JP2580994B2 - Valve train for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve train for an internal combustion engine for controlling the operation of an intake valve and an exhaust valve provided in an automobile engine or the like.

[0002]

2. Description of the Related Art Generally, in opening and closing control of an intake valve and an exhaust valve in an automobile engine, an opening and closing timing is set according to an operating state obtained from an engine speed, an accelerator pedal depression amount, and the like. In such a valve train, there has been proposed a valve train in which fuel consumption is reduced at low speeds and the profile of a cam is changed at high speeds so that intake and exhaust can be performed efficiently at high speeds. . This is performed by changing the opening / closing timing of the intake valve and the exhaust valve, the lift amount, the opening period, and the like at a low speed or a high speed.

That is, in an automobile engine, a high-speed cam and a low-speed cam are provided on a cam shaft, and the high-speed cam has a cam profile capable of obtaining a valve opening / closing timing corresponding to a high-speed operation. The cam has a cam profile capable of obtaining a valve opening / closing timing corresponding to a low-speed operation. By selectively using the high-speed cam or the low-speed cam according to the operating state during the operation of the engine, it is possible to obtain the optimal opening / closing timing of the intake valve and the exhaust valve. I have.

[0004] In such an automobile engine, during idle operation or low-load operation, for example, in the case of a four-cylinder engine, a cylinder stop mechanism for stopping two cylinders to reduce fuel consumption has been conventionally used. Proposed. That is,
In the valve operating device, the piston is operated at the time of idling operation or low-load operation, but the operation of the intake valve and the exhaust valve is stopped so as not to supply fuel.

The cylinder closing mechanism for stopping the operation of the intake valve and the exhaust valve is generally operated by providing a rocker arm with a switching mechanism and controlling the switching mechanism by hydraulic pressure. In this case, hydraulic pressure is supplied from the main oil pump of the engine to the switching mechanism via an oil passage. However, in order to operate the switching mechanism, a high hydraulic pressure cannot be obtained from the main oil pump of the engine alone because the operating hydraulic pressure alone is insufficient. That is, as shown in FIG. 13, there is a minimum required switching hydraulic pressure for operating the switching mechanism, and the operating hydraulic pressure from the main oil pump of the engine is lower than the required switching hydraulic pressure. Therefore, by providing an assist oil pump separately from the main oil pump of the engine, the operating oil pressure of the switching mechanism is set to be higher than the operation required oil pressure.

FIG. 14 is a plan view of a cylinder head showing a conventional valve train of an engine having a cylinder rest mechanism, and FIG. 15 shows a hydraulic path of the valve train.

As shown in FIGS. 14 and 15, a camshaft 202 is rotatably mounted at the center of the cylinder head 201, and a cam (not shown) is integrally formed at a predetermined position. A pair of rocker shafts 203 are mounted on the cylinder head 201 so as to be rotatable in parallel with the camshaft 202. A base end of a rocker arm 206 having a rocker arm 204 and a switching mechanism 205 is mounted on each rocker shaft 203, and a swinging end of each rocker arm 204, 206 faces an upper end of an intake or exhaust valve 207. ing. Further, an oil pump 208, an accumulator 209, and an oil control valve 210 are mounted at an end of the cylinder head 201. The oil pump 208 can be driven by a drive cam 211 attached to one end of the cam shaft 202, and the oil control valve 210 can be operated by a control signal of a control unit 212.

[0008] When the camshaft 202 rotates, the rocker arm 204 and the rocker arm 206 swing by the cam to drive the intake and exhaust valves 207. Then, at the time of idling operation or low load operation of the engine, the operation is performed with two of the four cylinders stopped. That is, the oil pump 208 is driven by the drive cam 211 of the camshaft 202, and the hydraulic pressure is stored in the accumulator 209. On the other hand, the control unit 212 determines the operating state of the engine based on signals from various sensors, sends a control signal to the oil control valve 210, and switches the control signal. Then, the hydraulic pressure is sent to the switching mechanism 205 of the rocker arm 206, and the driving of the corresponding intake and exhaust valves 207 is stopped. Accordingly, the engine operates only by driving the intake and exhaust valves 207 corresponding to the rocker arm 204.

