JPH0472971B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for stopping the supply and exhaust valves of an internal combustion engine at a predetermined time, and in particular to a valve stopping device capable of cutting valve operating force between a cam and a camshaft in a valve train. .

A vehicle equipped with an internal combustion engine does not require a large amount of power when driving under a light load, such as when driving steadily on a flat road, driving at low speeds in a city area, or when revving. In such a case, the internal combustion engine only needs to ignite the minimum amount of fuel necessary to continue its operation, and both the amount of air supply and fuel can be kept low. In particular, in the case of a two-valve internal combustion engine that has two intake valves and two exhaust valves, at low output, one A system is known in which only the exhaust valve is operated, and all four valves are operated at high output. Furthermore, in the case of multi-cylinder engines,
As disclosed in the April 1957 issue, New Mechanism Commentary,
It is also known that the locker arms of some of the multiple cylinders are undone to keep the valves fully closed, stop output generation, and operate in cylinder deactivation during light loads to maintain constant drive. ing. All of these internal combustion engines can reduce wasteful fuel consumption and increase fuel efficiency, but they require a valve stop device to be installed in the valve train, and the valve train is more complex than a normal internal combustion engine. As a result, the mass of the drive section of the valve train increases, resulting in an increase in inertia.

SUMMARY OF THE INVENTION An object of the present invention is to provide a valve stop device that can suppress an increase in the mass of a valve train and eliminate malfunctions when switching between valve operation and valve stop.

The valve stop device according to the present invention includes a camshaft of a valve train of an internal combustion engine, and a plunger that is fitted into a guide hole formed in the camshaft and that can enter and retreat into a locking hole in an annular inner wall surface of the cam. , a hydraulic operating device for retracting the plunger from the locking hole when the valve is stopped, and the hydraulic operating device is characterized by having an on-off valve that can shut off the in-shaft oil passage and the hydraulic pressure source side.

The present invention will be described below with reference to the accompanying drawings. 1st
The figure shows a valve stop device 1 as an embodiment of the present invention. This valve stop device is installed in one cylinder of a multi-cylinder Ganlin engine (not shown) that performs normal operation and deactivation operation in a timely manner (only one cylinder is shown here, but it can be installed in the same way on multiple cylinders). be installed against the The valve train of this engine has a camshaft 2, which rotates at half the engine speed, pivoted on a cylinder head 3.
The air supply valve (not shown) is connected to the air supply valve (not shown) through each rocker arm 6 attached to the air supply valve rocker arm shaft 4 (see Fig. 2) and the exhaust valve rocker arm shaft 5, which are installed parallel to the camshaft 2. It has an overhead valve structure in which the exhaust valve 7 is operated. Here, the valve stop device 1 operates the air supply valve and the exhaust valve 7 in the same way during cylinder shutdown operation, and the structure is the same, so from now on, mainly the exhaust valve 7 will be used.
The side valve train system will be explained.

The camshaft 2 is attached to a mounting base 8 on the cylinder head 3 via a bearing 10 integral with the camshaft 2, and a camcap 9 is attached to the mounting base 8 on the cylinder head 3.
It can be installed by bolting. The cam cap 9 works together with a plurality of other cam caps (not shown) and the mounting base 8, and in addition to the cam shaft 2, the two rocker arm shafts 4,
5 (see Figure 2). Furthermore, an in-shaft oil passage 201 is formed in the center of the camshaft 2, and a hydraulic operating device OC is connected to this in-shaft oil passage 201. The hydraulic operating device OC is plunger 1, which will be described later.
9 is operated by sliding, and is formed by a hydraulic circuit. First, the cam cap 9, the mounting base 8, and the bearing part 10 work together to form an on-off valve V that connects the in-shaft oil passage 201 and the oil passage 11 that can communicate with the oil pressure source side in a manner that can be shut off. . This on-off valve V is
As shown in FIGS. 1 and 2, a part of the blocking part 103 on the entire outer peripheral surface of the bearing part 10 and a groove 101 excluding this part are provided. In addition, the blocking portion 103 in which no groove is formed is formed at the center of the lift portion a of the cam 16 (described later), that is, at the same rotational angular position as the direction of the center line l1 of the guide hole 18 (described later). The concave groove 101 and the shaft oil passage 201 are connected to the communication passage 10.
2, and the groove 101 or the blocking part 103
is the oil path 1 within the range of rotation angle θ every time the camshaft 2 rotates.
1 (see FIGS. 5 and 6). When the cam 16 and the camshaft 2 rotate as a single unit, the on-off valve V having such a configuration connects the in-shaft oil passage 201 to the oil passage 11 while the lift portion a of the cam presses the exhaust valve 7. That is, the hydraulic pressure source side is shut off, and the two are communicated at other times. The upper end of the oil passage 11 is connected to an oil control valve 13 via an oil pipe 12. The oil control valve 13 is a three-way solenoid valve that is operated by an output signal from a controller 14 made up of a microcomputer. During normal valve operation, the oil from the oil pump 15 is stored in an accumulator 151 serving as an oil reservoir, and is then flowed into the oil control valve 13. The oil is guided to the port 131, and when the valve is stopped, the oil is switched to be guided to the oil pipe 12 side through the operation port 132. In addition,
Reference numeral 133 indicates a drain port.

