JP3887210B2 - Engine valve gear - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a valve operating apparatus for an engine, and in particular, an axis is substantially the same as the plane on one side of a plane including both axes of the first valve and the second valve corresponding to one and the other of an intake valve and an exhaust valve. A first rocker arm having an orthogonal camshaft and swingably supported by a rocker shaft disposed between the camshaft and the first valve and the second valve substantially perpendicular to the plane. Further, the present invention relates to an improvement in a structure in which the first and second valves are connected to each other via a second rocker arm and the first and second valves are driven to open and close by rotation of a cam shaft.
[0002]
[Prior art]
Such a valve gear is already known as disclosed in Japanese Patent Laid-Open No. 8-74524.
[0003]
[Problems to be solved by the invention]
In the apparatus disclosed in the above publication, the first and second rocker arms are supported by independent first and second rocker shafts, respectively, so that the number of parts is large and it is difficult to reduce the cost.
[0004]
The present invention has been made in view of such circumstances, and the first and second rocker arms can be firmly supported by a common single rocker shaft so that the number of parts can be reduced and the structure can be made compact. An object of the present invention is to provide a valve operating device for the engine.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an axis substantially perpendicular to the plane on one side of a plane including both axes of the first valve and the second valve corresponding to one and the other of the intake valve and the exhaust valve. A first rocker arm that is swingably supported by a rocker shaft that is disposed substantially perpendicular to the plane between the cam shaft and the first valve and the second valve. In the valve operating apparatus of the engine, which is connected via the second rocker arm and is driven to open and close by rotation of the camshaft, an intake cam and an exhaust cam are adjacent to the camshaft. In addition, one of the intake cam and the exhaust cam is formed so that the entire cam is within the base circle of the other cam, and the first rocker arm is connected to the base end of the U-shaped cross section. The opposite side walls are supported by the rocker shaft and the tip is the head of the first valve A first arm abutting, a second arm tip portion protrudes toward the axial direction in sliding contact with the one of the cam surfaces of the intake cam and exhaust cam of a camshaft of the camshaft from the side wall of the first arm Further, the second rocker arm is supported by the same rocker shaft on opposite side walls of the base end portion having a U-shaped cross section inside the first arm of the first rocker arm, and the distal end portion is the second valve. A first arm that abuts the head of the cam shaft, a second arm that protrudes in the axial direction of the cam shaft from one side wall of the first arm, and a tip portion that is in sliding contact with the other cam surface of the intake cam and exhaust cam of the cam shaft It is characterized by comprising an arm.
[0006]
According to this feature, by sharing the rocker shaft with respect to the first and second rocker arms, the number of parts can be reduced, and the assemblability can be improved and the cost can be reduced. In addition, by supporting the both side walls of the base end portions of the first and second rocker arms having a U-shaped cross section on the rocker shaft, the support rigidity of the base end portions is increased, and stable rocking of each rocker arm is guaranteed. In addition, by overlapping the base end portions inside and outside, both the rocker arms can be arranged in a compact manner, and the valve operating device can be made compact.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described below based on embodiments of the present invention shown in the accompanying drawings.
[0008]
FIG. 1 is a longitudinal side view of a main part of a general-purpose engine equipped with a valve operating device of the present invention, FIG. 2 is a view taken in the direction of arrow 2 in FIG. 1, FIG. 3 is a view taken in the direction of arrow 3 in FIG. 4 is a sectional view taken along the line 5-5 in FIG. 1, FIG. 6 is a sectional view taken along the line 6-6 in FIG. 2, FIG. 7 is a sectional view taken along the arrow 7 in FIG. 9 is a sectional view taken along line 9-9 of FIG. 6, FIG. 10 is a longitudinal sectional view (A), left side view (B), right side view (C), and FIG. It is a vertical plane view which shows the modification of this invention engine.
[0009]
First, the overall configuration of the engine will be described.
[0010]
1, 4 and 5, an engine body 1 of the engine E with a balancer includes a crankcase 2, a cylinder block 3 projecting obliquely upward from one side of the crankcase 2, and the cylinder block 3 and a cylinder head 4 joined to the head. The crankcase 2 is installed on the engine bed of various work devices on the installation surface 5 on the lower surface thereof.