[0009]

In the above-described conventional valve train of an engine, during rocking operation or low load operation, some rocker arms 206 are switched to stop two of the four cylinders. The mechanism 205 is mounted. Therefore, the oil pump 208 or the accumulator 20
9 and the like are required, and these must be mounted on the cylinder head 201. Conventionally, as described above, the cylinder head 201 is provided above one end, but this causes a part of the engine to protrude upward. In addition, the cylinder head cover that covers the upper part of the cylinder head 201 must also have a shape that protrudes upward in accordance with that, and the height of the engine increases.
This not only causes an increase in size, but also makes the layout when mounted on a vehicle difficult.

An object of the present invention is to solve such a problem, and an object of the present invention is to provide a valve train for an internal combustion engine in which the size of the internal combustion engine is reduced.

[0011]

SUMMARY OF THE INVENTION The above valve operating system for an internal combustion engine of the present invention for achieving the objects of the 2 two rows of cylinders in each row are arranged at a predetermined angle to each other with respect to the crankshaft DOHC with one camshaft
In a multi-cylinder internal combustion engine, a pair of camshafts provided with a low-speed cam and a high-speed cam and offset in the axial direction with respect to each of the two rows of cylinders and arranged two in each row, A main rocker arm whose end is supported by the engine body and whose swinging end faces the upper end of the intake or exhaust valve and which engages with either the low-speed cam or the high-speed cam; A sub rocker arm that is supported and engages with the other of the low speed cam and the high speed cam, a connection switching mechanism that couples and disengages the main rocker arm and the sub rocker arm,
A hydraulic control device for controlling the operation of the connection switching mechanism, wherein the camshafts are offset in the axial direction of the camshaft between the two camshafts in each row, and A hydraulic control device is provided.

[0012]

The two rows of cylinders are arranged at a predetermined angle with respect to the crankshaft, and two cylinders are provided in each row.
In a DOHC multi-cylinder internal combustion engine having a camshaft, a hydraulic control device for controlling the operation of a connection switching mechanism is disposed in a space formed by offsetting each camshaft between two camshafts in each row . This saves space and makes the device compact, and facilitates layout when mounted on a vehicle.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a plan view of a cylinder head showing a valve train of an internal combustion engine according to one embodiment of the present invention, and FIG.
-A cross section, FIG. 3 shows BB cross section of FIG. 1, and FIG.
C section, FIG. 5 is a plane view of the valve train with a cylinder rest mechanism, FIG. 6 is a DD section of FIG. 5, FIG. 7 is a section EE of FIG. 5, FIG. FIG. 9 is a cross section showing a switching mechanism of the valve operating device, FIG. 10 is a hydraulic path of the valve operating device, FIG. 11 is an explanatory view of the operation of the switching mechanism, and FIG.

In the internal combustion engine of this embodiment, two rows of cylinders are arranged in a V-shape at a predetermined angle with respect to the crankshaft, and each cylinder has two camshafts. A DOHC) V-type six-cylinder engine is provided with two valves for intake and two valves for exhaust.

As shown in FIGS. 1 and 2, a crankshaft 2 is rotatably supported on a cylinder block 1.
Two rows of three cylinders 3 each having a predetermined angle with respect to the crankshaft 2 are formed in a V-shape. In this case, each of the two rows of cylinders 3 is formed so as to be displaced in the axial direction of the crankshaft 2. A piston 5 is connected to the crankshaft 2 via a connecting rod 4, and the piston 5 is movably fitted in each cylinder 3. Valve operating mechanisms 6 and 7 are provided above the cylinders 3 in two rows, respectively. Since the valve mechanisms 6 and 7 have substantially the same configuration, only one of them will be described below. And
As described above, the cylinders 3 are inclined with respect to the crankshaft 2 at a predetermined angle, but are described in an upright state in the drawing for easy understanding.