A pair of notched circular stopper pins 1 are attached to the camshaft 2.
7 are irremovably attached to each other, and the cam 16 is externally fitted onto the sliding wall surface 202 between them. Moreover, the camshaft 2 has its sliding wall surface 202 in sliding contact with the annular inner wall 161 of the cam 16, and this annular inner wall surface 161
A locking hole 163 in the shape of a truncated cone is formed in the central portion of the hole. Moreover, a guide hole 18 is formed in the sliding wall surface 202 so as to communicate with the locking hole 163 when the shutoff portion 103 of the above-mentioned on-off valve V faces the opening 111. As shown in FIG. 3, the guide hole 18 has a plunger 19 slidably fitted therein. The entire length of this plunger is slightly shorter than the length of the guide hole 18, and a hydraulic receiving surface 191 is provided in the center of the plunger.
is formed, and the partition wall 192 that forms this hydraulic pressure receiving surface
The lower side is formed into a cylindrical shape as a piston part 193, and the upper side is formed into a cylindrical shape as a protruding part 194. The guide hole 18 intersects the intrashaft oil passage 201 at the center of the camshaft at its center, and the oil pressure in the intrashaft oil passage is transferred to the oil pressure receiving surface 191 through a notch hole 195 formed in the side wall of the protrusion 194. Reportedly. The piston portion 193 is urged by the spring 21 in a direction away from the bottom wall 205 of the guide hole 18, thereby elastically pressing the truncated conical end of the protruding portion 194 to enter the locking hole 163. There is. Note that a narrow passage 204 is formed in the bottom wall 205, which allows oil and air to be released to the atmosphere through a relief groove 203 on the sliding wall surface 202.

Reference numeral 22 in FIG. 1 indicates a stopper post that restricts the range of the in-shaft oil passage 201.

The valve stop device 1 shown in FIG. 1 operates together with the engine. First, the controller 14 controls the engine speed, engine load, and
The gear position of the transmission, the on/off state of the clutch, etc. are detected, and an output signal is output to the oil control valve 13 only when it is operating under a light load or when the engine is racing. At other times, the output signal is stopped. That is, when the output signal is stopped, the oil control valve 13 is in the home position, and the pressure oil is supplied to the inflow port 131.
It only leads to the oil passage 11 and does not reach the oil passage 11 side. Therefore, the plunger 19 does not receive hydraulic pressure,
Receives only the elastic force of the spring 21, and its protruding portion 194
is inserted into the locking hole 163 when facing the locking hole 163.
As a result, the cam 16 rotates integrally with the camshaft 2, and the exhaust valve 7 is opened and closed in a normal state. Note that the air supply valves (not shown) also operate normally, and the cylinders equipped with these valves generate output. On the other hand, when the controller 14 issues an output signal, the oil control valve 13 is switched to guide pressure oil to the operating port 132 (indicated by a dashed line in FIG. 1), and this pressure oil reaches the oil passage 11. Oil road 1
The pressure oil of No. 1 is applied to the plunger 19 intermittently by an on-off valve V every rotation. That is, during the rotation angle θ where the groove 101 faces the opening 111, the pressure oil acts to retreat the plunger 19 into the guide hole 18, and lifts the cam 16 between the blocking portion 103 and the opening 111. During operation, the pressure oil is once cut off and the plunger 19 stops the retracting operation. Then, the plunger 19 continues its retreating operation when the valve is closed, during which the groove 101 again faces the opening 111. When the cam 16 enters a lift region in which the exhaust valve 7 is lifted, the on-off valve V cuts off the supply of pressure oil and temporarily stops the lift operation. Such an operation prevents the exhaust valve 7 from being left open or from being suddenly closed. That is, once pressure oil is applied to the plunger 19, the plunger may stop retracting in an incomplete state as shown in FIG. In this case, the plunger 19 is subjected to the pressing force F caused by the pressure oil and the frictional force that the protruding portion 194 receives from the wall surface of the locking hole 163, but component 1 of this frictional force is greater than the pressing force F. in a state. However, when the cam 16 rotates, near the maximum lift position a1 of the cam, a reaction force P based on the force that the cam 16 is receiving from a valve spring (not shown) is generated.
The direction of is reversed, and the frictional force temporarily disappears,
At that time, if the hydraulic pressure is working, the plunger 19 completes its retreat. If this operation occurs, the rocker arm 6 will be in the vicinity of the maximum lift position a1 of the cam 16.
(see Fig. 7), and the exhaust valve 7 remains open, or the exhaust valve 7 is closed to the cam 1.
The idling of valve 6 results in a sudden closing operation, but the above-mentioned disadvantage is prevented by the action of on-off valve V.

