JPS6223513A - Mechanical type automatic decompressor for starting engine - Google Patents

Abstract

PURPOSE:To enable decompression to be achieved with simple construction, by providing a movement receiver piece making turning movement against a torsion spring simultaneously being thrust upward by a tappet with a protrusive piece when the tappet is operated by the protrusive piece for decompression provided on a camshaft. CONSTITUTION:A protrusive piece 3 for decompression which opens an exhaust valve in a time of a compression stroke is provided on a camshaft 2 adjacent to a normal exhaust cam 16. When an engine is in low speed, a movement receiving piece 5 at the lower surface of a tappet 4 is given turning movement against a torsion spring 6, being thrust upward by the protrusive piece 3 so that decompression is carried out by the upward thrust. In a low speed rotation, nevertheless the turning movement of the movement receiving piece 5, the protrusive piece 3 returns in the original position before it comes again in a position for thrusting the movement receiving piece 5 upward, so that decompression is carried out again. In a high speed rotation, the protrusive piece 3 comes in the position thrusting the movement receiving piece 5 upward but the said piece 5 has not returned, so that decompression operation is not carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention provides a method for reducing the starting torque of an engine.
To provide a predetermined type decompression device which improves decompression accuracy while maintaining high strength of a camshaft, and which can be installed on either side of an intake or exhaust system without being restricted by the position of a cam gear.

Prior Art The basic structure of the mechanical automatic depressing device for engine starting, which is the subject of the present invention, is that a decompressing device 3 is attached to the camshaft 2 of the valve train 1 of the engine E, and the decompressing device 3 is attached to the camshaft 2 of the valve train 1 of the engine E. At the beginning of the rotation, the decompression valve 3 or the tappet 4 of the decompression valve is driven to defump the cylinder chamber, and at the end of the starting rotation, the decompression valve 3 stops driving the tappet 4 and the defumping is released. This is a form of Rano.

A conventional example of this type is, for example, in 1977, in which a centrifugal weight was pivoted so that it could swing freely, and a pin guide hole was formed in the wall of the valve camshaft from the cam gear to the cylindrical area near the intake and exhaust cams. penetrate,
A defumping pin is slidably inserted into the bottle guide hole to form a defumping tool, the input end of the decompression tool is interlocked with the output end of the centrifugal weight, and the output end is connected to the tappet of the defumping valve. There is something that seems to be the case.

<Problem to be solved by the invention> However, in the above-mentioned prior art, the decompression device has four components: the cam gear, the centrifugal weight, its fulcrum pin, and the decompression bin, and the centrifugal weight and the decompression pin move among these. When manufacturing and assembling these parts, there is a large margin for manufacturing and assembly errors due to the large number of component parts. Since there is a possibility that this may occur, the defumping accuracy will deteriorate as a whole.

In addition, the strength of the camshaft is reduced due to the installation of the bottle guide hole in the camshaft, and in order to compensate for this reduction, the camshaft must be replaced with a larger diameter camshaft and the centrifugal weight must be made thicker. This inevitably leads to an increase in the size of the engine.

Moreover, for example, in a gasoline engine in which a cam gear, an intake cam, and an exhaust cam are sequentially provided on the valve camshaft,
Since the conventional technology uses the cam gear as one component, the defumping operation is performed on the intake cam side near the cam gear, so the air-fuel mixture repeatedly enters and exits the combustion chamber and the intake passage, reducing its concentration. Excessive amounts will make combustion difficult and reduce starting performance.

The technical object of the present invention is to solve the above problems.

Means for Solving the Problems> Means for solving the above problems will be described below with reference to FIGS. 1 to 9, which correspond to embodiments.

That is, the decompression device 3 is fixed to protrude from the circumferential surface of the camshaft 2, and the decompression passive force 5 is protruded outside the circumference of the tappet 4 so as to be movable together in the valve opening/closing direction A.
The passive side surface 7 of the passive soldier 5 is made to be freely rotatable around the center 8, and held in the decompression passive position P by the tension of the return spring 6.
A part of the decompressor 3 is configured to be located within the rotation space B of the decompressor 3.