[0011]
The crankcase 2 is composed of a case body 1a cast integrally with the cylinder block 3 and having one end face opened, and a side cover 2b coupled to the open end, and the crankshaft is connected to the case body 1a and the side cover 2b. Both ends of 6 are rotatably supported via ball bearings 7, 7 'and oil seals 8, 8'. The crankshaft 6 has an output shaft portion 6o at one end and an auxiliary attachment shaft portion 6a at the other end that protrudes from the crankcase 2, and the flywheel 10 is key-coupled to the auxiliary attachment shaft portion 6a. At the same time, the cooling fan 12 that supplies cooling air to each part of the engine body 1 and a carburetor 30 to be described later is fixed to the outer end surface of the flywheel 10 with a bolt 13. A recoil-type engine starter 14 is disposed outside the cooling fan 12.
[0012]
A stator 15a of a generator 15 is attached to the outer end surface of the crankcase 2 facing the flywheel 10, and the flywheel 10 includes a plurality of magnets 15b arranged on the outer periphery of the stator 15a, and generates power. Also serves as a roller for the machine 15.
[0013]
The crankshaft 6 includes a pair of crankpins 6p and 6p having a phase difference of 360 ° in the crankcase 2. A pair of pistons 17 and 17 are connected to the crank pins 6p and 6p via connecting rods 16 and 16, and a pair of cylinders 18 and 18 into which the pistons 17 and 17 are slidably fitted are parallel to the cylinder block 3. Formed.
[0014]
In the cylinder head 4, combustion chambers 20, 20, intake ports 21, 21 and exhaust ports 22, 22 are formed corresponding to the cylinders 18, 18, and intake ports 21, 21 and exhaust ports 22, 22 are opened and closed. Intake valves 23 and 23 and exhaust valves 24 and 24 are mounted. At that time, the intake ports 21 and 21 and the exhaust ports 22 and 22 are arranged vertically, the upstream ends of the intake ports 21 and 21 open on the upper surface of the cylinder head 4, and the downstream ends of the exhaust ports 22 and 22 are the cylinder heads. 4 opens on the lower surface.
[0015]
The spark plugs 25, 25 that cause the electrodes to face the combustion chambers 20, 20 are screwed to the cylinder head 4 from both the left and right sides.
[0016]
As shown in FIGS. 1, 2, 6 and 7, an intake manifold 27 is fixed to the upper surface of the cylinder head 4 with bolts 28. The intake manifold 27 includes a pair of intake passages 29, 29 that individually communicate with the intake ports 21, 21 and extend horizontally, and the upstream ends of the intake passages 29, 29 are arranged on the cooling side of the cylinder head 4. It opens toward one side on the same side as the fan 12, and a double carburetor 30 is connected to these openings. Thus, the vaporizer 30 is disposed adjacent to the cooling fan 12 in the radial direction.
[0017]
An air cleaner 32 is connected to the upstream end of the carburetor 30 via an intake duct 31 with the upstream end facing upward. The air cleaner 32 is disposed above the cylinder block 3 and the cylinder head 4.
[0018]
The carburetor 30 and the intake duct 31 are coupled to the intake manifold 27 by a plurality of through bolts 33. The air cleaner 32 is attached to the intake duct 31 with a single mounting bolt 34 planted in the intake duct 31.
[0019]
An exhaust manifold 35 is fixed to the lower surface of the cylinder head 4 with bolts 39. The exhaust manifold 35 includes a single exhaust passage 36 that communicates with the exhaust ports 22 and 22 and extends horizontally, and opens toward the other side of the cylinder head 4 in the exhaust passage 36. An exhaust pipe 37 disposed on the other side of the cylinder head 4 opposite to the carburetor 30 is connected to the downstream end of the exhaust manifold 35, and a muffler 38 is connected to the upper end of the exhaust pipe 37. Thus, as shown in FIGS. 2 and 3, the air cleaner 32 and the muffler 38 are disposed adjacently along the axis of the crankshaft 6 above the cylinder block 3 and the cylinder head 4.
[0020]
A fuel tank 41 adjacent to the air cleaner 32 and the muffler 38 is disposed above the crankcase 2 and supported by a bracket 40 protruding from the upper surface thereof (see FIGS. 1 and 3).
[0021]
4 and 8, an eccentric shaft portion 42 is formed at the center portion of the crankshaft 6, and a large end portion of a link 43 is rotatably fitted to the eccentric shaft portion 42, and a small end portion thereof is connected to the small end portion. Is connected to a balance weight 45 via a pivot 44 parallel to the crankshaft 6. The balance weight 45 is fixed to the inner wall of the crankcase 2 and extends parallel to the axis of the cylinders 18, 18. In addition, the guide hole 47 of the weight 45 is slidably fitted. The balance weight 45 reciprocates in the opposite direction to the pistons 17, 17 sliding inside the cylinders 18, 18 during operation of the engine E. At this time, the balance weight 45 substantially balances with the inertial force of both pistons 17, 17. It is designed to exert inertial force.
