JPH032650Y2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Field of Industrial Application The present invention relates to a valve train for an automobile engine, etc., which has a function of automatically changing the valve timing of an intake valve.

(B) Prior art A typical reciprocating engine in which the intake valve closes at an earlier timing (see broken line a in Figure 1) has standard valve timing (see solid line b in Figure 1). ), it is possible to obtain higher engine torque in the low speed rotation range, but there is a tendency for the torque to drop significantly in the medium to high speed rotation range. On the other hand, the timing of closing the intake valve is set later (see the dashed line c in Figure 1).
Compared to those with standard valve timing, there is less torque drop in the medium to high speed range, but there is a tendency that sufficient torque cannot be obtained in the low speed range. Therefore, in order to obtain high torque over the entire rotational speed range, the valve train for driving the intake valves must have a function that advances or retards the valve timing according to the engine rotational speed. desirable.

As a prior art related to a valve train developed to meet such demands, as shown in the previously filed Japanese Patent Application No. 58-139844 (see Japanese Patent Application Laid-Open No. 60-30408), The rotational force of the shaft is transferred to the camshaft that opens and closes the intake valve.
Pulleys supported by both shafts,
In a device in which transmission is transmitted via a pair of transmission members such as sprockets or gears, at least one transmission member is connected to a first rotating body fixed to the shaft, and to the first rotating body. a second rotating body that is movable in the axial direction and has a transmission element on its outer periphery; and a second rotating body that is provided on opposing surfaces of both rotating bodies, and at least one of which becomes gradually shallower toward the outer end. a pair of cam grooves formed as shown in FIG. and an elastic body that centripetally urges the weight toward the inner end of the deepened cam groove, and the outward movement of the weight due to centrifugal force changes the phase of the two rotating bodies. There are some that are configured so that they can be changed mutually. However, such a device is disadvantageous in that rust and wear easily occur in the sliding portion between the weight and the inner surface of the cam groove, resulting in malfunction. In order to solve this problem, it may be possible to supply lubricant to the sliding parts, but if this is the only method, the lubricant will scatter outward due to centrifugal force, and the lubricant effect and rust prevention will be affected. There is a problem that the effect cannot be maintained for a long period of time. In addition, if a rubber timing belt or the like is wrapped around the outer circumference of the rotating body,
There is also the problem that the scattered lubricating oil adheres to the timing belt and the like, significantly reducing its durability.

(C) Purpose The present invention was developed in light of the above circumstances, and has a simple structure in which a weight fitted into a cam groove is actuated by centrifugal force, and the valve timing is adjusted to the engine speed. The lubricant supplied to the sliding portion between the cam groove and the weight can be effectively prevented from scattering outward due to centrifugal force.
It is possible to maintain the lubricating effect and anti-corrosion effect in these parts over a long period of time, and it also eliminates the problem of scattered lubricant adhering to the timing belt etc. and reducing its durability. The object of the present invention is to provide a valve device.

(D) Structure In order to achieve this object, the present invention provides a pair of annular sealing members that close the gap formed between the two rotary bodies on the inner circumferential side of the cam groove. and a lubricant is injected between these two sealing materials.

(E) Embodiment Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 2 to 7.

Timing pulleys 3 and 4, which are transmission members, are mounted on the crankshaft 1 and camshaft 2 of the engine, respectively, and these pulleys 3,
A timing belt 5 is stretched between the belts 4 and 4, and the rotational force of the crankshaft 1 in the direction of arrow X is transmitted to the camshaft 2 via the pulley 3, belt 5, and pulley 4. Note that the timing pulley 3 on the drive side is a normal one,
It is fixed to the crankshaft 1 via a key 6. On the other hand, the timing pulley 4 on the driven side is connected to a first rotating body 7 fixed to the camshaft 2.
, a second rotating body 8 provided so as to be movable in the axial direction with respect to the first rotating body 7, and a pair of cam grooves 9 provided on opposing surfaces of both of these rotating bodies 7, 8, respectively. 10, a steel ball 12 as a weight engaged between both the cam grooves 9 and 10, and a wave spring 13 as an elastic body that presses both the rotating bodies 7 and 8 in the direction toward each other. Become. The first rotating body 7 consists of a hub 7a that fits on the outer periphery of the end of the camshaft 2, and a disk portion 7b that projects from the outer periphery of the hub 7a. and is fixed to the camshaft 2 using bolts 15. Further, the second rotating body 8 is a hub 7 of the first rotating body 7.
a disc portion 8a rotatably fitted to the outer periphery of a;
A cylindrical portion 8 integrally formed on the outer periphery of this disk portion 8a
A transmission element, that is, teeth 8c with which the timing belt 5 meshes are provided on the outer periphery of the cylindrical portion 8b. The cam groove 9 is oval-shaped and is provided in the end surface of the disk portion 7b of the first rotary body 7 in a substantially radial direction, so that one half of the ball 12 can fit into the cam groove 9. The cross section is shaped like a semicircular arc. This cam groove 9 is
It is set to become gradually shallower from the inner end 9a to the outer end 9b. Further, the cam groove 10
is an oval shape provided in a portion of the disc portion 8a of the second rotating body 8 corresponding to the cam groove 9, and has a cross section so that the other half of the ball 12 can fit therein. It is shaped like a semi-circular arc. The cam groove 10 is also set to become gradually shallower from the inner end 10a to the outer end 10b. Note that the directions in which the cam grooves 9 and 10 are carved are slightly different from each other. That is, in this embodiment, in a state where the ball 12 is held at the inner end 9a, 10a of each cam groove 9, 10,
The outer end 9b of the cam groove 9 is set to be shifted by a required amount in the direction of rotational advancement than the outer end 10b of the cam groove 10. Note that 16 is a snap spring for locking the wave spring 13. In addition, the cam grooves 9 and 10 and the ball 1
2, a plurality of sets (for example, 3 to 6 sets) are provided at equiangular intervals in the circumferential direction.

