JP2017155620A - Variable cycle engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the change of a combustion cycle by using a cam having one cam crest.SOLUTION: A variable cycle engine capable of changing a combustion cycle, includes: a cam; a cam shaft supporting the cam; a rocker arm or a valve lifer, and a lost motion mechanism. The cam has one cam crest. The cam shaft is configured to transmit the driving force of a crank shaft and rotate at rotation speed same as the crank shaft. The locker arm or the valve lifter is disposed so as to abut on the cam, and by transmitting the lift amount of the cam crest to drive a valve. The lost motion mechanism stops the driving of the valve by the locker arm or the valve lifter by at a predetermined timing.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a variable cycle engine.

  2. Description of the Related Art Conventionally, a variable cycle engine that can operate by changing a combustion cycle between 4 cycles and 8 cycles or between 4 cycles and 6 cycles is known. For example, Patent Document 1 discloses a variable cycle engine in which the combustion cycle can be changed between 4 cycles and 6 cycles. In the variable cycle engine of Patent Document 1, the camshaft is configured to rotate once while the crankshaft rotates three times. A cam having three cam peaks and a cam having two cam peaks are attached to the camshaft in a switchable manner with respect to each of the intake valve and the exhaust valve. In the variable cycle engine of Patent Document 1, the combustion cycle is changed by switching the cam to three ridges during four-cycle operation and to two hills during six-cycle operation.

JP 2011-074873 A Japanese Patent Laying-Open No. 2015-063976 JP 2014-074334 A

  Patent Document 1 enables switching between 4-cycle operation and 6-cycle operation by switching between two types of cams having a plurality of cam peaks. However, a cam having a plurality of cam ridges is harder to machine than a single cam. Therefore, the use of a plurality of types of cams having a plurality of cam ridges as in the technique of Patent Document 1 is not preferable from the viewpoint of facilitating cam machining.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a variable cycle engine which is improved so that a combustion cycle can be changed using a cam having one cam peak.

  In order to achieve the above object, the present invention is a variable cycle engine capable of changing a combustion cycle, and includes a cam, a cam shaft that supports the cam, a rocker arm or a valve lifter, and a lost motion mechanism. The cam has one cam peak. The camshaft is configured to rotate at the same rotational speed as the crankshaft when the driving force of the crankshaft is transmitted. The rocker arm or valve lifter is disposed in contact with the cam and drives the valve by transmitting the lift amount of the cam crest. The lost motion mechanism stops the driving of the valve by the rocker arm or the valve lifter at a predetermined timing.

  According to the present invention, the camshaft supporting one cam is rotated at the same rotational speed as the crankshaft, and the valve is driven to open and close by the lost motion mechanism at a desired timing according to the combustion cycle. Can be stopped. Therefore, it is possible to realize a variable cycle engine capable of switching the combustion cycle by using a single cam that is easy to cam.

It is a schematic diagram for demonstrating the structure of the variable cycle engine of Embodiment 1. FIG. It is a schematic diagram for demonstrating the cam shape of the variable cycle engine of Embodiment 1. FIG. It is a figure for demonstrating operation | movement of the intake / exhaust valve | bulb when not performing a lost motion of the variable cycle engine of Embodiment 1. FIG. FIG. 3 is a diagram for explaining the operation of intake / exhaust valves during four-cycle operation of the variable cycle engine of the first embodiment. FIG. 3 is a diagram for explaining the operation of intake / exhaust valves during six-cycle operation of the variable cycle engine of the first embodiment. FIG. 3 is a diagram for explaining the operation of intake / exhaust valves during six-cycle operation of the variable cycle engine of the first embodiment. FIG. 3 is a diagram for explaining the operation of intake / exhaust valves during six-cycle operation of the variable cycle engine of the first embodiment. FIG. 6 is a schematic diagram for explaining a configuration of a variable cycle engine of a second embodiment. FIG. 6 is a diagram for explaining the operation of intake and exhaust valves during a two-cycle operation of the variable cycle engine of the second embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof is simplified or omitted.

Embodiment 1 FIG.
FIG. 1 is a schematic diagram for explaining the configuration of the variable cycle engine of the first embodiment. FIG. 1 shows only the configuration of one valve 10 and a portion for driving the valve 10 in order to explain the characteristic configuration of the first embodiment. However, the configuration shown in FIG. 1 is installed in all intake valves and exhaust valves of the variable cycle engine of the present embodiment. The variable cycle engine of the present embodiment is used by being mounted on a vehicle.