As shown in FIGS. 2 and 5 to 7, the cylinder head 11 has a pair of intake camshafts 12 and exhaust cams located above the cylinder 3 and parallel to each other along the longitudinal direction. A shaft 13 is provided, and a low-speed cam 14 having a small lift amount and a high-speed cam 15 having a large lift amount are integrally formed for each cylinder. The pair of camshafts 12 and 13 are connected to the upper portion of the camshaft housing 16 and the plurality of camcaps 1.
By being fixed to the upper part of the cylinder head 11 by bolts 18 and 19 while being held by the cylinder 7, the cylinder head 11 is rotatably supported by the cylinder head 11.

The cylinder head 11 has a pair of intake rocker shafts 21 and a pair of exhaust rocker shafts 22 that are parallel to each other along the longitudinal direction thereof and are parallel to the pair of camshafts 12 and 13, respectively. It is arranged for each. The pair of rocker shafts 21 and 22 are held between the lower portion of the camshaft housing 16 and the plurality of rocker shaft caps 23 by bolts 19 and 24 and the cylinder head 11.
Is rotatably supported by the cylinder head 11 by being fixed to the lower part of the cylinder head. Note that a cylinder head cover 25 is fixed to an upper portion of the cylinder head 11.

Each of the rocker shafts 21 and 22 has a valve operating device that can be switched between a valve opening / closing timing for high-speed operation and a valve opening / closing timing for low-speed operation. And a valve train that can be closed during low load operation. That is, as shown in FIG. 1, the valve operating device 31 of the upper two cylinders among the six cylinders has a cylinder closing mechanism, and the valve operating device 32 of the lower four cylinders does not have the cylinder stopping mechanism.

Here, the valve train 31 with a cylinder rest mechanism will be described. As shown in FIG. 8, a main rocker arm 33 having a T-shape in plan view is mounted on the exhaust rocker shaft 22, and low-speed rocker arms 34 and high-speed rocker arms 35 are mounted on both sides thereof as sub rocker arms. . The main rocker arm 33 has a base end whose rocker shaft 2
2, and an adjusting screw 36 is attached to an oscillating end thereof by an adjusting nut 37.
The lower end of the adjusting screw 36 is in contact with the upper end of an exhaust valve 80 described later.

On the other hand, the low-speed rocker arm 34 has its base end pivotally mounted on the rocker shaft 22 and is rotatably supported. A roller bearing 38 is attached to its swinging end. Cam 14 can be engaged. Similarly, the base end of the high-speed rocker arm 35 is pivotally connected to the rocker shaft 22 and is rotatably supported. A roller bearing 39 is attached to the swinging end of the rocker arm 35. Cam 15 can be engaged.

Further, as shown in FIG. 7, the low-speed rocker arm 34 and the high-speed rocker arm 35 are integrally provided with arm portions 40 and 41, respectively, on the side opposite to the swinging end where the roller bearings 38 and 39 are mounted. The lost motions 42 and 43 act on the arm portions 40 and 41. The lost motions 42 and 43 include a cylinder 44 and a plunger 45 fixed to the cam cap 17,
The plunger 45 is constituted by a compression spring 46.
7 presses the arm portions 40 and 41 to urge the rocker arms 34 and 35 shown on the left side in FIG. 7 in the clockwise direction and the rocker arms 34 and 35 shown on the right side in the counterclockwise direction. ing.

Accordingly, the rocker arm 34 for low speed is normally used.
And the high-speed rocker arm 35 has lost motion 4
The roller bearings 38 and 39 are in contact with the outer peripheral surfaces of the low speed cam 14 and the high speed cam 15 of the camshaft 13 by the camshafts 2 and 43. When the camshaft 13 rotates, the cams 14 and 15 act. Thus, the low-speed rocker arm 34 and the high-speed rocker arm 35 can be swung.

