Patent Application
20080202458
The present application claims priority under 35 USC 119 to Japanese Patent Application No. 2007-047560 filed on Feb. 27, 2007 the entire contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to an engine having a valve stopping mechanism capable of stopping operation of intake/exhaust valves for opening/closing a communication part between an engine cylinder chamber and an intake or exhaust path.
2. Description of Background Art
An engine is known having a valve stopping mechanism for stopping the operation of a part or all of intake/exhaust valves in a state where a valve drive cam rotates in accordance with an operating state of the engine.
As such a valve stopping mechanism, there is a configuration disclosed in JP-A No. H10-184327 wherein the valve stopping mechanism includes a lifter 11a which is reciprocated in a valve opening/closing direction by a valve drive cam 7, a lifter spring 24 for energizing the lifter 11a so that the lifter 11a abuts on the valve drive cam 7, and a plunger 23 sliding in a cylinder hole 21a formed extending at the right angle with the opening/closing direction in the lifter. In the plunger 23, a through hole 23b in which a valve shaft 5a of an exhaust valve 5 can be inserted and a power transmission face 23g on which the tip of the valve shaft 5a abuts are formed.
In the valve stopping mechanism, when the lifter 11a is reciprocated by the valve drive cam 7 in a state where the plunger 23 energized by the plunger spring 25 is moved to a stop position, the valve shaft 5a is inserted in a through hole 23a, and the exhaust valve 5 is held closed irrespective of the reciprocating movement of the lifter 11a, thereby obtaining a cylinder stop state. On the other hand, when the plunger 23 receives hydraulic fluid pressure on the side opposite to the plunger spring 25, the plunger 23 moves to the operating position against energization of the plunger spring 25. In this state, when the lifter 11a is reciprocated by the valve drive cam 7, the valve shaft 5a abuts on the power transmission face 23g and is reciprocated together with the lifter 11a, and the exhaust valve 5 is opened/closed, thereby obtaining a cylinder operating state.
In such a related valve stopping mechanism, the plunger 23 moves to the stop position by being energized by the plunger spring 25 and moves to the operating position by receiving hydraulic fluid from the opposite side. With this configuration, on start of an engine or the like, it takes time for the hydraulic fluid to become larger than the energizing force of the plunger spring. During the time, the valve is not opened/closed, and the cylinder stop state is obtained. Consequently, there is a problem such that it is difficult to obtain a sufficiently large engine output. To be concrete, for example, in the case of driving a hydraulic pump by an engine and generating the hydraulic fluid from a discharge of the hydraulic pump, when the engine is operated at very low speed on start of the engine or the like, it takes time for the hydraulic fluid to become large. During the time, the cylinder stop state is obtained. There is a problem such that it is difficult to increase an engine output.
To improve the steering feel for the driver, it is also requested to promptly switch from a valve stop state to a valve operating state by hydraulic control in response to a request for increasing an engine output of the driver, that is, to promptly switch from a cylinder stop state (state where the valve stops and the cylinder does not operate) to a cylinder operating state (state where the valve is opened/closed and the cylinder operates).
According to an embodiment of the present invention, an engine having a valve stopping mechanism capable of setting a cylinder operating state by opening/closing a valve in accordance with rotation of a crankshaft when hydraulic fluid is low at the time of start of an engine or the like is provided wherein an excellent response of switch from a cylinder stop state to the cylinder operating state is realized.
According to an embodiment of the present invention, an engine includes an intake valve 20 and an exhaust valve 30 provided for a cylinder head of the engine. A valve energizing member, for example, a first intake valve spring 24a and a first exhaust valve spring 34a are provided for energizing the valve in the direction of closing the valve. A valve drive cam is rotated in correspondence with rotation of a crankshaft of the engine. A valve stopping mechanism is provided between the valve drive cam and the valve and, on the basis of a stop hydraulic fluid pressure supplied from the outside and an operation energizing member, for example, plunger springs 47 and 57, for generating an energizing force against the stop hydraulic fluid pressure, selectively generating an operating state of opening/closing the valve in response to an operation of the valve drive cam and a stop state of holding the valve in a valve closing position irrespective of the operation of the valve drive cam. A stop hydraulic fluid pressure supply controller is provided for controlling supply of the stop hydraulic fluid pressure. The valve stopping mechanism generates the operating state when the energizing force of the operation energizing member is larger than the press force of the stop hydraulic fluid pressure, and generates the stop state when the press force of the stop hydraulic fluid pressure is larger than the energizing force of the operation energizing member The stop hydraulic fluid pressure supply controller includes a switching member, for example, a spool valve 85, which can be moved between a hydraulic fluid supply position in which a pressure source path is connected to a pressure source for supplying the stop hydraulic fluid pressure and a stop pressure supply path for supplying the stop hydraulic fluid pressure to the valve stopping mechanism are communicated with each other. A hydraulic fluid discharging position for closing the pressure source path and making the stop pressure supply path communicate with the drain side is provided together with a switching energizing member, for example, a spool spring 86, for energizing the switching member to move to the hydraulic fluid supply position side. A switching pressure supply control mechanism, for example, a solenoid mechanism 90, applies a pressure force to move the switching member to the hydraulic fluid discharge position side.