  As shown in FIG. 1, the valve 10 (intake valve or exhaust valve) is connected to a rocker arm 12 for driving the valve 10 to open and close. A cam 16 is in contact with the rocker arm 12.

  2A and 2B are diagrams for explaining the shape of the cam according to the first embodiment. FIG. 2A shows the shape of the cam used on the intake valve side, and FIG. 2B shows the shape of the cam used on the exhaust valve side. Shows the shape of the cam. As shown in FIG. 2, the cam 16 has a base circle portion 16a and a cam crest 16b on both the intake valve and exhaust valve sides. In the surface shown in FIG. 2, the base circle portion 16 a has a circular shape centered on the axis of the camshaft 14. The cam crest 16b has a shape that smoothly connects to the base circle portion 16a and projects outward from the base circle portion 16a. Each cam 16 has one cam crest 16b. The central angle of the cam crest 16b, which is the part that lifts the valve 10, is 260 degrees for the cam 16 on the intake valve side and 230 degrees for the cam on the exhaust valve side.

  Again referring to FIG. 1, the cam 16 is supported on the camshaft 14. The camshaft 14 is connected to a crankshaft (not shown) with a chain or the like, and is configured to rotate in synchronization with a ratio of 1: 1 by transmitting the driving force of the crankshaft. That is, when the crankshaft rotates, the camshaft 14 rotates at the same speed as the crankshaft.

  A clearance adjusting HLA 20 is provided on the fulcrum side of the rocker arm 12. The HLA 20 is housed in the lost motion housing 22. The lost motion housing 22 is provided with a spring 24 and a seal 26. The spring 24 is installed so as to contact the HLA 20 and biases the HLA 20 toward the rocker arm 12.

  An oil pump 30 is connected to a hydraulic chamber 28 formed by the HLA 20 and the lost motion housing 22, and oil is supplied from the oil pump 30 via an oil check valve 32. An electromagnetic valve 34 is installed in the hydraulic chamber 28. A lost motion mechanism that stops the driving of the valve 10 by the rocker arm 12 at a predetermined timing by the HLA 20, the lost motion housing 22, the spring 24, the seal 26, the hydraulic chamber 28, the oil pump 30, the oil check valve 32, and the electromagnetic valve 34 is provided. Composed.

  When the solenoid valve 34 is closed, the oil in the hydraulic chamber 28 is sealed in the hydraulic chamber 28 and the HLA 20 is fixed. As a result, the fulcrum side of the rocker arm 12 is fixed, and the pressing force of the cam 16 against the rocker arm 12 is transmitted to the valve 10 by the rocker arm 12, and the valve 10 is driven to open and close.

  On the other hand, when the solenoid valve 34 is opened, the oil in the hydraulic chamber 28 is released. As a result, the HLA 20 becomes movable, the pressing force of the cam 16 against the rocker arm 12 is absorbed on the HLA 20 side, and the valve 10 is not driven. Hereinafter, the opening / closing driving stop of the valve by opening the electromagnetic valve 34 is also referred to as “lost motion”.

  FIG. 3 is a diagram for explaining the valve lift amount of the intake / exhaust valve when the lost motion is not performed. In FIG. 3, IN represents the valve lift amount of the intake valve, and EX represents the valve lift amount of the exhaust valve. In the present embodiment, the camshaft 14 is configured to rotate once while the crankshaft rotates once. Therefore, in a state where the solenoid valve 34 is closed and no lost motion occurs, the intake valve is lifted for 260 CA and the exhaust valve is lifted for 230 CA while the crankshaft rotates once.

  Accordingly, when the intake / exhaust valves are continuously opened and closed without lost motion, as shown in FIG. 3, the intake valve and the exhaust valve are rotated twice during the crankshaft, that is, four strokes per cycle. Then, the valve is opened and closed twice in one cycle, and one of the valves is always open, that is, there is no compression stroke. For example, when the engine decelerates, the engine friction can be reduced by setting the state shown in FIG.

