JPS6368710A - Cam device for internal combustion engine - Google Patents

Abstract

PURPOSE:To simplify a cam device by forming a normal rotation exhaust and a reverse rotation intake displacement part, and a normal rotation intake and a reverse rotation exhaust displacement part on the same peripheral surface of each of a primary and a secondary intake and exhaust cam to cause the switchover of a hydraulic circuit to make the switchover of each of said cams possible. CONSTITUTION:A cam shaft rotated by an engine is provided with an injection cam 5 driving a fuel injection pump 23, and a primary and a secondary intake and exhaust cam 17, 18 driving a primary and a secondary tappet valve devices 24, 25 at fixed intervals in its axial direction. Said primary cam 17 is formed with a normal rotation exhaust displacement part 19 and a reverse rotation intake displacement part 20, and said secondary cam 18 with a normal rotation intake displacement part 21 and a reverse rotation exhaust displacement part 22 on their same rolling surfaces. The tappet valve devices 24, 25 are connected through a directional control valve 26 to an intake valve device 27 and an exhaust valve device 28 which are hydraulically opened and closed, and said valve 26 is switched over to connect the primary tappet valve device 24 to said device 28 and the secondary tappet valve device 25 to said device 27 respectively at the normal rotation of the cam.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cam device in an internal combustion engine, particularly to a cam device for driving intake and exhaust valves.

[Prior Art] In a large internal combustion engine, when the output shaft is reversed, the internal combustion engine itself is reversed.

When the internal combustion engine itself is reversed, the camshaft on which the cams that drive the fuel injection pump, intake valves, and exhaust valves are installed also reverses.

Therefore, the cam device must have the shape and structure of each cam so that the injection pump, intake valve, and exhaust valve can be driven at the same timing during forward rotation and reverse rotation.

If we compare the movement of the driving pump plunger and the injection pump plunger of an internal combustion engine equipped with a valve train in which intake and exhaust valves are opened and closed by hydraulic pressure with the movement of the crankshaft and graph it, we can see that the rotation is normal. 11 (ω), and when the rotation is reversed, it becomes as shown in FIG. 11(b). As a cam device for causing such a plunger movement, there are those shown in FIGS. 7 to 1O.

In the figure, 1 is a shaft support, and a camshaft 2 is rotatably and slidably supported on the bearing support 1, and an intake cam 3, an exhaust cam 4, and an injection cam 5 are each fixed to this camshaft 2. There is. When the camshaft 2 rotates in the direction of arrow F, it is normal rotation, and when it rotates in the direction of arrow R, it is reverse rotation.

Tappets 6.7 for the intake cam 3, exhaust cam 4, and injection cam 5 each convert the movement of the cam into a plunger into linear motion.
．． 8 abut via rollers 9, 10.11. The intake cam 3 and the intake cam 4 are formed with a forward rotation cam portion 12.13 that operates the tappet 6.7° during forward rotation, and a reverse rotation cam portion 14.15 that operates the tappet during reverse rotation. It is connected to the cam part by a slope. During forward rotation, roller 9. The roller 9.10 is brought into contact with the forward rotation cam part 12.13, and the roller 9.10 is brought into contact with the reverse rotation cam part 14.15 during reverse rotation. This is done by moving in the direction. Incidentally, since the parts of the injection cam 5 that apply displacement to the tappet during normal rotation and reverse rotation are separated, the normal rotation cam part and the reverse rotation cam part can have the same shape. Also, the part that contributes to the operation of the cam or plunger is the diameter increasing part (tappet rising part).

[Problems to be Solved by the Invention] However, in the conventional example described above, the camshaft 2 must be moved in the axial direction each time the cam rotates forwardly or reversely, causing scratches on the rolling surface of the cam roller. Long-term operation will cause peeling due to fatigue.

The present invention was developed in view of the above-mentioned circumstances, and it is possible to prevent the roller rolling surface of the cam from peeling off without causing scratches on the rolling surface of the roller, so that it can be operated for a long period of time without any problems. The present invention aims to provide a cam device.

[Means for Solving the Problems] The present invention provides a forward rotation exhaust displacement portion on the same outer peripheral surface of the first suction/exhaust cam.
A reverse intake displacement section is formed, and a forward rotation intake displacement section and a reverse rotation exhaust displacement section are formed on the same outer peripheral surface of the second intake/exhaust cam, and the first and second valve operating devices and the intake valve device are respectively driven by both cams. , connected to the exhaust valve device by a hydraulic circuit having a switching valve,
- Switch the switching valve when the internal combustion engine rotates forward or reverse, and the first and second
This device is characterized in that the connection state of the valve train, intake valve device, and exhaust valve device can be switched.