In the engine having such a configuration, preferably, the switching pressure supply control mechanism is constructed by a solenoid valve and, when a solenoid is energized, applies the pressure force to move the switching member to the hydraulic fluid discharge position side.
In the engine, preferably the valve stopping mechanism includes a holder, for example, plunger holders 41 and 51, reciprocated in the direction of opening/closing the valve by the valve drive cam. A stop selecting member, for example, stop selecting plungers 45 and 55, is provided in the holder that is capable of moving between an operating position to open/close the valve in accordance with a reciprocating operation of the holder and a stop position to hold the valve in a valve close position irrespective of the reciprocating operation of the holder. The operation energizing member energizes the stop selecting member to the operation position side, and the stop selecting member which receives the stop hydraulic fluid pressure is pressed to the stop position side against the energizing force of the energizing member.
In this case, preferably, the valve includes a valve body for opening/closing the communication part and a valve stem connected to the valve body and extending toward the valve stopping mechanism. The tip of the valve stem passes through the holder and faces the stop selecting member. In the stop selecting member, a stem abutment face and a stem receiving part are formed. When the stop selecting member is in the operating position, the stem abutment face abuts on the tip of the valve stem and moves the valve in the open/close direction together with the holder. When the stop selecting member is in the stop position, the tip of the valve stem is fit in the stem receiving part, and the stem receiving part moves the holder but maintains the valve closed. The stem abutment face and the stem receiving part are formed adjacent to each other in the direction of moving the stop selecting member, and the stop hydraulic fluid pressure is received on the side opposite to the stem abutment face in the direction of moving the stop selecting member while sandwiching the stem receiving part.
Further, preferably, in the stop selecting member, an energizing member housing part for housing the operation energizing member is formed on the same side as the side on which the stem abutment face is formed in the movement direction of the stop selecting member, and a stem communication hole via which the energizing member housing part and the stem housing part communicate with each other is provided in a position overlapping the stem abutment face in the movement direction.
In the engine having the configuration, the holder may be pressed via a rocker arm which swings by being pressed by the valve drive cam, and reciprocate in the direction of opening/closing the valve. The holder may be disposed in a bottomed cylindrical valve lifter, thereby constructing the valve stopping mechanism, and the valve lifter may be pressed by the valve drive cam so as to reciprocate in the direction of opening/closing the valve together with the holder.
With the engine of the present invention, the valve stopping mechanism is constructed to generate the operating state when the energizing force of the operation energizing member is larger than the press force of the stop hydraulic fluid pressure, and generates the stop state when the press force of the stop hydraulic fluid pressure is larger than the energizing force of the operation energizing member. When the engine is operated at very low speed at the time of start of the engine or the like and the stop hydraulic fluid pressure is low, a valve operating state is generated, and a cylinder operating state is obtained. Consequently, a large engine output can be obtained with reliability as a cylinder operating state upon the start of the engine.
In the stop hydraulic fluid pressure supply controller, the switching member is moved to the hydraulic fluid supply position side by the energizing force of the switching energizing member, and the pressure force is applied from the switching pressure supply control mechanism to move the hydraulic fluid discharge position side. Consequently, at the time of switching the cylinder stop state to the cylinder operating state, the pressure force is applied from the switching pressure supply control mechanism and a control of moving the switching member to the hydraulic fluid discharge position is performed. Since the control of forcedly moving the switching member by using the pressure force is performed, a control of promptly moving the switching member to the hydraulic fluid discharge position can be performed, and the response of a switch from the cylinder stop state to the cylinder operating state can be improved. Consequently, in the case such that the driver performs an operation of opening the throttle in the cylinder operating state, the state is promptly switched to the cylinder operating state, and the response to a request for increasing an engine output can be improved.
