JPH04284111A - Swing arm type valve system - Google Patents

Abstract

PURPOSE:To provide a swing arm type valve system capable of reducing the inertial mass of the movable part of a swing arm and increasing an engine speed more. CONSTITUTION:Pins 23 are inserted into connection holes 20d to 22d formed on the top end parts 20b to 22b of a high speed swing arm 21 and low speed arms 20, 22 so that the above high speed and low speed swing arms 20 to 22 are mutually connected rotatably. Cam shafts are provided in order to push respective swing arms 20 to 22, and the base end parts 20a to 22a of respective swing arms 20 to 22 are pivotally supported by high speed and low speed lash adjusters 44b, 44a. The to end parts 20b, 22b of the low speed swing arms 20, 22 are made to abut on a valve stem 14, while a part positioned on nearly the valve stem 14 side from the center of the connection hole 21d in the top end part 21b of the high speed swing arm 21 is cut so as to form the connection hole 21d in a semicircular shape.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a swing arm type valve train used in a four-stroke engine, and more particularly to an improved swing arm connection structure that can reduce inertial mass during valve opening and closing operations of the swing arm. .

0002

[Prior Art] Conventionally, there is a swing arm type valve train used in a four-stroke engine.
This is configured such that the base end of the swing arm is pivotally supported by a lash adjuster, the distal end is brought into contact with the valve stem, and the middle part of the swing arm is pressed by a cam. In such a swing arm type valve train, the inventors of the present invention,
The above-mentioned swing arm, lash adjuster, and cam are configured for high speed and low speed, and the tips of the high speed and low speed swing arms are rotatably connected with a pin, and
By applying hydraulic pressure to only one of the lash adjusters and fixing it, the swing arm can be switched between high speed and low speed, thereby controlling the opening/closing timing of the intake valve and the lift amount between high speed and low speed. We are developing a variable valve timing type valve train that can be switched.

0003

[Problems to be Solved by the Invention] However, the valve train according to the above development is configured so that by fixing only one of the lash adjusters, only the swing arm on that side can swing using this as a fulcrum. However, since the ends of both swing arms are connected to each other, the swing arm on the side to which the lash adjuster is not fixed also moves while being dragged by the swing arm on the other side. Therefore, there is a concern that the inertial mass of the movable portion of the swing arm becomes large, which is disadvantageous in increasing the speed of the engine. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a swing arm type valve train that can reduce the inertial mass of the movable part of the swing arm and can increase the speed of the engine.

0004

[Means for Solving the Problems] The present invention enables the high-speed and low-speed swing arms to rotate relative to each other by inserting a pin into a connecting hole formed at the tip of the high-speed swing arm and the low-speed swing arm. A camshaft is provided that presses both swing arms, and the base end of each swing arm is pivotally supported by high speed and low speed lash adjusters, and the base end of each swing arm is pivotally supported by high speed and low speed lash adjusters. The distal end of the first swing arm is brought into contact with the valve stem, and the valve stem side portion of the distal end of the other second swing arm that is not in contact with the valve stem is removed from approximately the center of the connecting hole. It is characterized by the connecting hole being formed in a semicircular shape.

[0005]

[Operation] According to the swing arm type valve train according to the present invention, when the first lash adjuster on the first swing arm side is fixed, the first swing arm swings about the first lash adjuster as a fulcrum, The tip of this opens and closes the valve. In this case, since the valve side portion of the second swing arm is cut away from the connection hole at the tip thereof, the second swing arm is disengaged from the pin as the first swing arm swings. It will not be dragged by the first swing arm. On the other hand, when the second lash adjuster on the second swing arm side is fixed, the second swing arm swings about the second lash adjuster, and this swing is transmitted to the first swing arm via the pin. , the first swing arm also swings, and the valve can be opened and closed without any trouble. In this way, in the present invention, the lower part of the tip of the second swing arm than the connecting hole is removed, so when the first lash adjuster is fixed, the second swing arm cannot be fixed.
The swing arm is not dragged by the first swing arm, and therefore the inertial mass can be reduced accordingly. In addition, if the second lash adjuster is fixed, the first lash adjuster
, both of the second swing arms swing, but the movable parts of the swing arms are lighter by the amount removed above, which also reduces the inertial mass, and these inertial mass reduction effects reduce the weight of the engine. This makes it possible to speed up the process. Note that in the above-mentioned cutting, the tip portion of the swing arm remote from the center is cut, not the swinging center side, so that the above-mentioned inertial mass is more effectively reduced.