[0022]
The crankshaft 6 is divided into a crankshaft half 6A having an auxiliary machine mounting shaft 6a, a drive timing pulley 57 (described later) and an eccentric shaft 42, and a crankshaft half 6B having an output shaft 6o. Then, after assembling the link 43 to the eccentric shaft portion 42, the opposite end portions 6Aa and 6Ba of both the crankshaft halves 6A and 6B are press-fitted together.
[0023]
Thus, the engine E is configured as a parallel two-cylinder engine with an equidistant explosion by giving a phase difference of 360 ° to the pair of crank pins 6p, 6p of the crankshaft 6. Therefore, even if the displacement is increased, the vibration can be reduced by the dispersion of the explosion vibration, and the vibration of the engine E can be further reduced by the balance action of the inertia force between the balance weight 45 and the pistons 17 and 17. be able to. In addition, the intake and exhaust manifolds 27 and 35 are horizontally disposed above and below the inclined cylinder head 4, and the carburetor 30 and the exhaust pipe are disposed on opposite sides of the cylinder head 4. When the periphery of the cylinder head 4 is configured compactly, a large installation space for the air cleaner 32 and the muffler 38 can be secured above the cylinder block 3 and the cylinder head 4, which can contribute to the compactness of the engine E. In addition, heating of the intake system by the exhaust system can be avoided without using a special heat shield, which can contribute to simplification of the structure.
[0024]
Further, since the carburetor 30 is disposed so as to be adjacent to the cooling fan 12 connected to one end of the crankshaft 6 in the radial direction, the space around the cooling fan 12 can be effectively used as a space for installing the carburetor. Can contribute to further downsizing the engine E.
[0025]
Further, an air cleaner 32 and a muffler 38 are disposed adjacent to each other along the axial direction of the crankshaft 6 above the cylinder block 3 and the cylinder head 4, and a fuel tank 41 adjacent to the air cleaner 32 and the muffler 38 is disposed above the crankcase 2. Therefore, the space above the cylinder block 3, the cylinder head 4 and the crankcase 2 can be effectively used as a space for installing the air cleaner 32, the muffler 38 and the fuel tank 41, and the engine E can be made more compact. Can be achieved.
[0026]
Next, the lubrication system of the engine E will be described.
[0027]
4 and 8, the guide shaft 46, the balance weight 45, the pivot 44, the link 43, and the crank shaft 6 are formed with a series of lubricating oil passages 50 for supplying oil to the outer peripheral surfaces of the pair of crank pins 6p, 6p. In addition, a pump oil chamber 48 is provided in the middle of the lubricating oil passage 50. The pump oil chamber 48 is defined in the guide hole 47 of the balance weight 45 by the tip of the guide shaft 46, and expands and contracts as the balance weight 45 reciprocates.
[0028]
On the other hand, an oil pump 53 that is driven from the crankshaft 6 through driven and driven gears 51 and 52 is attached to the inner wall of the side cover 2b. A discharge port of the oil pump 53 and a guide shaft 46 are formed. The oil pipe 54 is connected to the inlet of the lubricating oil passage 50.
[0029]
Thus, during operation of the engine E, the oil pump 53 sucks the lubricating oil 56 stored in the bottom of the crankcase 2 through the strainer 55 and passes it through the oil pipe 54 and the lubricating oil passage 50 to the crank pins 6p and 6p. Supply and lubricate the rotating sliding surface between the connecting rods 16 and 16.
[0030]
At that time, the pump oil chamber 48 in the guide hole 47 repeats the expansion and contraction of the volume due to the reciprocating movement of the balance weight 45 and exhibits the pump action. At the time of the volume contraction, the discharge pressure of the oil pump 53 is reduced. Since the oil becomes a resistance and the reverse flow of oil is prevented, the oil pumped from the oil pump 53 can be effectively boosted and supplied to the crankpins 6p, 6p side, and the lubrication can be effectively performed. it can. Therefore, it is possible to use a small-capacity oil pump 53, and a special one-way valve for preventing backflow of oil is unnecessary, so that weight reduction and cost reduction can be achieved.
[0031]
Further, in the middle of the lubricating oil path 50, the sliding surface between the eccentric shaft portion 42 and the pivot 44 and the sliding surface between the guide shaft 46 and the balance weight 45 can be lubricated by the oil passing therethrough.
[0032]
Next, the valve train of the engine E will be described.