In the engine, preferably, the switching pressure supply control mechanism is constructed by a solenoid valve and, when a solenoid is energized, a control of applying the pressure force so as to move the switching member to the hydraulic fluid discharge position side is performed. With this configuration, the cylinder operating state and the cylinder stop state can be easily switched by the control of passing current to the solenoid.
In the engine, preferably, the valve stopping mechanism includes a holder reciprocated by the valve drive cam and a stop selecting member capable of moving between an operating position to open/close the valve in accordance with the reciprocating operation of the holder and a stop position to hold the valve in a valve close position irrespective of the reciprocating operation of the holder. The operation energizing member energizes the stop selecting member to the operation position side, and the stop selecting member which receives the stop hydraulic fluid pressure is pressed to the stop position side against the energizing force of the energizing member. With such a configuration, the operation control of setting the valve stopping mechanism in the stop position or the operating position on the basis of the balance between the energizing member and the stop hydraulic fluid pressure can be performed easily and reliably.
In this case, in the stop selecting member, a stem abutment face and a stem receiving part are formed. When the stop selecting member is in the operating position, the stem abutment face abuts on the tip of the valve stem and moves the valve in the open/close direction together with the holder. When the stop selecting member is in the stop position, the tip of the valve stem is fit in the stem receiving part, and the stem receiving part moves the holder but maintains the valve closed. The stem abutment face and the stem receiving part are formed adjacent to each other, and the stop hydraulic fluid pressure is received on the side opposite to the stem abutment face. With this configuration, in the stop selecting member, the stem abutment face for receiving the press force from the valve stem and the portion for receiving the stop hydraulic fluid pressure are apart from each other via the stem receiving part. Consequently, the influence of the press force acting from the valve stem to the stem abutment face, exerted on the part of receiving the stop hydraulic fluid pressure is suppressed. Therefore, deformation of the portion for receiving the stop hydraulic fluid pressure is small, the sealing performance of the portion is maintained excellent, and durability can be improved.
Further, in the stop selecting member, when the energizing member housing part is formed on the same side as the side on which the stem abutment face is formed, and a stem communication hole is provided in a position overlapping the stem abutment face, the stem communication hole becomes longer, the weight of the stop selecting member can be reduced by that amount, and response at the time of moving the stop selecting member improves. Thus, the weight of the whole valve stop mechanism is reduced.
The configuration can be applied to the valve opening/closing mechanism of the rocker arm driving type in which the holder is reciprocated via a rocker arm. The configuration can be also applied to a valve opening/closing mechanism of a cam direct driving type in which a holder is disposed in a valve lifter and the valve lifter is pressed by a valve drive cam and is reciprocated.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:
Preferred embodiments of the present invention will be described hereinbelow with reference to the drawings.
A cylinder head 10 is coupled to the top face of the cylinder block 1. In a state where the cylinder head 10 is attached, a combustion chamber 3 is formed in a portion surrounded by the cylinder hole 1a and facing the top face of the piston 2. An intake path 11 and an exhaust path 12 that communicate with the combustion chamber 3 are formed in the cylinder head 10. In the communication part among the intake path 11, the exhaust path 12, and the combustion chamber 3, an intake valve 20 and an exhaust valve 30 for opening/closing an intake port 11a and an exhaust port 12a forming the communication part are provided.
The intake valve 20 has a valve body 21 openably closing the intake port 11a and a rod-shaped valve stem 22 connected integrally with the valve body 21 and extending therefrom. The valve stem 22 is slidably guided by a cylindrical stem guide 23 attached to the cylinder head 10, and the intake valve 20 is slidable in the extension direction of the valve stem 22. The tip of the valve stem 22 is energized in the valve closing direction (upward direction in the diagram) by a first intake valve spring (valve energizing member) 24a via a retainer 25. In a free state, the valve body 21 closes the intake port 11a.
Similarly, the exhaust valve 30 has a valve body 31 openably closing the exhaust port 12a and a rod-shaped valve stem 32 connected integrally with the valve body 31 and extending therefrom. The valve stem 32 is slidably guided by a cylindrical stem guide 33 attached to the cylinder head 10, and the exhaust valve 30 is movable in the extension direction of the valve stem 32. The tip of the valve stem 32 is energized in the valve closing direction (upward direction in the diagram) by a first exhaust valve spring (valve energizing member) 34a via a retainer 35. In a free state, the valve body 31 closes the exhaust port 12a.