[0006]

Embodiments Hereinafter, embodiments of the present invention will be explained with reference to the drawings. 1 to 7 are diagrams for explaining a swing arm type valve train according to an embodiment of the present invention, and FIGS.
are sectional views taken along lines I-I and II-II in FIG. 3, respectively, FIGS. 3 and 4 are a plan view and a side view of the embodiment device, FIG. 5 is a sectional side view of the lash adjuster, and FIG. 6 is a cross-sectional view of the switching device. FIG. 7 is a cross-sectional side view of an engine equipped with the device of this embodiment.

In the figure, 1 is 4 equipped with the device of this embodiment.
This is a four-valve cycle engine, and the engine 1 has a structure in which a cylinder head 4 is laminated and fastened to the upper surface of a cylinder block 2 into which a piston 3 is slidably inserted, and the upper surface of the cylinder head 4 is covered with a head cover 5. It is something.

A combustion chamber 6 is provided on the lower surface of the cylinder head 4.
The combustion chamber 6 is connected to an intake passage 8 and an exhaust passage 7 that open to the left and right wall surfaces of the cylinder head 4, respectively. Further, in the combustion chamber 6, two intake ports 8a and two exhaust ports 7a of the intake passage 8 and the exhaust passage 7 are opened per cylinder.
Valve heads 14b and 13b of the intake and exhaust valves 14 and 13 are located at a and 7a. Further, the valve stems 14a, 13a of the intake and exhaust valves 14, 13 extend upward, and a spark plug 9 is disposed in the center of the combustion chamber 6.
The cam chambers 10a and 10b are formed to sandwich the cam chambers 10a and 10b. Also, retainers 46 and 47 attached to the upper ends of each of the valve stems 14a and 13a and the cam chamber 10
A valve spring 48 is interposed between spring seats 10c formed on the valves 13 and 10b, and each of the valves 13 and 14 is biased in the closing direction.

An intake valve operating device 11 and an exhaust valve operating device 12 are disposed within the cam chambers 10a and 10b, respectively. The intake valve train 11 and the exhaust valve train 12 are
The base ends of the intake and exhaust swing arms 15 and 16 are pivoted by intake and exhaust lash adjusters 44 and 45, respectively, and the tips of the swing arms 15 and 16 abut against the upper ends of intake and exhaust valves 14 and 13. Furthermore, the suction and exhaust swing arms 15 and 16 are moved to the suction and exhaust camshafts 17.
, 18.

The lash adjuster 44 includes a high-speed adjuster (second adjuster) 44a and low-speed adjusters (first adjuster) 44b, 44 disposed on both sides of the high-speed adjuster (second adjuster) 44a.
b, and the low speed and high speed adjusters 4
4b and 44a are composed of a cylinder 30, a support piston 31 slidably inserted into the cylinder 30, and a switching valve 29 fixed to the lower part of the cylinder 30.

In FIG. 5 showing the high-speed lash adjuster 44a, the cylinder 30 has a cylindrical shape with a piston outlet hole 30a formed in the upper part and an oil hole 30b formed in the lower part. The support piston 31 is a rod-shaped member having a hollow portion 31c inside, and a pivot portion 31a is formed in a spherical shape at the upper end projecting outward. Further, a space surrounded by the bottom of the cylinder 30 and the lower end surface of the support piston 31 is a hydraulic operating chamber 51.
This hydraulic working chamber 51 and the hollow portion 31c are connected to the communication hole 31.
They are connected by f. And in this communication hole 31f part,
A check valve 52 formed by supporting a steel ball with a spring is provided. Further, a biasing spring 32 is interposed between the bottom surface of the cylinder 30 and the lower end surface of the support piston 31, thereby biasing the support piston 31 to the upper end position.

Further, oil grooves 30d and 31 are provided in the middle portions of the outer peripheral surfaces of the cylinder 30 and the support piston 31 in the height direction.
d is annularly recessed, and the oil grooves 30d and 31d communicate with the hollow portion 31c via communication holes 30c and 31e. A replenishment passage 50 is connected to the oil groove 30d and is formed in a straight line extending in the camshaft direction between the high speed and low speed adjusters 44a and 44b.

The switching valve 29 includes a valve cylinder 29a and a valve piston 2 slidably inserted into the valve cylinder 29a.
9b, and a biasing spring 29d interposed between the valve piston 29b and the valve cylinder 29a. An oil hole 29g is formed in the upper part of the valve cylinder 29a, and communicates with the hydraulic chamber 51 via the oil hole 29g and the oil hole 30b. In addition, the valve cylinder 29
A high-pressure oil hole 29e and a low-pressure oil hole 29f are formed in the lower part of a. Note that 29c is a lid that closes the opening of the valve cylinder 29a.