[0033]
4, 5, 9, and 10, a drive timing pulley 57 adjacent to the eccentric shaft portion 42 is formed at the center portion of the crankshaft 6. On the other hand, a cam support shaft 61 parallel to the crankshaft 6 is attached to the cylinder head 4, and the driven timing pulley 58 in the center of the cam shaft 62 that is rotatably supported by the cam support shaft 61 and the above drive. A timing belt 59 is stretched between the timing pulley 57. The drive and driven timing pulleys 57 and 58 and the belt 59 constitute a timing transmission device 60 that drives the camshaft 62 from the crankshaft 6 with a reduction ratio of 1/2.
[0034]
The camshaft 62 is formed with a pair of exhaust cams 66, 66 arranged with the driven timing pulley 58 interposed therebetween, and intake cams 65, 65 adjacent to the outer ends of the exhaust cams 66, 66. 65 is formed to have a smaller diameter than the inner exhaust cams 66, 66 so that the whole fits within the base circle of the inner exhaust cams 66, 66. The cam shaft 62 is arranged on one side of a plane P including both the axes of the intake valve 23 and the exhaust valve 24 so that the axis is substantially orthogonal to the plane P, and supports both ends of the cam support shaft 61. Therefore, the movement in the axial direction is restricted by the pair of support walls 67 and 67 formed in the cylinder head 4. A pair of small support walls 68, 68 are integrally connected to each of the support walls 67, 67. These small support walls 68, 68 are parallel to the cam spindle 61 and substantially perpendicular to the plane P. Both end portions of the rocker shaft 69 arranged in the same manner are supported. The rocker shaft 69 supports the intake rocker arm 70 and the exhaust rocker arm 71 so as to be individually swingable. That is, the intake rocker arm 70 and the exhaust rocker arm 71 are supported by one common rocker shaft 69.
[0035]
The intake rocker arm 70 is supported by rocker shafts 69 on opposite side walls of the base end portion, and a first arm 70a having a U-shaped cross-section whose front end abuts against the head of the intake valve 23 via an adjustment bolt 72. The second arm 70b extends from one side wall of the first arm 70a and slidably contacts the outer peripheral surface of the intake cam 65.
[0036]
The exhaust rocker arm 71 is supported by rocker shafts 69 on opposite side walls of the base end portion while covering the base end portion of the first arm 70a, and the distal end portion is connected to the head of the exhaust valve 24 via an adjusting bolt 73. The first arm 71a has a U-shaped cross section and comes into contact with the first arm 71a. The second arm 71b extends from one side wall of the first arm 71a and slidably contacts the outer peripheral surface of the exhaust cam 66.
[0037]
The intake and exhaust valves 23 and 24 are equipped with valve springs 74 and 75 for urging them in the valve closing direction.
[0038]
Each rocker shaft 69 has an enormous head 69a at an outer end facing the outside of the cylinder head 4, and the head 69a is connected to the cylinder head 4 so as to cover the valve system. It arrange | positions so that it may contact | abut on the inner surface. Therefore, when the head cover 76 is removed, the rocker shafts 69 and 69 can be inserted into and removed from the small support walls 68 and 68. However, when the head cover 76 is attached, the rocker shafts 69 and 69 are supported by the inner walls. Separation from the walls 68, 68 is prevented.
[0039]
A locking pin 77 is attached to the rocker shaft 69 between the small support walls 68, 68, and the locking pin 77 is inserted into the lateral hole 78 of the cam support shaft 61, and is removed from the support wall 67 of the cam support shaft 61. The withdrawal is prevented.
[0040]
Thus, when the camshaft 62 is rotationally driven from the crankshaft 6 via the timing transmission device 60, the intake and exhaust cams 65 and 66 individually drive the intake and exhaust rocker arms 70 and 71, and the valve spring 73. , 74, the intake and exhaust valves 23, 24 can be opened and closed at their own opening / closing timing.
[0041]
In addition, in the intake and exhaust rocker arms 70 and 71, the second arms 70b that are in sliding contact with the intake and exhaust cams 65 and 66, respectively, expect a step formed between the small-diameter intake cam 65 and the large-diameter exhaust cam 66. , 71b can be prevented from interfering with each other between the intake cam 65 and the exhaust rocker arm 71 and between the exhaust cam 66 and the intake rocker arm 70 by simply protruding the first arm 70a, 71a in the axial direction. The structure of the rocker arms 70 and 71 is not complicated.
[0042]
Further, since the intake and exhaust rocker arms 70 and 71 are supported by the common single rocker shaft 69, the number of parts can be reduced, and the assemblability can be improved and the cost can be reduced.