Further, a pair of annular sealing members, for example, O-rings 18 and 19, which close this gap 18, are placed in the gap 17 formed between the two rotary bodies 7 and 8, which is inner than the cam grooves 9 and 10. They are placed on the circumferential side and on the outer circumferential side, respectively. Specifically, the inner O-ring 18 is fitted in an annular groove 21 provided on the outer circumferential surface of the hub 7a of the first rotating body 7, and is fitted in an annular groove 21 provided on the outer circumferential surface of the hub 7a of the first rotating body 7. Closely attached to the inner surface. Further, the O-ring 19 on the outer circumferential side is installed in an annular groove 22 provided on the outer circumferential surface of the disc portion 7a of the rotary body 7, and is in close contact with the inner circumferential surface of the cylindrical portion 8b of the rotary body 8. There is. A small amount of lubricant 23 is sealed between these O-rings 18 and 19.

With such a configuration, the centrifugal force acting on the ball 12 is small in the low-speed rotation range where the rotational speed of the crankshaft 1 and the camshaft 2 is low, so that the ball 12 is rotated as shown in FIGS. 3 and 4. As shown in FIG. 2, the cam grooves 9 and 10 are held at the inner ends 9a and 10a of each cam groove 9 and 10, respectively. That is, since the first rotary body 7 and the second rotary body 8 are biased in the opposite direction by the elastic force of the wave spring 13, the ball 12 is pushed into the two cam grooves 9, These cam grooves 9 and 10 are designed to become gradually shallower toward the outer ends 9b and 10b. Therefore, a centripetal force acts on the ball 12 due to the clamping pressure and the change in the depth of the cam grooves 9, 10, and in a low speed rotation range where the centripetal force overcomes the centrifugal force, the ball 12 is the cam groove 9, 10
It will be held at the inner ends 9a, 10a. When the rotational speed of the engine increases from this state and the centrifugal force acting on the ball 12 exceeds a certain value, the ball 12 expands the distance between the two rotating bodies 7 and 8 and moves outward of the cam grooves 9 and 10. Ends 9b, 10
It moves in direction b and is held at a position that balances the centripetal force described above. At this time, due to the difference in the inclination of the two cam grooves 9, 10 in the rotational direction, both the rotating bodies 7, 8
A phase difference occurs between the two, and the valve timing is delayed by that amount. When rotating at the highest speed, as shown in the imaginary line in FIG. 3 and in FIG.
b, 10b, and the valve timing becomes the most delayed state. When the speed is decelerated from this state, the centrifugal force acting on the ball 12 decreases, and the ball 12 is returned toward the inner ends 9a, 10a by the centripetal force generated by the wave spring 13 described above. FIG. 6 shows the relationship between the rotational speed of the crankshaft 1 and the valve timing in this embodiment.
The figure shows the difference between valve timing in a low speed rotation range and valve timing in a high speed rotation range.