After the plunger 19 retreats, the camshaft 2 idles relative to the cam 16, and the exhaust valve 7 remains fully closed. Similarly, since the air supply valve (not shown) is also maintained in a fully closed state, the cylinder with both valves closed enters a cylinder deactivation operation in which output generation is stopped. Note that when the controller 14 stops the output again, the plunger 19 receives only the elastic force of the spring 21 again, and its protrusion 194 engages with the locking hole 16 of the cam.
3, the cam 16 and the camshaft 2 rotate integrally, and the cylinder again enters normal operation capable of generating output.

In this manner, by operating the valve stop device 1 at a predetermined time, the cylinder to which the valve stop device 1 is attached can perform normal operation and cylinder-stop operation, and fuel consumption can be kept low. In particular, this valve stop device 1
The on-off valve V, which operates in synchronization with the cam 16, shuts off the pressure oil applied to the plunger 19 every time the cam lifts, thereby stopping the retreat operation of the plunger 19. Therefore, it is possible to prevent the exhaust valve 7 and the air supply valve (not shown) from being left open or causing a sudden valve closing operation via the rocker arm 6 near the maximum lift position a1 of the cam. Furthermore,
The valve stop device 1 does not increase the mass of the swinging end like the rocker arm 6, but only adds a plunger 19 within the rotating camshaft 2, and the mass of the valve system is smaller than that of the conventional device. It has the advantage of being easy to operate at high speeds. Moreover, the structure, especially the synchronization structure of the on-off valve V with the cam, is simplified, costs can be kept low, and reliability is improved.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a main part of a valve stop device as an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line X-X in FIG. 1, and FIG. 3 is a cross-sectional view taken along the Y-Y line in FIG. , FIG. 4 is an enlarged view showing the state of engagement between the plunger and the locking hole 163, FIGS. 5 and 6 are explanatory diagrams of each operating state when the cam and the camshaft rotate together, and FIG. 7 1A and 1B respectively show explanatory diagrams of the operating state when the cam and the camshaft are separated. 1... Valve stop device, 2... Camshaft, 16... Cam, 18... Guide hole, 19... Plunger, 1
61... Annular inner wall surface, 163... Locking hole, 191
...Hydraulic pressure receiving surface, 201...In-shaft oil path, OC...Hydraulic operating device, V...Opening/closing valve.

Claims (1)

[Claims] 1. A cam shaft in a valve train of an internal combustion engine, a cam that is slidably fitted onto the cam shaft and has an annular inner wall surface, and a cam that is fitted into a guide hole formed in the cam shaft; and a plunger that can enter and retreat into a locking hole formed in an annular inner wall surface, and a hydraulic pressure receiving surface formed in the center of the plunger to receive hydraulic pressure from an in-shaft oil passage formed in the camshaft when the valve is stopped. In addition to
A hydraulic operating device for retracting a plunger from a locking hole, the hydraulic operating device comprising an on-off valve capable of shutting off an in-shaft oil passage and a hydraulic pressure source side.