[Function] During forward rotation, the first valve operating device driven by the normal rotation exhaust displacement portion of the first intake/exhaust cam operates the exhaust valve device, and the second valve device driven by the forward rotation intake displacement portion of the second intake/exhaust cam. The intake valve device is operated by the valve train, and when the reverse rotation occurs, the switching valve is switched, and the intake valve device is operated by the first valve train driven by the reverse intake displacement portion of the first intake/exhaust cam, and the intake valve device is operated by the reverse intake/exhaust valve of the second intake/exhaust cam. Operate the exhaust valve device at the displacement part.

[Implementation example] The present invention will be described in detail below with reference to the drawings.

First, the shape of the cam is made as shown in FIG. 1 (ω-(C)).

The injection cam 5 has the same shape as the conventional one, or a first suction/exhaust cam 17 and a second suction/exhaust cam 18 are prepared for intake valves and exhaust valves.

The first supply/exhaust cam 17 has a forward rotation exhaust displacement portion 19 on the same transfer surface.
and a reverse intake displacement section 20, and the second intake/exhaust cam 18 has a forward rotation intake displacement section 21 and a reverse rotation exhaust displacement section 2 on the same transfer surface.
form 2.

Next, the fuel injection pump 23 is driven by the injection cam 5, the first valve train 24 is driven by the first suction/exhaust cam 17, and the second valve train 25 is driven by the second suction/exhaust cam 18. The first valve operating device 24 and the second valve operating device 25 are connected to an intake valve device 27 and an exhaust valve device 28 via a switching valve 26 .

The first and second valve operating devices 24 and 25 each have a tappet 6
．． The hydraulic pressure is generated by the movement of the first and second
The valve devices 24 and 25 are configured so that the intake valve 29 and the exhaust valve 30 are opened and closed by this hydraulic pressure.

During normal rotation, the switching valve 26 connects the first valve operating device 24 and the exhaust valve device 28, and also connects the second valve operating device 25 and the air supply valve device 27.

By rotation of the camshaft 2 in the F direction, the injection cam 5, the first suction/exhaust cam 17, and the second suction/exhaust cam 18 drive the fuel injection pump 23, the first valve train 24, and the second valve train 25, respectively. The exhaust valve device 28 is driven by the oil pressure generated by the first valve device 24, and the intake valve device 27 is driven by the oil pressure generated by the second valve device 25.
The intake valve 29 opens and closes.

Then, the injection pump 23, the first valve train 24, and the second valve train 25 are operated at the timing shown in FIG. 11 (ω).

Next, when reversing the internal combustion engine, the switching valve 26 is switched in synchronization with the reversing operation lever, and the first valve operating device 24 and the intake valve device 27 are switched, and the second valve operating device 25 and the exhaust valve device are switched. 2
8, respectively.

Due to the reverse rotation of the camshaft, the first valve operating device 24 is driven by the reverse intake displacement portion 20 of the first intake/exhaust cam 17, and the second valve operating device 24 is driven by the reverse intake displacement portion 22 of the second intake/exhaust cam 18. Furthermore, the first valve operating device 24 drives the intake valve device 27 and the second valve operating device 25 drives the exhaust valve device 28 to drive the intake valve 29.
, opens and closes the exhaust valve 30.

Furthermore, the operation timing of the injection pump 23 changes due to the injection cam 5 being reversed.

Thus, the injection pump 23, the second valve train 25, and the first valve train 24 are driven at the timing shown in Fig. 11).

That is, in the forward/reverse conversion operation, there is no need to change the mechanical position of the tappet and the cam, and therefore no scratches occur on the cam.

Although the switching valve 26 described above is a solenoid valve, it may be a pilot type switching valve or may be operated manually.

Next, a valve train and a valve device driven by the above cam device will be illustrated.

In FIG. 3, the valve device 31 includes an intake/exhaust valve 33 that slides integrally with a piston 32, and the valve 33 is urged upward by compressed air enclosed in an accumulator 34. Further, an oil chamber 35 formed at the head of the piston 32 is configured to introduce pressure oil from a valve train 36, and the valve 33 is opened and closed by the action of the pressure oil.

Two valve opening barrels 38 and two valve closing barrels 39 are provided inside the casing 37 of the valve train 36 .
．． A valve-opening plunger 40 and a valve-closing plunger 41 are slidably fitted into the valve openings 39, respectively. Furthermore, sleeves 42 and 43 are rotatably fitted into both the barrels 40 and 41, respectively, and both sleeves 42 and 43 are connected to the plunger 4.
0.41 and are connected so that they can rotate together. Further, both plungers 40 and 41 are biased by a spring 45 so as to follow the tappet 44.

The insides of both barrels communicate with the oil chamber 35 via a communication path 46,
Further, a supply port 48 and a discharge port 49 communicating with the tank 47 are bored in the side walls of both barrels 38 and 39. A notch 50 that matches the supply port 48 is provided in the head of the valve opening plunger 40,
A discharge port 4 is provided in a narrow diameter portion 51 carved in the valve closing plunger 41.
9 is provided.

53 and 54 are valves.