As shown in FIG. 9, the low speed rocker arm 34 and the high speed rocker arm 35 can be rotated integrally with the rocker shaft 22 by the switching mechanism 50. A through-hole 51 is formed in the rocker shaft 22 at a position corresponding to the low-speed rocker arm 34 along the radial direction. A lock pin 52 is movably mounted in the through-hole 51, and a spring seat 53 is provided. It is urged in one direction by a supported compression spring 54. On the other hand, an engagement hole 55 is formed in the low-speed rocker arm 34 at a position corresponding to the through hole 51 of the rocker shaft 22, and a lock pin 52 urged by a compression spring 54 is engaged with the engagement hole 55. ing. A hydraulic passage 56 communicating with the through hole 51 is formed in the rocker shaft 22 along the axial direction, and the lock pin 52 communicates with the hydraulic passage 56 and has an opening on the side engaged with the engaging hole 55. An oil passage 57 is formed.

A through-hole 58 is formed in the rocker shaft 22 at a position corresponding to the high-speed rocker arm 35 along the radial direction. A lock pin 59 is movably mounted in the through-hole 58. , Compression spring 6
It is biased in one direction by 0. On the other hand, the high-speed rocker arm 35 has a through hole 5 of the rocker shaft 22.
An engagement hole 61 is formed at a position corresponding to 8, and the lock pin 59 is pulled out of the engagement hole 59 by the compression spring 60. A hydraulic passage 62 communicating with the through hole 58 is formed in the rocker shaft 22 along the axial direction, and an oil passage 63 communicating with the end of the through hole 58 on the opposite side to the engaging hole 59 is formed. Have been.

Normally, as shown in FIG. 11A, the low-speed rocker arm 34 is engaged with the lock pin 52 urged by the compression spring 54 into the engagement hole 55, so that the rocker shaft 22 can be rotated. And can rotate together with the main rocker arm 33 via the rocker shaft 22. On the other hand, in the high-speed rocker arm 35, the lock pin 59 urged by the compression spring 60 comes out of the engagement hole 61, and the engagement with the rocker shaft 22 is released, so that the locker arm 35 does not rotate integrally with the rocker shaft 22. It has become. Therefore, the low-speed cam 14 and the high-speed cam 15 swing the low-speed rocker arm 34 and the high-speed rocker arm 35, but only the transmitted driving force of the low-speed rocker arm 34 is transmitted to the main rocker via the rocker shaft 22. The main rocker arm 33 is transmitted to the arm 33 and can swing.

When hydraulic pressure is supplied to the hydraulic passages 56 and 62 of the rocker shaft 22, as shown in FIG. 11 (b), in the low-speed rocker arm 34, the pressure oil flows through the oil passage 57. It flows toward the engagement hole 55 of the through hole 51, and pulls out the lock pin 52 from the engagement hole 55 against the urging force of the compression spring 54. Then, the engagement between the low-speed rocker arm 34 and the rocker shaft 22 is released, and the low-speed rocker arm 34 does not rotate integrally. On the other hand, in the high-speed rocker arm 35, the pressure oil flows through the oil passage 63 to the opposite side of the engagement hole 61 of the through hole 58, and the lock pin 59 resists the urging force of the compression spring 54. The engaging hole 61 is engaged. Then, the high-speed rocker arm 35 and the rocker shaft 22 are engaged, and both can rotate integrally. Accordingly, the low-speed cam 14 and the high-speed cam 15 swing the low-speed rocker arm 34 and the high-speed rocker arm 35, but only the transmitted driving force of the high-speed rocker arm 35 is transmitted to the main rocker via the rocker shaft 22. The main rocker arm 33 is transmitted to the arm 33 and can swing.