Oil passages 33 to 35 are formed below the high speed and low speed adjusters 44a and 44b of the cylinder head 4 so as to extend in the crankshaft direction. The high-pressure oil hole 29e of the high-speed adjuster 44a communicates with the oil passage 33, and the low-pressure oil hole 29f communicates with the oil passage 34. Also, the high pressure and low pressure oil holes 29e of the low pressure adjuster 44b
, 29f communicate with oil passages 35 and 34, respectively. Note that the oil passage 34 is open to an oil pool.

One end of the oil passages 33, 35 is connected to a hydraulic pump, and the other end is connected to a switching device 36 for opening and closing the oil passages 33, 35. The switching device 36 includes a housing 39 that is always maintained at a low pressure, and a housing 39 that is kept at low pressure at all times.
9, a piston 41 slidably inserted into the cylinder 40, and the piston 41.
a spring 43 that urges the housing 39 to the left in the figure;
The solenoid 42 is attached to the piston 41, and its piston rod 42a is in contact with the piston 41. The oil passages 33, 35 are connected to holes 37, 38 formed in the cylinder 40 and holes 41b, 41 in the piston 41.
It is possible to communicate with the inside of the housing 39 through a. When the solenoid 42 is turned off, the piston 41 is located at the position shown in the figure, thereby holding the oil passage 33 at high pressure and opening the oil passage 35. When the solenoid 42 is turned on, the piston 41 moves forward and the oil passage 35 is opened. The pressure is maintained at high pressure, and the oil passage 33 is opened.

The intake swing arm 15 includes a high speed arm (second swing arm) 21 and low speed arms (first swing arm) 20 and 22 disposed on both sides of this arm.
It is made up of. The low-speed arms 20 and 22 have the same length, and a roller 24 is rotatably disposed at the center in the longitudinal direction. Further, the high-speed arm 21 is shorter than the low-speed arms 20 and 22, and a slipper 25 is fixed to the center thereof. The tips 20b, 21b, 22b of these arms 20-22 are rotatably connected to each other by the following structure. That is, a semicircular connecting recess 21d is formed at the tip of the high-speed arm 21. This can be formed, for example, by cutting off a portion of the tip of a conventional swing arm having a circular connecting hole formed therethrough, below the center of the connecting hole. Furthermore, circular connecting holes 20d and 22d are formed through the tips of the low-speed swing arms 20 and 22. Then, the connecting pin 23 is inserted and fixed into the connecting holes 20d and 22d of the low-speed arms 20 and 22, and the connecting recess 21d of the high-speed arm 21 is placed over the center of the connecting pin 23, thereby connecting the three arms 20 to 22. Connect 22. In addition, 2
3a is an oil groove recessed in the center of the connecting pin 23.

[0017] Furthermore, the base end portion 2 of each of the arms 20 to 22 is
0a, 21a, 22a have the above lash adjuster 44.
Support holes 20c, 21c, and 22c are formed, respectively, to be supported by the pivot portion 31a of a or 44b. And the tips 20b, 22 of the low speed arms 20, 22
The lower surface b is flat, and the flat surface abuts the upper end surface of the valve stem 14a of the intake valve 14. In addition, 26 is a lubricating oil passage, which allows the lubricating oil in the support piston 31 to be connected to the connecting recess 21d, the connecting hole 20d, and the connecting hole 20d.
This is for introducing into 2d.

A cam shaft 17 for driving the intake swing arm 15 is formed with a high speed cam 17a and a pair of low speed cams 17b, and the high speed cam 17a is connected to the slipper 25 of the high speed arm 21. The low speed cams 17b, 17b are in sliding contact with the low speed arms 20, 22.
The rollers 24, 24 are in rolling contact with each other.

Next, the effects of this embodiment will be explained. When the engine rotates at high speed, the switching device 36 closes the oil passage 33. Then, the oil pressure in the oil passage 33 increases, the valve piston 29b of the high-speed adjuster 44a moves forward and closes the communication hole 29g, and the hydraulic oil in the hydraulic chamber 51 is prevented from flowing out, and the support piston of the high-speed adjuster 44a moves forward. 31 supports the high speed arm 21. As a result, the high-speed arm 21 swings about the high-speed adjuster 44a, and this swing is transmitted from the connecting recess 21d to the low-speed arms 20, 22 via the connecting pin 23.
The tip portions of 0 and 22 drive the intake valve 14 to open and close. As a result, the intake valve 14 opens and closes the intake port 8a with a lift amount and opening/closing timing according to the shape of the high-speed cam 17a and the arm ratio of the high-speed arm 21.