In the cylinder head 10, a guide hole 13, extending coaxially from the attachment part of the stem guide 23 for the intake valve 20 to the upper side (outside), is formed so as to penetrate to the top face side. An intake valve stopping mechanism 40 is disposed slidable in the axial direction in the guide hole 13. On the top face side of the cylinder head 10, a camshaft 6 is disposed so as to extend in the crankshaft direction (direction perpendicular to the drawing face), and an intake valve drive cam 8 provided for the camshaft 6 faces the top end of the intake valve stopping mechanism 40 (refer to
Similarly, a guide hole 14 extending coaxially from the attachment part of the stem guide 33 for the exhaust valve 30 to the upper side (outside) is formed so as to penetrate to the top face side. An exhaust valve stopping mechanism 50 is disposed slidable in the axial direction in the guide hole 14. On the top face side of the cylinder head 10, a rocker arm mechanism 70 having a rocker arm 72 slidably supported by a supporting shaft 71 so as to extend in the crankshaft direction (direction perpendicular to the drawing face) is provided. A cam follower 73 is rotatably attached to one end (right end) 72a of the rocker arm 72, and the cam follower 73 abuts on cam faces 7a and 7b of an exhaust valve drive cam 7 provided for the camshaft 6. A press member 74 is attached to the other end 72b of the rocker arm 72, and the lower end of the press member 74 faces the upper end of the exhaust valve stopping mechanism 50. The press member 74 is screwed in the other end 72b of the rocker arm 72. By adjusting the screw amount, the amount of downward projection can be adjusted. Consequently, a groove 74a to which a driver or the like is inserted is formed in the upper end of the press member 74.
The exhaust valve stopping mechanism 50 is energized toward the rocker arm side (toward the upper side in the drawing) by a second exhaust valve spring 34b disposed in the guide hole 14, and the upper end face of the exhaust valve stopping mechanism 50 is in contact with the press member 74 to press the press member 74 upward, and the rocker arm 72 is energized so as to swing clockwise in the diagram, thereby making the cam follower 73 abut on the cam faces 7a and 7b of the exhaust valve drive cam 7.
A cylinder head cover 5 is coupled to the top face of the cylinder head 10 so as to cover the cam shaft 6, the rocker ram mechanism 70, and the like. Although not shown, a spark plug facing the combustion chamber 3 is attached to the cylinder head 10, and an intake pipe connected to the intake path 11 and an exhaust pipe connected to the exhaust path 12 are attached to the cylinder head 10. To the intake pipe, an air cleaner, a throttle valve, a fuel injection valve, and the like are attached, with the air-fuel mixture of fuel and air being supplied to the combustion chamber 3 in accordance with the operation of the engine E. Combustion gas generated in the combustion chamber 3 is exhausted from the exhaust passage 12 to the outside via the exhaust pipe.
In the engine having the above configuration, first, the configuration of opening/closing the exhaust valve 30 via the exhaust valve stopping mechanism 50 by the rocker arm mechanism 70 will be described in detail hereinbelow with reference to
The exhaust valve stopping mechanism 50 has, as shown in
One end of the plunger hole 52a formed in the plunger holder 51 is open and the other end is closed. The plunger spring 57 is attached into the plunger hole 52a so as to abut on the close wall. After that, the stop selecting plunger 55 is slidably fit in the plunger hole 52a. In the stop selecting plunger 55, a slit 55c extending in the radial direction is formed on one end side in the axial direction (the right end side in the diagram). A spring receiving recess 55d for receiving the plunger spring 57 is formed on the other end side (the left end side in the diagram). Further, a plunger-side stem receiving hole 55a extending orthogonally and passing the center of the axis is formed in the center portion in the axial direction. The size of the plunger-side stem receiving hole 55a is set larger than the diameter of the end of the valve stem 32 of the exhaust valve 30 so that, as will be described later, the tip of the valve stem 32 can project into the plunger-side stem receiving hole 55a. The lower end opening of the plunger-side stem receiving hole 55a is cut in a plane, thereby forming a step abutment face 55b.