  FIG. 4 is a diagram for explaining the operation of the intake / exhaust valves during four-cycle operation. In FIG. 4, IN represents the valve lift amount of the intake valve, EX represents the valve lift amount of the exhaust valve, and Δ represents the ignition timing. In the following, “4-cycle operation” means 4-stroke 1-cycle operation in which one combustion cycle is composed of four strokes of intake, compression, expansion, and exhaust, and “6-cycle operation” It shall mean 6 stroke 1 cycle operation in which one combustion cycle is composed of 6 strokes.

  As shown in FIG. 4, in the four-cycle operation, the solenoid valve 34 is operated so that each of the intake valve and the exhaust valve is lost once every two rotations. Specifically, for the intake valve, the opening / closing operation on the side having the lift amount peak in the expansion stroke is stopped, and for the exhaust valve, the opening / closing operation on the side having the lift amount peak in the compression stroke is stopped. The lost motion is executed once every two times. Thereby, in one combustion cycle consisting of four strokes, the intake valve is lifted once in the intake stroke, and the exhaust valve is lifted once in the exhaust stroke.

  FIGS. 5-7 is a figure for demonstrating the opening / closing pattern of the intake / exhaust valve | bulb at the time of 6 cycle operation | movement. 5 to 7, IN represents the valve lift amount of the intake valve, EX represents the valve lift amount of the exhaust valve, and Δ represents the ignition timing.

  In the pattern of FIG. 5, the lost motion is performed once during the rotation of the crankshaft 3 and the intake / exhaust valves are stopped. Specifically, the 6-cycle operation of FIG. 5 includes six strokes of intake, compression, expansion, exhaust, and intake and exhaust for scavenging without fuel injection. In the 6-cycle operation of FIG. 5, the opening / closing operation at the timing having the lift amount peak in the expansion stroke is stopped for the intake valve, and the opening / closing operation at the timing having the lift amount peak in the compression stroke is stopped for the exhaust valve. Is done.

  As a result, the intake valve is lifted once in the intake stroke in one combustion cycle, and then the lost motion is performed to stop the opening and closing drive of the valve, and is lifted again in the intake stroke for scavenging. The The exhaust valve is lifted once in the exhaust stroke, and then lifted once in the exhaust stroke for scavenging. Thereafter, the lost motion is performed for one rotation, and the opening / closing drive of the valve is stopped. By having the second intake and exhaust strokes in this way, scavenging is sufficiently performed, so that variations in combustion due to variations in residual gas can be suppressed.

  In the pattern of FIG. 6, the lost motion is performed twice for three rotations for each of the intake and exhaust valves. The 6-cycle operation in FIG. 6 includes six strokes of intake, compression, expansion, recompression, reexpansion, and exhaust. After the intake valve is lifted once in the intake stroke, a lost motion is performed and the intake valve is maintained in a closed state for two rotations. On the other hand, the exhaust valve is lifted once in the exhaust stroke, and then the lost motion mechanism is operated to maintain the valve closed for two rotations.

  In the pattern of FIG. 7, the intake valve is lost twice every three rotations, and the exhaust valve is lost once every three times. The 6-cycle operation of the pattern of FIG. 7 is composed of six strokes of intake, compression, expansion, exhaust, re-expansion, and exhaust. After the intake valve is lifted in the intake stroke, the lost motion is performed for two rotations and is maintained in the closed state. On the other hand, the exhaust valve is opened and closed at a timing having a lift amount peak in the compression stroke, stopped by the lost motion, lifted in the exhaust stroke, then lifted again in the second exhaust stroke through a re-expansion stroke. .

  The valve pattern during the 6-cycle operation in FIGS. 5 to 7 is appropriately selected according to the engine operating conditions. Moreover, you may make it drive | operate with a different pattern for every cylinder as needed.

  In the present embodiment, both the intake and exhaust valves may be lost while the cylinder deactivation operation is performed. Thereby, the state where the intake / exhaust valve is closed during the cylinder deactivation operation can be continued. Since both valves are closed, oil rise in the combustion chamber can be suppressed. Moreover, since the outflow of the low-temperature air that has not undergone the combustion stroke to the exhaust side can be suppressed, a decrease in the catalyst temperature can be suppressed.

  As described above, in the first embodiment, a four-cycle operation and a six-cycle operation can be realized using a cam having one cam crest.

Embodiment 2. FIG.
FIG. 8 is a schematic diagram for explaining the variable cycle engine of the second embodiment. FIG. 8 shows only one valve and a mechanism for driving the valve. However, the configuration of FIG. 8 is installed for all intake and exhaust valves provided in the variable cycle engine.