With both plungers 40 and 41 in the lowest position, both barrels 38 and 39 are filled with oil, and plunger 40
．． 41 rises, the oil in the barrel is returned to the tank as surplus oil until the valve opening plunger 40 which is pushed out closes the supply port 48. When the supply port 48 is closed, hydraulic pressure is generated and the intake/exhaust valve 33 is closed. Pushed down. Valve closing plunger 41
When the narrow diameter part opens the discharge port 49, it is discharged into the tank through the discharge ports 49 in both barrels (the inside of the barrel and the narrow diameter part are communicated with each other by a groove 55). By opening the inside of the barrel, the oil pressure in the oil chamber 35 also decreases and the valve opens. That is,
The intake and exhaust valve 33 is opened by the upward movement of both plungers 40 and 41.
opens and closes.

Incidentally, by rotating the sleeves 42, 43, the timing at which the notches 50, 52 match with the supply port 48 and the discharge port 49 changes, and by adjusting the position of the sleeves 42, 43 in the rotational direction, the opening/closing operation of the valve can be adjusted.

Next, FIG. 4 shows an example of another valve operating system.

The tappet 44 is in contact with the plunger 58 via a pair of adjusting levers 56 and 57, one of which is in contact with a rod 60 that is slidably fitted into the casing 59. 61 can be opened and closed. Further, a rod 62 slidably fitted into the casing 59 contacts the other adjustment lever 57, and the rod 62 can contact the pressure adjustment piston 83.

When the plunger 58 rises, hydraulic pressure is generated, and along with the generation of the hydraulic pressure, the pressure adjustment piston 63 descends. While the pressure regulating piston 63 is descending, no large hydraulic pressure is generated, and therefore the intake and exhaust valves 33 do not open. When the tappet 44 rises, the rod 62 also rises, and together with the fall of the pressure adjusting piston 63, the two come into contact. From this point on, a sudden pressure is generated, and the intake and exhaust valves 33 are opened. Further, when the tappet 44 rises, the rod 60 pushes up the valve 61 to open it, and the pressure oil in the oil chamber 35 is discharged into the tank 47.

Thus, the intake and exhaust valves 33 are closed at this point.

In addition, 64.65 is an actuator, and the adjustment lever 56 is adjusted by moving its shaft 68.67 in and out.
．． The fulcrum of 57 is displaced, and both woods 80.82 and valve 61,
The contact timing of the pressure adjusting piston 83 changes, and the intake/exhaust valve 3
The opening/closing timing of 3 changes.

Furthermore, FIG. 5 shows an example of another valve operating system, and the third valve train shown in FIG.
The valve train shown in the figure has one plunger,
The opening/closing timing of the intake/exhaust valve 33 can be variably controlled within a limited range, and the one shown in FIG. 6 has substantially the same structure as the one shown in FIG. 5, but the opening/closing timing is fixed. Any of the valve train systems shown above is applicable to the present invention.

[Effects of the Invention] As described above, according to the present invention, forward and reverse rotations are possible simply by switching the hydraulic circuits between the valve train and the valve system, which simplifies the system significantly, and also allows the cam to slide against the tappet. Since there is no need to move the cam, there will be no scratches and the transfer surface of the cam will not be rough, extending the life of the cam.

[Brief explanation of the drawing]

Fig. 1 (ω<boc> is a diagram showing the shape of the cam used in the embodiment of the present invention, Fig. 2 is a conceptual diagram of the embodiment, and Fig. 3 is a valve train to which the embodiment can be applied. A sectional view showing an example of
FIGS. 4 to 6 are sectional views showing other valve operating devices, respectively;
Fig. 7 is a sectional view of a conventional cam device, and Fig. 8 is A of Fig. 7.
-A arrow view, Figure 9 is a B-B arrow view in Figure 7, Figure 10 is a C-C arrow view in Figure 7, and Figures 11 (a) and (b) are cam operation timings. FIG. 17 is a first intake/exhaust cam, 18 is a second intake/exhaust cam, 19 is a forward rotation exhaust displacement section, 20 is a reverse rotation intake displacement section, 21 is a forward rotation intake displacement section, 22 is a reverse rotation exhaust displacement section, and 24 is a first valve operating valve. device, 2
5 is a second valve operating device, 26 is a switching valve, 27 is an intake valve device,
28 indicates an exhaust valve device.

Claims (1)

[Claims] 1) A forward rotation exhaust displacement portion and a reverse rotation intake displacement portion are formed on the same outer peripheral surface of the first intake/exhaust cam, and a forward rotation intake displacement portion and a reverse rotation intake displacement portion are formed on the same outer peripheral surface of the second intake/exhaust cam, so that both cams a first and second valve operating device and an intake valve device each driven by the
The exhaust valve device is connected to the exhaust valve device through a hydraulic circuit having a switching valve, and the switching valve is switched when the internal combustion engine rotates in the forward or reverse direction, thereby switching the connection state between the first and second valve operating devices, the intake valve device, and the exhaust valve device. A cam device for an internal combustion engine characterized by: