JP2808039B2 - 2-4 cycle switching engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention switches between two-cycle operation and four-cycle operation in accordance with the rotational speed and load state of an engine.
The present invention relates to a cycle switching engine.

(Prior Art) A conventional piston reciprocating engine uses one reciprocation of a piston, that is, one revolution of a crankshaft, to suck, compress, explode,
Two-stroke engine that performs the exhaust stroke and two pistons
The engine is roughly classified into a four-cycle engine that performs the above-described four strokes during reciprocation, that is, two rotations of the crankshaft.

In the above-described two-cycle engine, intake and exhaust are performed simultaneously in parallel before and after the bottom dead center of the piston, and an explosion stroke is performed for each revolution of the crankshaft. Can occur.

On the other hand, in the four-stroke engine, the intake and exhaust are performed in independent strokes, so that the gas is sufficiently exchanged, the exhaust gas is cleaner than the two-stroke engine, and the fuel during the high-speed operation of the engine is improved. There is an advantage that the consumption rate is small.

(Problems to be Solved by the Invention) Since the characteristics of the two-cycle engine and the four-cycle engine are different from each other as described above, the two-stroke engine operates as a two-stroke engine during low-speed operation, and operates as four-stroke engine during high-speed operation according to changes in the operating state of the engine. A 2-4 cycle switching engine that operates as a cycle engine can be expected to be an engine that has the advantages of both conventional 2 and 4 cycle engines.

However, it is difficult to change the opening / closing timing of the intake / exhaust valve during the operation of the engine, and an engine having an intake / exhaust valve opening / closing timing changing mechanism that can withstand practical use has not yet been obtained.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a 2-4 cycle switching engine that can be put to practical use.

(Means for Solving the Problems) According to the present invention, there are provided a camshaft for driving the intake and exhaust valves to open and close during a two-cycle operation and a camshaft for driving the intake and exhaust valves to open and close during a four-cycle operation. In the 2-4 cycle switching engine that switches the camshaft, the intake valve and the exhaust valve that are normally biased in the closing direction by the valve spring, and the rotation speed of the crankshaft is reduced by half and transmitted to both the camshafts simultaneously. Opening means for opening and closing the intake valve and the exhaust valve by pressing action of a cam provided on a camshaft provided on a camshaft which contacts the ends of the intake valve and the exhaust valve and opens and closes the intake valve and the exhaust valve during the above-mentioned four-cycle operation. Rocker arm for four-cycle operation, and four cycles in contact with the ends of the intake and exhaust valves The air is sucked through a rocker arm for four-cycle operation by a pressing action of a cam provided on a camshaft provided to open and close an intake valve and an exhaust valve during the two-cycle operation. A rocker arm for two-cycle operation for driving the valve exhaust valve in the opening direction,
First drive control means for controlling on / off transmission of the driving force of the camshaft for the four-cycle operation to the rocker arm for the four-cycle operation, and two-cycle operation for the rocker arm for the two-cycle operation And a second drive control means for controlling the transmission of the driving force of the camshaft on / off.

(Operation) In the 2-4 cycle switching engine of the present invention, two types of camshafts, a camshaft for two-cycle operation and a camshaft for four-cycle operation, are provided in the engine, and only the camshaft according to the operation cycle is provided. , The opening / closing timing of the intake / exhaust valve is changed during the operation of the engine.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a configuration diagram schematically showing an engine according to the present invention.

Reference numeral 1 denotes an engine, which is provided with an intake valve 11 and an exhaust valve 12 similar to those of a normal four-stroke engine.

Reference numeral 2 denotes a turbocharger, which drives an exhaust turbine 22 by exhaust gas exhausted through the exhaust valve 12 and operates a compressor 21 by the driving force to compress compressed supercharged air through the intake valve 11. The engine 1 is supplied to the engine 1.

Reference numeral 23 attached to the turbocharger 2 denotes a rotating electric machine, which operates as a generator when the exhaust gas emission is large and collects the exhaust energy when the exhaust gas emission is small. The motor is operated by the compressor
The supercharging operation of 21 is energized.

The engine 1 has an intake valve 11 and an exhaust valve.
By changing the opening / closing timing with 12, the engine can be operated as a two-cycle engine or a four-cycle engine.

Next, the opening / closing timing of the intake valve 11 and the exhaust valve 12 will be described.