The hydraulic passage 5 of the rocker shaft 22
When the hydraulic pressure is supplied only to the lock pin 6, as shown in FIG. 11C, in the low-speed rocker arm 34, the pressure oil flows to the engagement hole 55 side of the through hole 51, and the lock pin 52 is inserted into the engagement hole 55. Then, the low-speed rocker arm 34 and the rocker shaft 22 are disengaged from each other so that they do not rotate together. On the other hand, in the high-speed rocker arm 35, the lock pin 59 comes out of the engagement hole 61 by the compression spring 60 and the engagement with the rocker shaft 22 is released, and the two do not rotate integrally. Therefore, the low speed cam 14 and the high speed cam 15 swing the low speed rocker arm 34 and the high speed rocker arm 35, but the driving force is not transmitted to the rocker shaft 22 and the main rocker arm 33 does not operate. The cylinder can be brought into the closed state.

Further, in the valve train 32 without the cylinder rest mechanism, as shown in FIG.
Has a T-shaped rocker arm 64 for low speed.
And a high-speed rocker arm 65 is mounted. The base end of the low-speed rocker arm 64 is the rocker shaft 2.
2 are integrally consolidated. A roller bearing 66 is attached to the swinging end of the low-speed rocker arm 64 so that the low-speed cam 14 can be engaged.
The lower end of the adjustment screw 67 is in contact with the upper end of an exhaust valve 80 described later.

On the other hand, the base end of the high-speed rocker arm 65 is rotatably supported by being pivotally mounted on the rocker shaft 22, and a roller bearing 69 is attached to the swing end thereof. High-speed cam 15
Can be engaged. An arm 70 is integrally formed on the high-speed rocker arm 65 on the side opposite to the swinging end on which the roller bearing 69 is mounted, and a lost motion 71 acts on this arm 70, and the high-speed rocker arm 65 65 is urged in one direction. Further, the high-speed rocker arm 65 can be rotated integrally with the rocker shaft 22 by the switching mechanism 72. That is, a through-hole 73 is formed in the rocker shaft 22 at a position corresponding to the high-speed rocker arm 65, a lock pin 74 is movably mounted, and is urged and supported by a compression spring 75. On the other hand, an engagement hole 76 is formed in the high-speed rocker arm 65, and the lock pin 74 is pulled out of the engagement hole 76 by a compression spring 75. And rocker shaft 2
2, a hydraulic passage 77 communicating with the through hole 73 is formed along the axial direction, and an oil passage 78 communicating with an end of the through hole 73 opposite to the engaging hole 76 is formed.

Usually, the high-speed rocker arm 65
The lock pin 74 comes out of the engagement hole 76 by the compression spring 75, and the engagement with the rocker shaft 22 is released, so that the lock pin 74 does not rotate integrally with the rocker shaft 22. Therefore, the low-speed cam 14 and the high-speed cam 15 swing the low-speed rocker arm 64 and the high-speed rocker arm 65, but the driving force of the low-speed cam 14 is transmitted to an exhaust valve 80 described later, and the exhaust valve 80 Can be rocked. When hydraulic pressure is supplied to the hydraulic passage 77 of the rocker shaft 22, in the high-speed rocker arm 65, the pressurized oil flows through the oil passage 78 to the opposite side of the through-hole 73 from the engagement hole 76 and locks. The pin 59 is engaged with the engagement hole 76. Then, the rocker arm 65 for high speed and the rocker shaft 2
2 are engaged, and can be rotated integrally with the rocker shaft 22. Therefore, the high-speed cam 15 swings the high-speed rocker arm 35, and the driving force is transmitted to the exhaust valve 80 via the rocker shaft 22 and the low-speed rocker arm 64 to swing the exhaust valve 80. I can do it.

In the above description of the valve trains 31 and 32, only the exhaust side has been described. However, the intake side has the same structure, and each camshaft is adjusted in accordance with the opening and closing timing of the intake and exhaust valves. Only the formation positions of the cams 12 and 13 in the circumferential direction are different.

As shown in FIG. 7, the intake valve 79 and the exhaust valve 80 are movably mounted on the cylinder head 11, and the intake port 83 and the exhaust port 84 are closed by valve springs 81 and 82. Accordingly, by driving the upper ends of the intake valve 79 and the exhaust valve 80 by driving the above-mentioned main rocker arm 33 (low-speed rocker arm 64), the intake port 83 is formed.
The exhaust port 84 can be opened and closed to communicate with the combustion chamber 85.