In the plunger holder 51, further, a pin hole 52c is formed that is positioned near the open end of the plunger hole 52a, crossing the center of the plunger hole 52a, and penetrating in the vertical direction. A stopper pin 53 is fit in the pin hole 52c. The stopper pin 53 is fit in the slit 55c in the stop selecting plunger 55 fit in the plunger hole 52a. The stop selecting plunger 55 is pressed to the right side in the diagram by the plunger spring 57, and the bottom of the slit 55c abuts on the stopper pin 53 and is held in the position shown in
On the other hand, a ring-shaped hydraulic fluid receiving groove 51c is formed in an intermediate portion on the cylindrical peripheral face of the plunger holder 51. A cylindrical upper guide wall 51a and a cylindrical lower guide wall 51b are formed with the hydraulic fluid receiving groove 51c therebetween. When the plunger holder 51 is fit in the guide hole 14, the upper and lower guide walls 51a and 51b arc guided so as to be slidably fit in the guide hole 14, and the plunger holder 51 can smoothly slide in the guide hole 14. The plunger hole 52a is open to the inside of the hydraulic fluid receiving groove 51c.
In the cylinder head 10, an exhaust valve hydraulic fluid supply path 16 is formed, which supplies exhaust valve stop hydraulic fluid supplied from a stop hydraulic fluid pressure supplying device 80 which will be described later into the hydraulic fluid receiving groove 51c in the plunger holder 51. A front-end fluid passage 16a of the exhaust valve hydraulic fluid supply path 16 is open to the inside of the guide hole 14 and is communicated with the hydraulic fluid receiving groove 51c in this portion. The plunger holder 51 is pressed by the rocker arm mechanism 70 and slides vertically in the guide hole 14. When the plunger holder 51 moves upward as shown in
Next, a stop hydraulic fluid pressure supplying device 80 for the exhaust valve performs control so as to supply an exhaust valve stop hydraulic fluid pressure to the exhaust valve hydraulic fluid supply path 16. The stop hydraulic fluid pressure supplying device 80 will be described with reference to
In the stop hydraulic fluid pressure supplying device 80, an inlet port 82a connected to a stop hydraulic pressure supply source P for supplying the stop hydraulic fluid whose pressure is adjusted to not-shown predetermined hydraulic pressure, an outlet port 82b is connected to the exhaust valve hydraulic fluid supply path 16, and a drain port 82c is connected to the drain side are connected to a spool hole 81a as shown in the diagram. By performing a control of laterally sliding the spool valve 85 in the spool hole 81a, a hydraulic fluid supply stop state (state shown in
In the valve body 81, a first bypass 83a and a second bypass 83b are formed. The first bypass 83a is communicated with the inlet port 82a and the outlet port 82b via small holes 82d and 82e and is provided with, at its end, an open/close port member 84 having an open/close hole 84a which is opened/closed by a poppet 91 of the solenoid mechanism 90. The second bypass 83b makes the right-side space of the open/close port member 84 and the right end of the spool hole 81a communicate with each other.
The solenoid mechanism 90 has a solenoid 92 energized by power supplied via a cable (not shown) connected to a connector 93, the poppet 91 pulled to the right by reception of the excitation force of the solenoid 92, and a poppet spring 94 for energizing the poppet 91 to the left. At the left end of the poppet 91, an open/close projection 91a which projects into the open/close hole 84a from the right side and closes the open/close hole 84a is formed on the left end of the poppet 91. In a non-energizing state of the solenoid 92, the poppet 91 is moved to the left by being energized by the poppet spring 94, and the open/close projection 91a enters the open/close hole 84a to close the open/close hole 84a. On the other hand, when the solenoid 92 is energized, the poppet 91 is moved to the right against the force of the poppet spring 94, and the open/close projection 91a is apart from the open/close hole 84a.
As a result, the stop hydraulic fluid pressure of the hydraulic fluid in the spool fluid chamber 81b moves the spool valve 85 to the left against the force of the spool spring 86 and is positioned in the position in
Since the spool valve 85 is forcedly moved to the left by using the stop hydraulic fluid pressure of the hydraulic fluid supplied into the spool fluid chamber 81b, by properly setting the degree of the stop hydraulic fluid pressure, the spool valve 85 can be moved to the left at an arbitrary speed. In the embodiment, by rapidly moving the spool valve 85 to the left and promptly discharging the hydraulic fluid in the hydraulic fluid supply path 16 connected to the outlet port 82b to the drain side, the fluid pressure acting on the stop selecting plunger 55 is rapidly decreased. It quickens the movement of the stop selecting plunger 55 by the force of the plunger spring 57 at the time of shift from the stop state of the exhaust valve 30 to the operation state, and the response is increased.