FIG. 2 is a cam profile curve diagram showing a relationship between a lift amount of an intake / exhaust valve and a rotation phase of an engine.
In the figure, I indicates the opening / closing timing of the intake valve 11, and E indicates the opening / closing timing of the exhaust valve 12.

(A) of this figure shows the opening and closing timing of the intake and exhaust valves at the time of four-cycle operation, which is the same as the opening and closing timing of the intake and exhaust valves in a normal four-cycle engine.

(B) shows the opening and closing timing of the intake and exhaust valves during the two-cycle operation.

During the two-cycle operation, the expansion process proceeds, and when the piston approaches the bottom dead center (BDC), the exhaust valve 12 is first opened to exhaust the exhaust gas inside the combustion chamber. At approximately the bottom dead center position, the intake valve 11 is opened, the supercharged air compressed by the compressor 21 is introduced into the combustion chamber, and the exhaust gas remaining in the combustion chamber is forced out. Let it drain.

When exhaust of the exhaust gas is completed, the exhaust valve 12
, And the introduction of the supercharged air into the combustion chamber is continued to fill the combustion chamber with the supercharged air. When the filling is completed, the intake valve 11 is also closed, and the process proceeds to the compression step. still,
TDC indicates top dead center.

Next, a mechanism for changing the opening / closing timing of the intake / exhaust valve will be described.

FIG. 3 is a partial sectional view showing the relationship between the valve and the camshaft.

FIG. 4 is a view schematically showing a rotation drive device for the camshaft.

Incidentally, since both the intake valve 11 and the exhaust valve 12 are driven to open and close by the same mechanism,
Will be described.

Reference numeral 13 denotes a cylinder head, and a valve spring 14 is interposed between the intake valve 11 and the cylinder head 13. Therefore, the intake valve 11 is constantly urged in the closing direction by the expansion force of the valve spring 14.

Reference numeral 3 denotes a camshaft for four-cycle operation, and a cam 3a
Contact with the rocker arm 31 through the
Rocks. The distal end 32 of the rocker arm 31 is in contact with the axial end of the intake valve 11, and the rocker arm 31 swings to open and close the intake valve 11.

Reference numeral 4 denotes a camshaft for two-cycle operation. The camshaft 4 comes into contact with the rocker arm 41 via the cams 4a, 4b and the roller 46 to swing the rocker arm 41. The distal end 42 of the rocker arm 41 is connected to the shaft end of the intake valve 11 via the distal end 32 of the rocker arm 31.
When the rocker arm 41 swings, the intake valve 11
To open and close.

A timing pulley 33 is connected to an end of the camshaft 3 via an electromagnetic clutch 6. The shaft end of the camshaft 4 is connected to a timing pulley 43 via an electromagnetic clutch 60.

Reference numeral 5 denotes a timing pulley that is connected to the crankshaft and rotates at the same speed as the crankshaft, and is configured to interlock with the timing pulley 33 and the timing pulley 43 via a timing belt 51.
The diameter of the timing pulley 33 and the timing pulley 43 is twice the diameter of the timing pulley 5, so that the camshaft 3 and the camshaft 4 rotate at half the rotation speed of the crankshaft. become.

Since the camshaft 3 and the camshaft 4 can be rotated by one timing belt 51 as described above, it is very convenient in terms of engine layout. Also,
As shown in FIG. 2, during the two-cycle operation, the opening / closing period of the intake / exhaust valve is short and the opening / closing speed is high, but since the rotation speed of the camshaft 4 is half that of the crankshaft, the roller 46 The cam profile can be traced accurately without jumping.

Reference numeral 7 denotes a controller, which is an input / output interface that controls input and output of signals to and from the outside, a ROM that stores programs and various data in advance, a CPU that performs calculation processing under programs stored in the ROM, The controller 7 includes a RAM for temporarily storing various data, a control memory for controlling the flow of signals inside the controller 7, and the like.

The controller 7 is connected with a rotation sensor 71 for detecting the rotation speed and phase of the engine, and a load sensor 72 for detecting the load on the engine, and receives detection signals from the sensors.

Then, based on the detection signal, for example, if the operating state of the engine is at low speed and high load, two-cycle operation is selected, and in other cases, four-cycle operation is selected.

When the two-cycle operation is selected, the electromagnetic clutch 60 as the second drive control means is operated to rotate the camshaft 4. When the four-cycle operation is selected, the electromagnetic clutch 6 serving as the first drive control unit is operated to rotate the camshaft 3.