As shown in FIGS. 1, 3 and 4, in the cylinder head 11, the camshafts 12 and 13 are also axially offset in correspondence with the left and right offset rows of the cylinders 3, respectively. As a result, a space is formed at the axial end of each of the camshafts 12 and 13. Therefore, in this embodiment, a hydraulic control device 86 for operating the switching mechanisms 50 and 72 of the valve gears 31 and 32 is provided in this space. The hydraulic control device 86 includes an oil pump 87, an accumulator 88, an oil control valve 89 for high-speed switching, and an oil control valve 90 for cylinder switching. The hydraulic control devices 86 provided at the axial ends of the left and right camshafts 12 and 13 have substantially the same structure, and only one of them will be described.

The oil pump 87 and the accumulator 88 are located between the intake camshaft 12 and the exhaust camshaft 13, and are arranged vertically one above the other, and their axial centers are horizontal. ing. That is, the oil pump 87 is provided on the side of the cam cap housing 16 and the cam cap 17 at the rearmost part of the cylinder head 11.
The cylinder 91 is horizontally movable and urged and supported by a compression spring 92, and is fixed by a bolt 94 via a cover 93. A plunger 96 acts on a cylinder 91 of the oil pump 87 via a compression spring 95, and the plunger 96 can be driven by an oil pump cam 97 formed integrally with one end of the intake camshaft 12. It has become.

A cylinder 98 of an accumulator 88 is horizontally movable at the lower side of the cam cap housing 16 and the cam cap 17 and is urged and supported by a compression spring 99. And is fixed by bolts 94. The diameter of the cylinder 91 of the oil pump 87 and the diameter of the cylinder 98 of the accumulator 88 are the same and can be shared.
The high-speed switching oil control valve 89 and the cylinder-stop switching oil control valve 90 are mounted on the cylinder head 11.

As shown in FIGS. 3, 4 and 10, the high-speed switching oil control valve 89 is directly connected to a main oil pump (not shown) of the engine via an oil passage 100, and has a hydraulic pressure via an oil passage 101. It is connected to a passage 62. Further, the cylinder-stop switching oil control valve 90 is connected to the accumulator 88, the oil pump 87, and the main oil pump via an oil passage 102, and to the hydraulic passage 56 via an oil passage 103.
Further, each of the oil control valves 89, 90 can be operated by a control signal of the engine control unit 104.

The switching mechanism 72 of the valve train 32 can be operated by a hydraulic control device 86 in the same manner as the valve train 31. An oil passage (not shown) is provided in the hydraulic passage 77 of the rocker shaft 22. The oil control valve 89 is connected via the. As shown in FIG. 3, a hollow plug tube 105 is provided upright for each cylinder in the cylinder head 11, and an ignition plug 106 is provided inside each plug tube 105.
Is mounted, and the front end faces each combustion chamber 85.

The operation of the V-type six-cylinder engine of this embodiment will be described below. Engine control unit 1
04 detects the operating state of the engine based on the detection results of various sensors, and selects a cam profile suitable for the running state of the engine if the engine is running at a low speed. In this case, the engine control unit 104 outputs a control signal to each of the oil control valves 89 and 90, and
9. Close 90. Then, each of the hydraulic passages 56, 62, 7
7 is not supplied with pressure oil, and the valve gear 31 is configured as shown in FIG.
As shown in FIG. 7, the lock pin 52 makes the low-speed rocker arm 34 and the rocker shaft 22 integral with each other, and the engagement between the high-speed rocker arm 35 and the rocker shaft 22 is released. Accordingly, when the camshafts 12 and 13 rotate, the low-speed rocker arm 34 swings by the low-speed cam 14, and the driving force is transmitted to the main rocker arm 33 via the rocker shaft 22, and the main rocker arm 33 is moved. Swing, a pair of adjusting screws 36 at the swing end are connected to the intake valve 79 and the exhaust valve 8.
Drive 0. On the other hand, as shown in FIG. 12, the valve gear 32 includes a high-speed rocker arm 65 and a rocker shaft 2.
When the cam shafts 12 and 13 are rotated and the camshafts 12 and 13 rotate, the low-speed cam 14 swings the low-speed rocker arm 64, and a pair of adjustment screws 6 at the swing end.
7 drives the intake valve 79 and the exhaust valve 80. Thus, the intake valve 79 and the exhaust valve 80 are driven at the valve opening / closing timing corresponding to the low-speed operation, and the engine is operated at a low speed.