On the other hand, the non-energization state of the solenoid 92 is shown in
As a result, the spool valve 85 is moved to the right by the force of the spool spring 86 to the position of
Next, the intake valve stopping mechanism 40 will be described with reference to
The intake valve stopping mechanism 40 has a bottomed cylindrical valve lifter 48 slidably fit in the guide hole 13. A plunger holder 41 is fit in an insertion hole 48a formed in the valve lifter 48. The plunger holder 41 has a configuration almost the same as that of the plunger holder 51 of the exhaust valve stopping mechanism 50. In the plunger holder 41, a plunger hole 42a extending in the direction orthogonal to the sliding direction of the valve lifter 48 is formed so as to penetrate. A stop selecting plunger 45 is slidably fit in the plunger hole 42a and is energized to one side in the sliding direction (to the left in the diagram) by a plunger spring 47. In the plunger holder 41, a holder-side stem receiving hole 42b passing the center of the outer cylindrical shape and penetrating in the vertical direction is formed, and the upper end abuts on the bottom face of the valve lifter 48. The holder-side stem receiving hole 42b is set larger than the diameter of the tip of the valve stem 22 of the intake valve 20. As will be described later, the size of the tip of the valve stem 22 is set so that it can project to the inside of the holder-side stem receiving hole 42b and be received.
In the stop selecting plunger 45, a slit 45c extending in the radial direction is formed on one end side in the axial direction (the left end side in the diagram). On the other end side (the right end side in the diagram), a plunger-side stem receiving hole 45a, receiving the plunger spring 47 and extending orthogonally and passing the center of the axis, is formed in the center portion in the axial direction. The size of the plunger-side stem receiving hole 45a is set larger than the diameter of the end of the valve stem 22 of the intake valve 20 so that, as will be described later, the tip of the valve stem 22 can project into the plunger-side stem receiving hole 45a. The lower end opening of the plunger-side stem receiving hole 45a is cut in a plane, thereby forming a step abutment face 45b.
In the plunger holder 41, further, a pin hole 42c positioned near the open end of the plunger hole 42a, crossing the center of the plunger hole 42a, and penetrating in the vertical direction is formed. A stopper pin 43 is fit in the pin hole 42c. The stopper pin 43 is fit in the slit 45c in the stop selecting plunger 45 fit in the plunger hole 42a. The stop selecting plunger 45 is pressed to the left side in the diagram by the plunger spring 47, and the bottom of the slit 45c abuts on the stopper pin 43 and is held in the position shown in
On the other hand, a ring-shaped hydraulic fluid receiving groove 41c is formed in an intermediate portion on the cylindrical peripheral face of the plunger holder 41. In the state where the plunger holder 41 is fit in the insertion hole 48a in the valve lifter 48, the hydraulic fluid receiving groove 41c faces a communication hole 48b formed in the outer periphery of the valve lifter 48. In the cylinder head 10, an intake valve hydraulic fluid supply path 17 for supplying passage hydraulic fluid supplied from the stop hydraulic fluid pressure supplying device 80 is formed. A front-end fluid passage 17a of the intake valve hydraulic fluid supply path 17 is connected to a hydraulic fluid receiving groove 17b formed in a ring shape in the guide hole 13 and, in this part, communicated with the communication hole 48b in the valve lifter 48.
A top face 48c of the valve lifter 48 is pressed by the intake valve drive cam 8 provided for the camshaft 6 and vertically slides and moves in the guide hole 13e together with the plunger holder 41. During the vertical movement, the communication hole 48b is at least partly communicated with the hydraulic fluid receiving groove 17b. The intake valve stop hydraulic fluid supplied via the hydraulic fluid supply path 17 is supplied from the communication hole 48b into the hydraulic fluid receiving groove 41c. The intake valve stop hydraulic fluid supplied into the hydraulic fluid receiving groove 41c enters the plunger holder 42a, and the hydraulic fluid acts on the left end of the stop selecting plunger 45 to press it to the right direction.