By the way, both the electromagnetic clutch 6 and the electromagnetic clutch 60 can transmit the rotational force and synchronize the rotational phases.

 Next, the structure of the electromagnetic clutch will be described.

FIG. 5 is a diagram schematically showing the structure of the electromagnetic clutch.

The electromagnetic clutch 6 and the electromagnetic clutch 60 have the same structure, and have a clutch plate 61 and a clutch plate 62 therein. Although not shown, the clutch plate 61 and the clutch plate 62 approach each other due to electromagnetic force from an electromagnetic solenoid, and the clutch surface 63 comes in contact with the clutch plate 63 to transmit torque.

Further, a pin 64 and a pin 65 which can enter and exit the clutch plate 61 in response to an external signal are provided at different positions from the center of the clutch plate 61. On the other hand, in the clutch plate 62, slots are provided at positions corresponding to the pins 64 and 65.
66 and a long hole 67 are provided.

When transmitting the rotational force, the clutch plate 61 and the clutch plate 62 are brought into contact with the pin 64 and the pin 65 stored in the clutch plate 61. The contact pressure at this time is set to a low pressure of about 80% to 90% of the pressure at which the clutch plates are completely connected, causing a slip between the clutch plates 61 and 62.

When a biasing force in the protruding direction is applied to the pins 64 and 65 in the state where the slip occurs, the pins 64 and the elongated holes 66 are aligned with each other, and the pins 64 and the elongated holes 67 are aligned with each other. And the pin 65 protrudes. Then, each pin moves inside each long hole due to slippage between the clutch plates, and when each pin hits the end of each long hole, the clutch plates 61 and 62 rotate completely synchronously. Incidentally, the impact force when each pin abuts is alleviated because the clutch plate is already in the half-clutch state, and the pin is not damaged.

Then, when the rotation is performed completely synchronously, the contact pressure between the clutch plates is increased to prevent slippage, thereby completing the linkage.

By the above operation, the camshaft 3 and the camshaft 4 are always connected to the crankshaft in the same phase.

In the above description, the operation of the clutch plate and the pin is performed by an electromagnetic force. However, it is obvious that the operation may be performed by a fluid pressure such as a hydraulic pressure.

Next, another mechanism for changing the opening / closing timing of the intake / exhaust valve will be described.

FIG. 6 is a diagram showing another example of the opening / closing timing changing mechanism.

Reference numeral 3 denotes a camshaft having a cam 3a similar to that in the case of FIG. 3, but in this case, the cam shaft 3 is connected to the timing pulley 33 without the intervention of the electromagnetic clutch 6, so that
It always rotates at half the rotation speed of the crankshaft.

Reference numeral 8 denotes a composite rocker arm, which can swing around a shaft 81. The shaft 81 is provided with two hydraulic paths, and the hydraulic path includes a pipeline 82 and a pipeline 83.
Through a cylinder mechanism 84.

The cylinder mechanism 84 has a piston 85, and a tip 86 of the piston 85, which is a first drive control means.
Is inserted between the camshaft 3 and the composite rocker arm 8 at the forward end position of the piston 85. Therefore, when the piston 85 is at the retracted end position, that is, the position shown in this drawing, the camshaft 3 does not come into contact with the composite rocker arm 8, and the intake valve 11 does not operate. still,
The tip 87 of the composite rocker arm 8 is always in contact with the shaft end of the intake valve 11.

Reference numeral 9 denotes a camshaft having two cams 9a and 9b for two-cycle operation. The camshaft 9 always rotates at the same speed as the camshaft 3 of this embodiment without using an electromagnetic clutch.

Reference numeral 90 denotes a composite rocker arm similar to the composite rocker arm 8, which can swing around a shaft 91. The shaft 91 is provided with two systems of hydraulic paths, and the hydraulic paths are connected to a cylinder mechanism 94 via a pipe 92 and a pipe 93.

The cylinder mechanism 94 has a piston 95, and a roller 96 provided at a tip end of the piston 95, which is a second drive control means, has a forward end position of the piston 95,
That is, it is inserted between the camshaft 9 and the composite rocker arm 90 at the position shown in FIG. Therefore, piston 95
Is in the retracted end position, the camshaft 9 does not come into contact with the composite rocker arm 90, and the intake valve 11 does not operate. The tip of the composite rocker arm 90
97 is always in contact with the upper surface of the tip 87 of the composite rocker arm 8.