When the engine control unit 104 detects the high-speed running state of the engine, the engine control unit 104
A control signal is output to 9, 90, and each valve 89, 90 is opened. Then, pressure oil is supplied to each of the hydraulic passages 56, 62, and 77, and when the engine is running at a high speed, the valve train 31 is operated.
As shown in FIG. 11B, the lock pin 52 is pulled out of the engagement hole 55 by the pressure oil, and the engagement between the low-speed rocker arm 34 and the rocker shaft 22 is released. Further, the lock pin 59 is engaged with the engagement hole 61 so that the high-speed rocker arm 35 and the rocker shaft 22 are integrated. Accordingly, the high-speed rocker arm 35 swings by the high-speed cam 15, and further the main rocker arm 33.
Swings to drive the intake valve 79 and the exhaust valve 80. On the other hand, in the valve gear 32, the lock pin 59 is engaged with the engagement hole 76 by the supply pressure oil, and the high-speed rocker arm 65 and the rocker shaft 22 are integrated. Therefore, the high-speed rocker arm 3 is moved by the high-speed cam 15.
5 swings to drive the intake valve 79 and the exhaust valve 80. Thus, the intake valve 79 and the exhaust valve 8
0 drives at the valve opening / closing timing corresponding to high-speed operation, and the engine is operated at high speed.

Then, the engine control unit 1
When the engine 04 detects an idling operation state or a low-load running state of the engine, two of the four cylinders are stopped to reduce fuel consumption. That is, the engine control unit 104
Outputs a control signal to each of the oil control valves 89 and 90, and opens only the valve 90. Then, the hydraulic passage 5
As shown in FIG. 11C, the valve gear 31 is disengaged from the low-speed rocker arm 34 and the rocker shaft 22. Therefore, the low speed cam 1
The driving force of the cam 4 and the high-speed cam 15 is not transmitted to the main rocker arm 33, and the valve train 31 is not operated and the cylinder is in a closed state. On the other hand, in the valve operating device 32, the low-speed rocker arm 64 swings by the low-speed cam 14 to drive the intake valve 79 and the exhaust valve 80. In this way, the engine is operated by driving only the intake valve 79 and the exhaust valve 80 of the valve train 32.

As described above, in the engine valve operating apparatus of the present embodiment, the hydraulic control apparatus 86 for operating the switching mechanisms 50 and 72 of the valve operating apparatuses 31 and 32 includes the oil pump 87, the accumulator 88, and the respective oil control units. Valve 8
9, 90, etc., and this hydraulic control device 86 is provided in the space at the axial end of each of the camshafts 12, 13 arranged corresponding to the left and right offset rows of cylinders 3, and An oil pump 87 and an accumulator 88 are provided between the intake camshaft 12 and the exhaust camshaft 13.
Are arranged vertically, the oil pump 87 and the accumulator 88 can be arranged efficiently, and the cylinder head 1
The layout of 1 is compact, so that a part of the engine does not protrude upward and the height does not increase.

In the above-described embodiment, the internal combustion engine is described as a V-type six-cylinder engine. However, a V-type multi-cylinder internal combustion engine in which two rows of cylinders are arranged at a predetermined angle with respect to a crankshaft. It is good if it is. Further, the hydraulic control device 86 is provided inside the cylinder head 11, but may be provided outside.

