the intake rocker shaft 30
And the support portion 26 a of the intake rocker arm 26, and positions the intake rocker arm 26 on the intake rocker shaft 30. The free end of the exhaust rocker shaft 31 side leg 42c is sandwiched between the support portions 27a of the two exhaust rocker arms 27 with the function of the shaft spring 34, and the exhaust rocker arm 27 is connected to the exhaust rocker shaft 31. Position above.

FIG. 6 shows a second embodiment of the present invention, in which the same components as those in the first embodiment are denoted by the same reference numerals.

In the second embodiment, a plurality of fuel supply devices 35 for the engine 3 of the outboard motor 1 are provided, and in the present embodiment, two mechanical fuel pumps 36 and two fuel pumps 3 are provided.
6 drive mechanism 37. The fuel pumps 36 are vertically arranged on the cylinder head cover 7 and two of the cam rows 24 and 25 of the valve train 19 provided for each cylinder. An eccentric cam 39 for driving the fuel pump 36 is provided at the center of each of the cam rows 24, 25 of the cylinders arranged above, that is, between each two intake cams 24.

Since both fuel pump drive mechanisms 37 have the same structure as the drive mechanism 37 of the above-described first embodiment, the components and functions thereof are omitted. In addition,
The number of fuel pumps 36 can be increased as necessary, up to the number of cylinders of the engine 3 and up to four in this embodiment.

Next, the operation of the present embodiment will be described.

A rod holder 41 for supporting a pump rod 40 for driving the fuel pump 36 is provided between the intake rocker shaft 30 and the exhaust rocker shaft 31, so that the cam rows 24 and 25 of the valve train 19 are formed. An eccentric cam 39 for driving the fuel pump 36 can be provided at the center. As a result, the fuel pump 3 is positioned on the cylinder axis of each cylinder.
6, it is not necessary to provide the eccentric cam 39 for driving the fuel pump 36 at the end of the camshaft 21 unlike the conventional case, and the camshaft 21 can be shortened, which leads to downsizing of the engine 3. .

Further, since a dedicated space for the fuel pump driving mechanism 37 is not required, as shown in the second embodiment, even if a plurality of fuel pumps 36 are provided, there is no space limitation. The fuel supply efficiency is improved by providing the plurality of fuel pumps 36.

Further, the rod holder 41 has a plurality of, in this embodiment, three legs 42a, 42b, 42c.
The free ends of the leg portions 42a and 42b on the side of the intake rocker shaft 30 in this embodiment are connected to the bearing portion 28 of the intake rocker shaft 30 and the support portion 26a of the intake rocker arm 26. The function of the shaft spacer 33 is provided by being sandwiched therebetween, and the other leg, in this embodiment, the leg portion 4 on the side of the exhaust rocker shaft 31.
By providing the function of the shaft spring 34 by holding the free end of 2c between the two support portions 27a of the exhaust rocker arm 27, the positioning of the intake rocker arm 26 and the exhaust rocker arm 27 can be facilitated. At this time, each leg 42a, 42 of the rod holder 41
Since b and 42c have the functions of the shaft spacer 33 and the shaft spring 34, the number of parts can be reduced.

[0034]

As described above, according to the fuel pump structure of the engine according to the present invention, the plurality of rocker arms supported on the plurality of rocker shafts by the rotation of the intake / exhaust cam provided on the camshaft. In an engine having a valve operating device for opening and closing the intake / exhaust valve and a fuel pump operated by a reciprocating motion of a plunger, an eccentric cam for driving the fuel pump is provided on the camshaft. A pump rod for transmitting rotation to the plunger is provided, and a rod holder for supporting the pump rod at a predetermined position is provided on the rocker shaft, while the rocker arm can be positioned by the rod holder. Can be shortened, the engine size can be reduced, and the number of parts can be reduced. That.

The rod holder has a plurality of legs, one of the legs holds a rocker arm disposed on one of the rocker shafts from both sides, and the other leg has the other of the rocker shafts. Since the two rocker shafts are sandwiched between the plurality of rocker arms arranged above, the camshaft can be shortened, the size of the engine can be reduced, and the positioning of the rocker arms becomes easy.

Further, the rod holder has at least two legs, and these legs are bridged between different rocker shafts, and the rod holder has a support hole for supporting the pump rod. And the positioning of the pump rod is facilitated.

Further, the rod holder is formed in a substantially T-shape having three legs, and the two legs are supported by one rocker shaft, and the other is supported by the other rocker shaft. Since the configuration is made to support, the size of the engine can be reduced and the rocker arm can be easily positioned.

Since a plurality of the fuel pumps are provided, the fuel supply efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a left side view of an outboard motor showing an embodiment of an engine fuel pump structure according to the present invention.

FIG. 2 is a longitudinal sectional view of the engine showing the first embodiment of the present invention.

FIG. 3 is an enlarged vertical sectional view of a cylinder head showing the first embodiment of the present invention.

FIG. 4 is a view taken in the direction of the arrow IV in FIG. 3;

FIG. 5 is a sectional view taken along the line VV in FIG. 3;

FIG. 6 is an enlarged vertical sectional view of a cylinder head showing a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outboard motor 3 Engine 7 Cylinder head cover 8 Cylinder head 9 Cylinder block 19 Valve train 21 Camshaft 22 Intake valve 23 Exhaust valve 24 Intake cam 25 Exhaust cam 26 Intake rocker arm 27 Exhaust rocker arm 30 Intake rocker shaft 31 Exhaust Rocker shaft 35 Fuel supply device 36 Fuel pump 37 Fuel pump drive mechanism 38 Plunger 39 Eccentric cam for driving fuel pump 40 Pump rod 41 Rod holder 42a, 42b, 42c Rod holder leg 43 Support hole for pump rod support

Claims (5)

[Claims] A plurality of rocker arms supported by a plurality of rocker shafts are provided with valve operating devices for opening and closing intake / exhaust valves by rotation of intake / exhaust cams provided on a camshaft, and forward / backward movement of a plunger. Eccentric cam 39 for driving the fuel pump 36 on the camshaft 21
And the rotation of the eccentric cam 39 is controlled by the plunger 38.
And a rod holder 41 for supporting the pump rod 40 at a predetermined position.
The fuel pump structure of the engine, wherein the rocker arms 26 and 27 are positioned by the rod holder 41 while the rockers are provided on the rocker shafts 30 and 31. 2. The rod holder 41 includes a plurality of legs 4
2a, 42b, 42c, and one of the legs 42a, 42
b clamps the rocker arm 26 disposed on one rocker shaft 30 from both sides, and the other leg 4
2. The engine fuel pump structure according to claim 1, wherein 2c is provided between the two rocker shafts 30 and 31 so as to be sandwiched between a plurality of rocker arms 27 disposed on the other rocker shaft 31. 3. 3. The rod holder 41 has at least two legs 42a, 42b, 42c.
Rocker shafts 30, 3 having different 2a, 42b, 42c
3. The engine fuel pump structure according to claim 2, wherein said rod holder is provided with a support hole for supporting said pump rod. 4. The rod holder 41 has three legs 42.
a, 42b, and 42c so that the two legs 42a and 42b are supported by one rocker shaft 30 and the other one 42c is supported by the other rocker shaft 31. The fuel pump structure for an engine according to claim 2, wherein 5. The engine fuel pump structure according to claim 1, further comprising a plurality of said fuel pumps.