By the way, the controller 7 controls the oil pressure of the oil pressure paths provided on the shaft 81 and the shaft 91.

That is, when the controller 7 selects the two-cycle operation, hydraulic pressure is applied to the pipeline 82 to retract the piston 85, and hydraulic pressure is applied to the pipeline 93 to move the piston 95 forward. Then, the state shown in the figure is reached, and the intake valve 11 is driven to open and close by the camshaft 9.

On the other hand, when the controller 7 selects the four-cycle operation, the hydraulic pressure is applied to the pipe 92 to retract the piston 95, and the hydraulic pressure is applied to the pipe 83 to move the piston 85 forward. 3 is driven to open and close.

As described above, the embodiments of the present invention have been described in detail. However, various different embodiments can be easily configured without departing from the spirit of the present invention. It is not limited to a particular embodiment.

(Effects of the Invention) As described above, according to the present invention, two types of camshafts, that is, a camshaft for two-cycle operation and a camshaft for four-cycle operation, are provided in the engine, and the two types of camshafts are provided according to the operation cycle. By operating only the camshaft, the opening / closing timing of the intake / exhaust valve is changed during the operation of the engine, so that the operation cycle can be reliably changed according to the operating state of the engine, and can be put to practical use. A 2-4 cycle switching engine can be provided.

In addition, the camshaft for two-cycle operation and the camshaft for four-cycle operation are simultaneously rotated by one reduction gear, so that the engine can be made compact.
This is extremely convenient in terms of engine layout.

Furthermore, since the camshaft for two-cycle operation is rotated at half the rotation speed of the crankshaft and the cam shape is traced by the roller, the cam shape can be reliably transmitted to the intake and exhaust valves.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an outline of an engine according to the present invention;
FIG. 2 is a cam profile curve diagram showing the relationship between the lift amount of the intake / exhaust valve and the rotational phase of the engine, and FIG.
FIG. 4 is a partial sectional view showing the relationship between the valve and the camshaft,
FIG. 5 is a diagram schematically showing a rotary drive device for a camshaft, FIG. 5 is a diagram schematically showing the structure of an electromagnetic clutch, and FIG. 6 is a diagram showing another example of an opening / closing timing changing mechanism. DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Turbocharger, 3 ... Camshaft, 4 ... Camshaft, 5 ... Timing pulley, 6 ... Electromagnetic clutch, 7 ... Controller, 8 ...
Compound rocker arm, 9 ... Camshaft, 11 ... Intake valve, 12 ... Exhaust valve, 60 ... Electromagnetic clutch, 71 ...
... Rotation sensor, 72 ... Load sensor, 84 ... Cylinder mechanism, 90 ... Compound rocker arm, 94 ... Cylinder mechanism.

Claims (3)

(57) [Claims] 1. A 2-4 cycle switching engine having a camshaft for opening and closing an intake / exhaust valve during a two-cycle operation and a camshaft for opening / closing an intake / exhaust valve during a four-cycle operation. An intake valve and an exhaust valve which are normally biased in a closing direction by a valve spring; transmission means for reducing a rotation speed of a crankshaft by half and transmitting the rotation to the two camshafts at the same time; A rocker arm for four-cycle operation that drives the intake valve and the exhaust valve in the opening direction by pressing a cam provided on a camshaft provided on a camshaft that contacts an end of the valve and that opens and closes the intake valve and the exhaust valve during the four-cycle operation. And an upper part of a rocker arm for four-cycle operation in contact with an end of the intake valve and the exhaust valve. Abutting on
A rocker arm for two-cycle operation that drives the intake valve exhaust valve in the opening direction via a rocker arm for four-cycle operation by a pressing action of a cam provided on a cam shaft that opens and closes the intake valve and exhaust valve during cycle operation; First drive control means for controlling on / off transmission of the driving force of the camshaft for the four-cycle operation to the rocker arm for the four-cycle operation; and two-cycle operation to the rocker arm for the two-cycle operation. A second drive control means for controlling on / off of transmission of drive force of a camshaft for use in a 2-4 cycle switching engine. 2. The apparatus according to claim 1, wherein said first and second drive control means are electromagnetic clutches for controlling on / off of a rotational force from said transmission means to both camshafts. 4-cycle switching engine. 3. The first and second drive control means are interposed between each of the cams provided on each of the camshafts and the rocker arms, and transmit and remove the driving force of each of the cams to each of the rocker arms. The engine according to claim 1, wherein the engine is a member.