[0043]
Furthermore, by supporting both side walls of the base end of each of the first and second arms 70a, 71a having a U-shaped cross section of the intake and exhaust rocker arms 70, 71 on the rocker shaft 69, the support rigidity of the base ends is increased. Stable rocking of the rocker arms 70 and 71 can be ensured, and the base end portions of the rocker arms 70 and 71 are overlapped on the inside and outside, so that both the rocker arms 70 and 71 are compactly arranged, and the valve operating device is made compact. be able to.
[0044]
FIG. 11 shows a modified example of the engine of the present invention. The timing transmission device 60 is disposed adjacent to the inner wall of the side cover 2b, and the driven timing pulley 58 of the timing transmission device 60 is a cam spindle. Except that the cam shaft 62 is key-coupled to the cam support shaft 61 and the driven timing pulley 58 drives the cam shaft 62 via the cam support shaft 61. The configuration is the same as that of the embodiment, and in FIG. 11, the same reference numerals are assigned to the portions corresponding to those of the embodiment, and the description thereof is omitted.
[0045]
The present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the scope of the gist thereof. For example, in the camshaft 62, the larger diameter side may be the intake cam 65, the smaller diameter side may be the exhaust cam 66, and the exhaust rocker arm 71 may be disposed inside the intake rocker arm 70. The valve gear of the present invention can also be applied to a single cylinder engine.
[0046]
【The invention's effect】
As described above, according to the present invention, the common use of the rocker shaft with respect to the first and second rocker arms can reduce the number of parts, improve the assemblability and reduce the cost. By supporting both side walls of each base end of the rocker arm with a U-shaped cross section on the rocker shaft, the support rigidity of the base end can be increased, and stable rocking of each rocker arm can be ensured. By stacking the base end part inside and outside, both rocker arms can be arranged compactly and the valve operating device can be made compact.
[Brief description of the drawings]
FIG. 1 is a longitudinal side view of a main part of a general-purpose engine provided with a valve gear of the present invention.
FIG. 2 is a view taken in the direction of arrow 2 in FIG.
3 is a view taken in the direction of arrow 3 in FIG.
4 is a cross-sectional view taken along line 4-4 of FIG.
5 is a cross-sectional view taken along line 5-5 in FIG.
6 is a cross-sectional view taken along line 6-6 of FIG.
7 is a view taken in the direction of arrow 7 in FIG. 2;
8 is a cross-sectional view taken along line 8-8 in FIG.
9 is a cross-sectional view taken along line 9-9 in FIG.
FIG. 10 is a longitudinal sectional view (A), a left side view (B), and a right side view (C) showing a camshaft.
FIG. 11 is a longitudinal plan view showing a modification of the engine of the present invention.
[Explanation of symbols]
E ... Engine P ... Plane 23 ... Second valve (intake valve)
24 ...... First valve (exhaust valve)
62 ... Camshaft
65 ... intake cam
66 ... Exhaust cam 69 ... Rocker shaft 70 ... Second rocker arm (intake rocker arm)
71 ... 1st rocker arm (exhaust rocker arm)

Claims (1)

The axis is substantially perpendicular to the plane (P) on one side of the plane (P) including both the axes of the first valve (24) and the second valve (23) corresponding to one and the other of the intake valve and the exhaust valve. The cam shaft (62) is disposed, and the cam shaft (62) and the first valve (24) and the second valve (23) are disposed substantially perpendicular to the plane (P). The first and second valves (23) are connected to each other via a first rocker arm (71) and a second rocker arm (70) that are swingably supported by a rocker shaft (69). 24) In the valve operating device of the engine that is driven to open and close,
An intake cam (65) and an exhaust cam (66) are formed adjacent to the cam shaft (62), and one of the intake cam (65) and the exhaust cam (66) There is formed to fit within the base circle of the other cam, the tip portion of the first rocker arm (71), with U-shaped cross section opposing side walls of the base end is supported by the rocker shaft (69) Projecting from one side wall of the first arm (71a) in the axial direction of the camshaft (62) with the tip portion of the camshaft coming into contact with the head of the first valve (24) (62) and the second arm (71b) slidably contacting one of the cam surfaces of the intake cam (65) and the exhaust cam (66), and the second rocker arm (70) is the first rocker arm (71). ) On the inner side of the first arm (71a) of the base end portion having a U-shaped cross section. A first arm tip portion with the side walls are supported on the same said rocker shaft (69) abuts against the head portion of the second valve (23) (70a), from one side wall of the first arm (70a) The cam shaft (62) protrudes in the axial direction, and the tip end portion is composed of an intake cam of the cam shaft (62) and a second arm (70b) which is in sliding contact with the other cam surface of the exhaust cam. , Engine valve gear.

Images