<Function> As the valve camshaft 2 rotates, when the decompression soldier 3 comes into contact with the decompression passive device 5, the decompression passive device 5 is returned and pushed in the direction of rotation of the valve camshaft 2 against the tension of the spring 6. Trying to move up.

Therefore, when the engine is in a low rotation range, the defump passive device 5 receives the push and turn from the decompression device 3 and rotates at a small angle along the narrow 8th circumference of the tappet, so that the next contact is prevented. Return to that position by the time you receive it.

Therefore, the tappet '1 rises by the amount by which the decompression tool 3 protrudes, thereby smoothly performing the decompression operation.

On the other hand, when the engine speeds up to high speeds, the decompressor is activated.

3's push-up rotational force increases, forcing the decompression passive tool to rotate a little, and the contact synchronization of decomp soldier 3 becomes shorter, so passive soldier 5 cannot return to its original position.

Therefore, the tappet 4 is not pushed up by the defump tool 3, and the defump operation is smoothly released.

<Effects of the invention> This decompression device has two functions: a decompression soldier and a decompression passive.
Since these two components are not moving parts, there is less room for manufacturing errors and assembly errors when manufacturing and assembling these parts, as the number of parts is smaller than in conventional examples. In addition, since there are no moving parts, interlocking errors can be eliminated, so overall decompression accuracy can be increased.

In addition, it causes decompression odor to protrude on the circumferential surface of the camshaft.
There is no need to fit the decompression tool onto the camshaft as in the conventional example.

Therefore, since there is no insertion hole, the diameter of the decompression shaft is increased a/l.
vinegar.・/ ]-]1i! #r1r-t, half n! -1lg/7'l fJ T: It can be made compact and meet the needs for miniaturization, which is a recent trend.

Moreover, in the present invention, since the decompression device does not include a cam gear as one of its constituent elements, it is not restricted to the position of the cam gear and can be attached to either side of the intake or exhaust system.

In other words, even in an engine where the exhaust cam is separate from the cam gear, decompression can be easily performed in the exhaust system, so even if the intake system is adjacent to the cam gear as in the conventional example, decompression can be applied to the intake system. The system of operation is not limited, and the intake can be performed smoothly to improve starting performance.

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

Figure 1 is a longitudinal sectional front view of the main parts around the valve camshaft, Figure 2 is a perspective view of the main parts around the tappet, Figure 3 is a plan view thereof, and Figure 4 is a front view of the main parts around the valve camshaft.
The figure is a front view, and FIG. 5 is a left side view thereof, in which a crankshaft 11 is mounted in the center of a crankcase 10 of an overhead valve engine E, and a valve train 2 is mounted in parallel above the crankshaft 11. Then, the crank gear 12 and the cam gear 14 are engaged to interlock the valve drive camshaft 2 with the crankshaft 11.

The valve train 1 consists of an intake/exhaust valve (not shown), intake/exhaust tappets 4, 4, and a valve camshaft 2. The intake/exhaust tappets 4, 4 are driven up and down by the vertical movement, and the intake/exhaust valves can be opened/closed by the vertical movement.

A decompression tool 3 with a spherical tip is driven into a protruding position between the intake and exhaust cams 5 and 16 of the valve drive camshaft 2, and the rotation space of the decompression tool 3 is protruded. Face part of exhaust tappet 4 so as to be located within B〕7
A flat defump receiver 5 is integrally connected to the flat defump receiver 5.

A locking protrusion 18 is provided on the upper surface of the 7-chair portion 17 of the exhaust tappet 4.
is erected, and a spiral spring 6 is attached between the protrusion 18 and a fixing part 19 provided on the crankcase 10 to urge the face part 17 in the R direction.

Incidentally, reference numeral 20 is a rotation limit stopper of the tappet.