The operation of the valve when the engine E constructed as described above operates will be described hereinbelow. First, the operation in a state where the intake valve stop hydraulic fluid is not supplied to the exhaust valve hydraulic fluid supply path 16 and the intake valve hydraulic fluid supply path 17 will be described. As described above, when the hydraulic fluid is not supplied to the exhaust valve hydraulic fluid supply path 16, in the exhaust valve stopping mechanism 50, a press force overcoming the force of the plunger spring 57 based on the hydraulic fluid pressure is not generated at the end on the side where the slit 55c in the stop selecting plunger 55 fit in the plunger hole 52a is provided. As shown in
When the engine E is operated in this state, the camshaft 6 is rotated in correspondence with the rotation of the crankshaft, and the rocker arm 72 is made swing by the exhaust valve drive cam 7 provided for the camshaft 6. More specifically, in a state where the cylindrical cam face 7a of the exhaust valve drive cam 7 abuts on the cam follower 73, the rocker arm 72 is in the position shown in
At this time, the exhaust valve stopping mechanism 50 is pushed upward by the second exhaust valve spring 34b and the abutment plate 54 abuts on the lower end face of the press member 74. Consequently, the exhaust valve stopping mechanism 50 vertically slides in the guide hole 14 together with the vertical movement of the press member 74. On the other hand, when the press member 74 is in the upward movement position shown in
When the press member 74 is moved downward from the upper movement position shown in
When the exhaust valve 30 is opened/closed as described above, the stem abutment face 55b receives the press force from the valve stem 32 (press force reaction of the exhaust valve drive cam 7). The part for receiving the exhaust valve stop hydraulic fluid pressure (the right end in the diagram of the stop selecting plunger 55) is apart from the stem abutment face 55b while sandwiching the plunger-side stem receiving hole 55a. Consequently, the influence of the press force (for example, elastic deformation) acting on the stem abutment face 55b on the part for receiving the stop hydraulic fluid pressure is suppressed. Deformation of the right end of the stop selecting plunger 55 is very small, so that sealing performance of the portion is excellently maintained, and durability improves. This point is similarly applied to the stop selecting plunger 45 of the intake valve stopping mechanism 40.
Further, by forming a communication hole 55e connecting the stem receiving hole 55a and the spring receiving recess 55d in an overlap portion in the sliding direction with the stem abutment face 55b in the stop selecting plunger 55, the weight of the stop selecting plunger 55 is reduced. It improves sliding response of the stop selecting plunger 55. Further, the weight of the whole exhaust valve stopping mechanism 50 is reduced, and operation response of the exhaust valve 30 also improves. This point is also similarly applied to the intake valve stopping mechanism 40 and the stop selecting plunger 45.
The intake valve stopping mechanism 40 also performs similar operations. More specifically, since the fluid pressure does not act on the left end of the stop selecting plunger 45, the stop selecting plunger 45 is moved to the left by the force of the plunger spring 47 and positioned in the operating position shown in
When the engine E is operated in this state and the camshaft 6 is rotated in correspondence with rotation of the crankshaft, the intake valve stopping mechanism 40 is lifted by the second intake valve spring 24b and the top face 48c of the valve lifter 48 abuts on the intake valve drive cam 8, so that the valve lifter 48 is pressed downward by the intake valve drive cam 8, and the intake valve mechanism 40 is moved in the vertical direction. That is, when the cylindrical cam face 8a of the intake valve drive cam 8 abuts on the top face 48c of the valve lifter 48, the intake valve stopping mechanism 40 is moved upward. When the projected cam face 8b abuts on the top face 48b, the intake valve stopping mechanism 40 is moved downward.
On the other hand, when the intake valve stopping mechanism 40 is in the upper movement position shown in
When the intake valve stopping mechanism 40 is moved downward from the upper movement position shown in
As described above, in a state where the intake valve stopping hydraulic fluid is not supplied to the exhaust valve hydraulic fluid supply path 16 and the intake valve hydraulic fluid supply path 17, the engine E is operated. In correspondence with rotation of the crankshaft, the cam shaft 6 is rotated. By the exhaust valve drive cam 7 provided for the cam shaft 6, the rocker arm 72 is allowed to swing to open/close the exhaust valve 30. By the intake valve drive cam 8, the intake valve 20 is opened/closed. In the cylinder, normal operation is performed.
Next, the case where the exhaust valve hydraulic fluid is supplied from the stop hydraulic fluid pressure supplying device 80 to the exhaust valve hydraulic fluid supply path 16 and the intake valve stop hydraulic fluid is supplied from the stop hydraulic fluid pressure supplying device 80 to the intake valve hydraulic fluid supply path 17 will be described. A control is performed to simultaneously stop the intake valve 20 and the exhaust valve 30 by supplying the stop hydraulic fluid simultaneously from the stop hydraulic fluid pressure supplying device 80 to the exhaust valve hydraulic fluid supply path 16 and the intake valve hydraulic fluid supply path 17.