As described above, according to the valve train according to the present invention, the pressing force of the wave spring 13 and the cam grooves 9, 10
By appropriately selecting the shape, etc. of the intake valve, the valve timing of the intake valve can be automatically controlled. However, as in this embodiment, it is easy to control the valve timing to retard the transition from a low speed rotation range to a high speed rotation range, and in this way, the intake inertia can be utilized. Since the closing timing of the intake valve can be delayed only in the high-speed rotation range where it is possible, the output characteristics in the high-speed rotation range can be effectively improved without deteriorating the performance in the middle and low speed rotation ranges. Moreover, this valve train has a very simple structure with a small number of parts, and can be expected to operate reliably. Moreover, there is no need to perform any special processing on the camshaft 2, etc. Therefore, it is possible to reduce costs by increasing the proportion of common parts with standard engines that do not have a valve timing control function, and it can also be easily applied to existing engines by simply replacing the pulleys. It has the advantage of being able to

Furthermore, this thing has a pair of O-rings 18,
Since the sliding parts between the cam grooves 9 and 10 and the weight 13 are lubricated by the lubricant 23 sealed between the parts 19 and 19, rust and wear can be effectively prevented from occurring in the sliding parts. The above-mentioned operation can be performed smoothly and reliably. Furthermore, the lubricant 23 injected between the O-rings 18 and 19 does not scatter outward even when centrifugal force is applied, so the aforementioned lubricating effect and anti-corrosion effect can be maintained for a long period of time. Furthermore, there is no problem in that the lubricant 23 that has spread out adheres to the timing belt 5 and impairs its durability.

In addition, in the above embodiment, the case where the shape of the cam groove is set so as to retard the valve timing in the high-speed rotation range has been described, but the present invention is of course not limited to such a configuration. For example, various modifications are possible, such as retarding the valve timing only in the idling operating range, or in the idling operating range and in the high speed rotation range.

Further, in the above embodiment, the transmission member is a timing pulley on the camshaft side, but the present invention is of course not limited to this, and can be applied to a pulley on the crankshaft side, for example. You can. Alternatively, instead of a pulley, the present invention can be similarly applied to a sprocket, gear, etc. for tensioning a chain.

Furthermore, the weight is not limited to a ball, but may also be a roller or the like.

Further, the arrangement position of the sealing material is not limited to that in the above embodiment, but may be as shown in FIG. 8, for example. That is, what is shown in FIG.
A pair of annular grooves 21' and 22' are provided on the front end surface of the disc portion 7b of the rotating body 7, respectively, and are located on the inner and outer circumferential sides of the cam grooves 9 and 10, respectively. , 22' are fitted with O-rings 18', 19' which serve as sealing materials that also come into close contact with the second rotating body 8.

Note that the sealing material is not limited to an O-ring, but may be other materials.

(f) Effect Since the present invention has the above-mentioned configuration, it is possible to change the valve timing according to the engine speed using the simple principle of operating the weight fitted in the cam groove by centrifugal force. In addition, it is possible to effectively prevent the lubricant supplied to the sliding part between the cam groove and the weight from scattering outward due to centrifugal force, thereby improving the lubrication effect and rust prevention in the sliding part. It is possible to provide an engine valve train that can maintain its operation over a long period of time and eliminate the inconvenience of scattered lubricant adhering to a timing belt and reducing its durability. .

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the relationship between engine torque and rotational speed. Figures 2 to 7 show an embodiment of the present invention; Figure 2 is a partially cutaway front view, Figure 3 is an enlarged side sectional view showing the main parts, and Figures 4 and 5 are FIG. 6 is a characteristic diagram showing retard characteristics, and FIG. 7 is a diagram showing valve timing. FIG. 8 is a side sectional view corresponding to FIG. 3 showing another embodiment of the present invention. 1... Crankshaft, 2... Camshaft, 4... Transmission member (timing pulley), 7...
...First rotating body, 8... Second rotating body, 9, 10
...Cam groove, 12 ... Weight (ball), 13
...Elastic body (wave spring), 17...Gap, 18, 18', 19, 19'...Sealing material (O-ring), 23...Lubricant.

Claims (1)

[Scope of utility model registration request] In a system in which the rotational force of a crankshaft is transmitted to a camshaft for opening and closing intake valves via a pair of transmission members such as pulleys, sprockets, or gears supported by both shafts, at least one of the transmission members a first rotating body fixed to the shaft; a second rotating body that is movable in the axial direction with respect to the first rotating body and has a transmission element on its outer peripheral portion; A pair of cam grooves are provided on the opposing surfaces of both rotating bodies, and at least one of the cam grooves is formed to become gradually shallower toward the outer end. and an elastic body that presses both the rotating bodies in a direction toward each other and centripetally biases the weight toward the inner end side of the deepened cam groove. The structure is configured so that the phases of the two rotating bodies can be mutually changed by the outward movement of the weight due to centrifugal force, and the gap formed between the two rotating bodies has this gap. An engine characterized in that a pair of annular sealing members for closing the cam grooves are interposed, respectively, at inner and outer circumferential sides of the cam groove, and a lubricant is sealed between the two sealing members. Valve train.