  8 is connected to a plunger 52, an oil chamber 54, and a pump plunger 56, and a cam 58 is in contact with the pump plunger 56. The cam 58 has the same configuration as in the first embodiment. The cam 58 is supported on the camshaft 60. Similar to the first embodiment, the camshaft 60 is connected to the crankshaft with a chain or the like so that the driving force of the crankshaft is transmitted, and is rotated synchronously at a ratio of 1: 1. A spring 62 is installed around the pump plunger 56, whereby the pump plunger 56 is urged toward the cam 58. The plunger 52, the oil chamber 54, the pump plunger 56 and the spring 62 constitute a valve lifter.

  Oil is supplied into the oil chamber 54 from an oil pump 64 through an oil check valve 66. A discharge path 68 for discharging oil is connected to the oil chamber 54. An electromagnetic valve 70 for oil discharge control is installed in the discharge path 68. The oil chamber 54, the oil pump 64, the oil check valve 66, the discharge path 68, and the electromagnetic valve 70 constitute a lost motion mechanism.

  FIG. 8 shows a state where the electromagnetic valve 70 is closed. When the solenoid valve 70 is closed and the discharge path 68 is closed, the oil chamber 54 is filled with oil and is in a sealed state. In this case, as the cam 58 rotates, the pressing force by the cam crest is transmitted to the valve 50 via the pump plunger 56, the oil chamber 54, and the plunger 52, and the valve 50 is driven to open and close.

  On the other hand, when the discharge path 68 is opened by opening the electromagnetic valve 70, the oil in the oil chamber 54 can be retracted to the discharge path 68. Therefore, when the electromagnetic valve 70 is opened, even if the cam 58 pushes down the pump plunger 56, the movement is absorbed by the oil chamber 54 and is not transmitted to the plunger 52 and the valve 50, but is lost.

  Also in the mechanism of the second embodiment, a 4-cycle operation and a 6-cycle operation can be realized by performing a lost motion of the intake / exhaust valves at the same timing as in the first embodiment. Further, it is possible to operate without a lost motion when the engine is decelerated, or to perform a lost motion for the entire period and maintain the valve closed during the cylinder deactivation operation.

  Furthermore, in this embodiment, it is possible to execute a two-cycle operation in which one combustion cycle consisting of intake, compression, expansion, and exhaust is performed during two strokes. FIG. 9 is a diagram for explaining the operation of the intake / exhaust valves during the two-cycle operation. In FIG. 9, IN represents the valve lift amount of the intake valve, EX represents the valve lift amount of the exhaust valve, and Δ represents the ignition timing.

  As shown in FIG. 9, during the two-cycle operation, the lost motion is not performed and the electromagnetic valve 70 is maintained in the closed state. Further, as shown in FIG. 9, a variable valve mechanism (VVT) (not shown) retards the valve timing of the intake valve, advances the valve timing of the exhaust valve, and further advances both the valve by electromagnetic valves. Both valves reduce the working angle. As a result, two-cycle operation is realized.

  In the above embodiment, when referring to the number of each element, quantity, quantity, range, etc., the reference is made unless otherwise specified or the number is clearly specified in principle. The invention is not limited to the numbers. Further, the structure and the like described in this embodiment are not necessarily essential to the present invention unless otherwise specified or clearly specified in principle.

10 Valve 12 Rocker arm 14 Camshaft 16 Cam 16a Base circle 16b Cam pile 20 HLA
22 Lost motion housing 24 Spring 26 Seal 28 Hydraulic chamber 30 Oil pump 32 Oil check valve 34 Solenoid valve 50 Valve 52 Plunger 54 Oil chamber 56 Pump plunger 58 Cam 60 Camshaft 62 Spring 64 Oil pump 66 Oil check valve 68 Discharge path 70 Electromagnetic valve

Claims (1)

An engine capable of changing the combustion cycle,
A cam having one cam mountain;
A camshaft that supports the cam and rotates at the same rotational speed as the crankshaft by transmitting a driving force of the crankshaft;
A rocker arm or a valve lifter that is arranged in contact with the cam and transmits a lift amount of the cam crest to drive the valve;
A lost motion mechanism that stops driving the valve by the rocker arm or the valve lifter at a predetermined timing;
Variable cycle engine with

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