Further, during low speed rotation, the switching device 36 opens the oil passage 33 and closes the oil passage 35. Then, the pressure inside the oil passage 35 increases, and the low speed adjuster 44b
The support piston 31 is fixed, so that the low-speed arms 20, 21 swing about the low-speed adjuster 44b as a fulcrum. As a result, the intake valve 14 has a low speed cam 17b.
The air intake port 8a is opened and closed at a lift amount and opening/closing timing according to the shape of the air intake port 20 and the arm ratio of the low-speed arms 20 and 22. In this case, the high-speed arm 21 is locked with the connecting recess 21d and the connecting pin 23 as the low-speed arm 20,
Because it comes off as the arm 22 swings, the low-speed arm 20
, 22, and the low speed arm 20
, 22 will not be affected.

As described above, in the device of this embodiment, the semicircular connecting recess 21d is formed by cutting off the lower part of the tip of the high-speed arm 21, and this is made to cover the connecting pin 23. , if the low speed adjuster 44b is fixed during low speed rotation, the low speed arms 20, 2
Therefore, when looking at the swing arm 15 as a whole, the inertial mass in the opening/closing operation of the intake valve 14 is significantly reduced, and the followability of the valve opening/closing operation is improved. This is advantageous in terms of speeding up the process.

Furthermore, during high-speed rotation, the high-speed adjuster 44a is fixed and the swinging motion of the high-speed arm 21 is transmitted to the low-speed arms 20, 22 via the connecting pin 23, so that all the arms 20 22 swings, which opens and closes the intake valve 14. Since the connecting recess 21d of the high-speed arm 21 is semicircular, the tip of the arm is made smaller compared to a conventional swing arm. The weight is reduced, so the inertial mass can be reduced even during high-speed rotation. In this case, since the tip portion of the high-speed arm 21 in its swinging motion is lightened, the effect of reducing the inertial mass becomes significant, which is also advantageous in increasing the speed of the engine.

In the above embodiment, the high speed arm 21
Although the weight of the tip of the arm is reduced by making the connecting hole semicircular, the present invention can also be applied to a low-speed arm. To apply it to a low-speed arm, high-speed arms are arranged on both sides in FIG. 3, and the lower surface of the tip thereof is brought into contact with the intake valve 14. Further, a low-speed arm is arranged in the center, and a semicircular connecting recess is formed at the tip of the low-speed arm. Further, in the above embodiment, the case where there are two intake valves has been described, but the present invention can be applied regardless of the number of intake valves, and of course can also be applied to a valve train on the exhaust valve side.

[0024]

As described above, according to the swing arm type valve train according to the present invention, the lower part of the tip of the second swing arm that does not come into contact with the valve, below the connecting hole, can be removed to connect the connecting pin. Since the lock can be released, the inertial mass of the swing arm in the valve opening/closing operation can be significantly reduced, the followability of the opening/closing operation can be improved, and the engine speed can be increased.

[Brief explanation of the drawing]

FIG. 1 is a sectional view taken along line II in FIG. 3;

FIG. 2 is a sectional view taken along line II-II in FIG. 3;

FIG. 3 is a plan view of a valve train according to an embodiment of the present invention.

FIG. 4 is a side view of the apparatus of the embodiment.

FIG. 5 is a cross-sectional side view of the lash adjuster of the embodiment device.

FIG. 6 is a cross-sectional plan view of the switching device of the embodiment device.

FIG. 7 is a cross-sectional front view of a cylinder head portion of an engine equipped with the above embodiment device.

[Explanation of symbols]

11 Swing arm type valve train 14b Valve stem 17 Camshafts 20, 22 Low speed arm (first wing arm) 20
a, 22a Base end portions 20b, 22b Tip portions 20d, 22d Connection hole 21 High speed arm (second swing arm) 21a
Base end portion 21b Tip portion 21d Connection recess (semicircular connection hole) 23 Connection pin 44a High speed lash adjuster 44b Low speed lash adjuster

Claims (1)

[Claims] Claim 1: The high speed and low speed swing arms are rotatably connected to each other by inserting a pin into a connecting hole formed at the tip of the high speed swing arm and the low speed swing arm, and the high speed swing arm and the low speed swing arm are rotatably connected to each other. A camshaft is provided to press the
The base end of each swing arm is pivoted by a lash adjuster, and the tip of either the high speed or low speed first swing arm is brought into contact with the valve stem. A swing arm type valve operating device characterized in that the connecting hole is formed in a semicircular shape by cutting a portion of the distal end of the other second swing arm closer to the valve stem from approximately the center of the connecting hole.