[0044]

Effect of the Invention] According to the valve operating system for an internal combustion engine of the present invention as described in detail by way of Examples, two rows of cylinders is disposed at a predetermined angle to each other with respect to the crankshaft Has two camshafts in each row
In a DOHC multi-cylinder internal combustion engine, a pair of low-speed cams and high-speed cams are mounted, and a pair of camshafts are provided offset to each other in the axial direction corresponding to each of the two rows of cylinders. Alternatively, a main rocker arm facing the upper end of the exhaust valve and engaging either the low speed cam or the high speed cam and a sub rocker arm engaging the other of the low speed cam and the high speed cam are provided. And a hydraulic control device for controlling the operation of the coupling and disengagement mechanism for coupling and disengagement between the camshaft and the sub rocker arm. Since this hydraulic control device is arranged in the space formed by offsetting, part of the internal combustion engine may protrude upward or its height may increase. Or Tsu, it is possible to efficiently arrange the hydraulic control device without changing the overall size of the internal combustion engine, it is possible to reduce the size of the internal combustion engine is the layout of the cylinder head is compact.

[Brief description of the drawings]

FIG. 1 is a plan view of a cylinder head showing a valve train of an internal combustion engine according to one embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 1;

FIG. 4 is a sectional view taken along the line CC of FIG. 3;

FIG. 5 is a plan view of a valve train with a cylinder rest mechanism.

FIG. 6 is a sectional view taken along line DD of FIG. 5;

FIG. 7 is a sectional view taken along line EE of FIG. 5;

FIG. 8 is an exploded perspective view of the valve train.

FIG. 9 is a cross-sectional view illustrating a switching mechanism of the valve train.

FIG. 10 is a hydraulic path diagram of the valve train.

FIG. 11 is a diagram illustrating the operation of the switching mechanism.

FIG. 12 is a cross-sectional view of a valve train without a cylinder rest mechanism.

FIG. 13 is a graph showing the operating oil pressure when the cylinder of the internal combustion engine is closed.

FIG. 14 is a plan view of a cylinder head representing a valve train of an engine having a conventional cylinder rest mechanism.

FIG. 15 is a hydraulic path diagram of a conventional valve train.

[Explanation of symbols]

2 Crankshaft 3 Cylinder 11 Cylinder head 12, 13 Camshaft 14 Low speed cam 15 High speed cam 21, 22 Rocker shaft 31, 32 Valve train 33 Main rocker arm 34, 64 Low speed rocker arm (sub rocker arm) 35, 65 High-speed rocker arm (sub rocker arm) 42, 43, 71 Lost motion 50, 72 Switching mechanism 51, 58, 73 Through hole 52, 59, 74 Lock pin 55, 61, 76 Engagement hole 56, 62, 77 Hydraulic pressure Passageway 79 Intake valve 80 Exhaust valve 86 Hydraulic controller 87 Oil pump 88 Accumulator 89 High-speed switching oil control valve 90 Cylinder switching oil control valve 104 Engine control unit

Claims (1)

(57) [Claims] 1. Two rows of cylinders are disposed at a predetermined angle with respect to a crankshaft, and two cylinders are provided in each row.
In a DOHC multi-cylinder internal combustion engine having a camshaft , a low-speed cam and a high-speed cam are mounted and axially offset from each other corresponding to each of the two rows of cylinders.
A pair of camshafts , two in each row, and one of the low-speed cam and the high-speed cam whose base end is supported by the engine body and whose swinging end faces the upper end of the intake or exhaust valve. A main rocker arm, one of which engages; a sub rocker arm, the base end of which is supported by the engine body side, and the other of the low speed cam and the high speed cam engages; a coupling between the main rocker arm and the sub rocker arm; A connection switching mechanism for releasing the engagement, and a hydraulic control device for controlling the operation of the connection switching mechanism ;
The valve train for an internal combustion engine, wherein the hydraulic control device is disposed in a space formed by offsetting each of the camshafts in the axial direction of the camshaft between the camshafts .