Amen the exhaust valve stop hydraulic fluid is supplied to the exhaust valve hydraulic fluid supply path 16, in the exhaust valve stopping mechanism 50, the stop selecting plunger 55 fit in the plunger hole 52a receives the press force generated by the hydraulic fluid pressure, is moved to the left against the force of the plunger spring 57 and is positioned in the stop position, as shown in
When the engine E is operated in this state, the camshaft 6 is rotated in correspondence with rotation of the crankshaft, and the rocker arm 72 is swung by the exhaust valve drive cam 7, as described above, the exhaust valve stopping mechanism 50 is pressed by the press member 74 and slides vertically in the guide hole 14. However, when the exhaust valve stopping mechanism 50 is moved in the vertical direction and moved from the position shown in
As a result, even when the camshaft 6 is rotated, the rocker arm 72 is swung by the exhaust valve drive cam 7, and the exhaust valve stopping mechanism 50 slides vertically in the guide hole 14, the exhaust valve 30 is held while closing the exhaust port 12a with the valve body 31. That is, the exhaust valve 30 is stopped in a closed state.
The intake valve stopping mechanism 40 also performs similar operations. More specifically, when the stop hydraulic fluid pressure acts on the left end of the stop selecting plunger 45, the stop selecting plunger 45 receives the hydraulic pressure, is moved to the right against the force of the plunger spring 47, and is positioned in the stop position shown in
When the engine E is operated in this state and the camshaft 6 is rotated in correspondence with rotation of the crankshaft, the valve lifter 48 is pressed downward by the intake valve drive cam 8. Even when the intake valve mechanism 40 is moved vertically, the tip of the valve stem 22 of the intake valve 20 enters the holder-side stem receiving hole 42b and also the plunger-side stem receiving hole 45a. Consequently, the intake valve 20 is held while being lifted by the first intake valve spring 24a. As a result, even when the camshaft 6 is rotated and the intake valve stopping mechanism 40 is moved so as to slide in the vertical direction in the guide hole 13 by the intake valve drive cam 8, the intake valve 20 is held while closing the intake port 11a with the valve body 21. That is, the intake valve 20 is held stopped in the closed state.
As understood from the above description, in the engine E described in the embodiment, at the time of operating the engine in a state where the stop hydraulic fluid is not supplied from the stop hydraulic fluid pressure supplying device 80 and the like to the exhaust valve hydraulic fluid supply path 16 and the intake valve hydraulic fluid supply path 17 (or in a state where the internal fluid pressure is low), when the camshaft 6 is rotated according to rotation of the crankshaft, normal operations of opening/closing the intake and exhaust valves 20 and 30 are performed. On the other hand, when the stop hydraulic fluid pressure is supplied from the stop hydraulic fluid pressure supplying device 80 or the like to the exhaust valve hydraulic fluid supply path 16 and the intake valve hydraulic fluid supply path 17, regardless of the rotational drive of the camshaft, the intake and exhaust valves 20 and 30 are always held closed, and the cylinder having the intake and exhaust valves is in a stop state.
Consequently, when the stop hydraulic fluid pressure is low at the start of the engine or the like, the normal operations of opening/closing the intake and exhaust valves 20 and 30 are performed. Also in a very-low-speed operating state at start of the engine or the like, a predetermined large output can be obtained. Thus, an engine having an excellent starting performance is obtained.
At the time of switching a cylinder stop state where the stop hydraulic fluid is supplied from the stop hydraulic fluid supplying device 80 or the like to the exhaust valve hydraulic fluid supply path 16 and the intake valve hydraulic fluid supply path 17 and the intake and exhaust valves 20 and 30 are always held closed to a cylinder operation state where the intake and exhaust valves 20 and 30 are operated by making the exhaust valve hydraulic fluid supply path 16 and the intake valve hydraulic fluid supply path 17 communicate with the drain side in the stop hydraulic fluid pressure supplying device 80 to decrease the hydraulic fluid pressure, as described above, the solenoid 92 is energized in the stop hydraulic fluid pressure supplying device 80 to move the poppet 91 to the right, the fluid pressure is applied to the right end face of the spool valve 85, the spool valve 85 is rapidly moved to the left, and the hydraulic fluid in the valve hydraulic fluid supply path 16 and the intake valve hydraulic fluid supply path 17 is forcedly and promptly discharged to the drain side. Consequently, response of a switch from the cylinder stop state to the cylinder operation state is high. When the driver performs an operation of opening the throttle in the cylinder stop operation state, the state is promptly shifted to the cylinder operation state by movement of the stop selecting plunger 55 by the energizing force of the plunger spring 57. Thus, response to a request for increasing an output of the engine improves.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-047560 | Feb 2007 | JP | national |