In this case, when the valve drive camshaft 2 rotates downward, the decompression tool 3 contacts and raises the defump passive tool 5, and rotates the exhaust tappet 4 downward along its axis S.

However, since the X-wound spring 6 biases the exhaust tappet 4 in the R direction (that is, the opposite direction of T), the exhaust tappet 4 is constantly subjected to a force that tends to return to its original position.

Therefore, when the engine speed is low, it takes a long time for the defumping device 3, which has once been pushed up, to make one rotation and return to the contact position of the defumping passive device 5. The tappet 4 returns to its original position, and its passive tool 5 is positioned within the rotation space B of the decompression tool 3.

Therefore, the exhaust tappet 4 continues to be pushed up when it comes into contact with the defumping tool 3, so that the decompression state is maintained (see FIGS. 2 to 5).

On the other hand, as the differential pump rotation speed increases, the time required for the differential pump 3 to rotate once becomes shorter, and the differential pump tool 3 passes the contact position before the downwardly rotated exhaust table 4 can fully return. Therefore, the passive tool 5 is positioned outside the rotation space B of the decompression tool 3.

Therefore, the exhaust tappet 4 is not touched by the decompression soldier 3 and is not pushed up, so that the decompression state is quickly released (see FIGS. 6 and 7).

FIGS. 8 and 9 show an embodiment of the pond according to the present invention.
A guide 24 with screws secured to the bottom plate 22 is rotatably attached to the 7-wheel chair part 17 of the tappet 1, and a decompression passive device 5 is connected to the bottom plate 22, and this passive device 5 and the fixing portion of the crankcase are connected to each other. A spiral spring 6 for return is inserted between the two.

Therefore, in the above embodiment, the passive tool 5 that is contacted by the decompression soldier 3 rotates separately from the face portion 17.

As described above, in the present invention, the decompression device 3 is protruded from the camshaft 2, and the decompression passive device 5 is provided protruding outside the periphery of the tappet 4. Therefore, the tappet provided with the passive device 5 is similar to the above embodiment. Although there is a problem with starting performance not only for exhaust tappets, it can also be applied to intake tappets.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a longitudinal sectional front view of the main parts around the valve camshaft, FIG. 2 is a perspective view of the main parts around the tappet, FIG. 3 is a plan view thereof, and FIG. Its front view, FIG. 5 is its left side view, FIG. 6 is a view equivalent to FIG. 3 showing the decompression release state, FIG. 7 is a view equivalent to FIG. 2 showing the same state, and FIG. 8 is another embodiment. FIG. 9 is an enlarged front view of the main part of the tapest illustrating the same embodiment. 1... Valve train, 2... Camshaft, 3... Decompression tool, 4... Tappet, 5... Defumping passive device, 6... Return spring, A... Valve opening/closing direction,
B...Rotating space of 3, E...Engine, P.
... Decompression passive position of 5, around the axis of S...4. Figure 5 Figure 4 Figure 3 Figure 2 Figure 1 Figure 6' Knee Figure 8 Figure 9

Claims (1)

[Claims] 1. A decompressor 3 is attached to the camshaft 2 of the valve train 1 of the engine E.
At the beginning of the starting operation rotation of the engine E, the decompression tool 3 drives the tappet 4 of the decompression valve to decompress the cylinder chamber, and at the end of the starting operation rotation, the decompression tool 3 drives the tappet 4. In a mechanical automatic decompression device for starting an engine configured to release the decompression, the decompression tool 3 is fixed so as to protrude onto the circumferential surface of the camshaft 2, and the decompression passive device 5 is placed outside the periphery of the tappet 4 in the valve opening/closing direction. The passive device 5 is provided in a protruding manner so as to be movable together with the tappet 4, so that the passive device 5 can freely rotate back and forth around the axis S of the tappet 4, and is held at the decompression passive position P by the tension of the return spring 6, so that the passive device 5 is in the decompression passive position. An automatic mechanical decompression device for starting an engine, characterized in that it is configured to be located on the passive side of the passive device 5 in the state of P.