The foregoing and additional features and characteristics of the present invention will become more apparent from the following detailed description considered with reference to the accompanying drawings, wherein:
First, engine E to which the valve opening and closing timing control device of the invention is applied will be explained. The engine illustrated in
A phase control unit U is fixed to each one end of the intake side camshafts 12a. The phase control unit U includes a timing sprocket 23 which will be explained later in detail. A normal type-timing sprocket 14 is fixed to each one end of the exhaust side camshafts 12b. The intake side and the exhaust side camshafts 12a and 12b are connected to a crankshaft 11 via a drive force transmitting member such as a timing chain or timing belt 15 which is wound around the timing sprockets 14 and 23 for synchronizing rotation with the rotation of crankshaft 11. A first pump P1 is also connected to the crankshaft 11 via the drive force-transmitting member 15 for synchronizing rotation with the rotation of crankshaft 11.
In
The valve timing control device 1 will be explained hereinafter. In
As shown in
Further, the hydraulic circuit O as shown in
As shown in
The phase control unit U is illustrated in
The inner rotor 3 is integrally assembled to the end of the intake side camshaft 12a. The intake side camshaft 12a is disposed between the cylinder head and head cover portions in each bank Eb1 and Eb2 of the engine block.
The outer rotor 2 is inserted into the inner rotor 3 and relatively rotatable within a predetermined angle range. A rear plate 21 is integrally connected to the outer rotor 2 at one side where the intake side camshaft 12a is to be connected and a front plate 22 is integrally connected to the outer rotor 2 at the opposite side to the location of the rear plate 21. Both rear and front plates 21 and 22 are integrally connected to the outer rotor 2 by means of a screw as shown in
When the crankshaft 11 is rotated, the rotational torque is transmitted to the timing sprocket 23 through the belt or chain 15. The outer rotor 2 is then rotated in an arrowed direction S as shown in
As shown in
A vane groove 31 is provided at the outer periphery of the inner rotor 3 at a portion facing each hydraulic chamber 4. In each vane groove, a vane 32 is slidably inserted in a radial direction. Each vane defines the hydraulic chamber 4 to two chambers, an advance angle chamber 41 and a retard angle chamber 42 in a relative rotational direction (an arrowed direction S1 or S2 in
The advance angle chamber 41 is in communication with an advance angle passage 43 formed in the inner rotor 3, while the retard angle chamber 42 is in communication with a retard angle passage 44. The advance angle passage 43 and the retard angle passage 44 are connected to the hydraulic circuit O as shown in
As shown in
The lock mechanism 5 is provided between the outer rotor 2 and the inner rotor 3 for restraining the displacement of relative rotation therebetween at a predetermined lock phase. The lock phase is set to be the allowable most retarded angle phase position. The lock mechanism 5 includes a lock member 53 slidably provided in a sliding groove 52 formed in the outer rotor 2, a spring 54 for urging the lock member 53 inwardly in a radial direction and the engagement recess portion 51 provided in the inner rotor 3 and engageable with the lock member 53 when the relative rotational phase is in the lock phase position. In this embodiment, the lock member 53 is of a flat plate shape and the sliding groove 52 and the engagement recess portion 51 are shaped accordingly to achieve the locking function. The shapes of these members can be changeable as long as the locking function can be achieved.
The engagement recess portion 51 is provided at the inner rotor 3 and radial inner end of the lock member 53 can be engaged with the recess portion 51. The engagement recess portion 51 is provided at a position where the lock member 52 is engaged under the relative rotation phase being at the lock phase position. The lock member 53 is moved into the engagement recess portion 51 by the urging force of the spring 54 to lock the relative rotation between the inner rotor 3 and the outer rotor 2. Thus the relative rotation is restrained to the lock phase position. The engagement recess portion 51 is in communication with the advance angle passage 43 and the operation fluid from the hydraulic circuit O is supplied to the advance angle passage 43 to force the lock member 53 to be retracted from the engagement recess portion 51 to release the locking condition. In other words, the engagement recess portion 51 is filled with the operation fluid to generate the hydraulic pressure therein to move the lock member 53 from the engagement recess portion 51 by overcoming the spring force of the spring 54 as shown in
The relative rotational phase between the inner and the outer rotors 3 and 2 is locked by the lock mechanism 5 when the engine E is stopped and the operation fluid is not supplied to the phase control unit U as shown in
The lock phase (in this embodiment, the most retarded angle phase) is preferably set to the phase where the valve closing timing of the intake valve 13a becomes the retarded angle side more than a predetermined angle relative to the intake lower dead point. Thus, the phase control unit U fixes the intake side camshaft 12a so that the intake valve closing timing becomes a phase at the retarded angle side more than a predetermined angle relative to the intake lower dead point when the engine E is stopped. In this embodiment, the lock phase is preferably set to the range that the intake valve closing timing is more than 40° and less than 300° in crank angle at the retard side relative to the intake lower dead point. Assuming the exhaust upper dead point being zero (0°), the range becomes more than 220° and less than 300° in crank angle. When the engine environment is relatively good for operation such as when the engine temperature is above a predetermined degree it is preferable to retard the lock phase near the boundary of the retard side where the engine start is possible, such as 90° retarded relative to the intake lower dead point. By setting the lock phase in the above method, at the engine cranking start timing for engine start, the intake side camshaft 12a becomes the phase at very retarded side more than the normal retard phase. In the engine E, the intake valve 13a becomes open at the front half of the engine piston Ep rising process from the intake lower dead point. The compression ratio at the compression upper dead point (ignition point) becomes very low (decompression condition). This can minimize the vibration generated at the engine E immediately after the cranking started.
The hydraulic circuit O will be explained hereinafter. The hydraulic circuit O includes a first pump P1 driven by the engine for supplying the operation fluid, and a second pump P2 driven by a motor M for supplying the operation fluid. The second pump P2 is provided at the downstream of the first pump P1. A reservoir R is provided in a flow passage between the first and second pumps P1 and P2 for reserving the operation fluid therein. In this embodiment, the reservoir tank R corresponds to the fluid reserving means. The hydraulic circuit O includes a first control valve V1 for controlling the supply of operation fluid to the first phase control unit U1, a second control valve V2 for controlling the supply of operation fluid to the second phase control unit U2. The first and the second control valves V1 and V2 control the supply of operation fluid to the hydraulic chamber 4 and the lock mechanism 5 forming the phase control mechanism N of each phase control unit U1 and U2.
The first pump P1 is a mechanical type hydraulic pump driven by the drive force of the crankshaft of the engine E. This first pump P1 suctions operation fluid reserved in the oil pan 61 from the inlet port and ejects the operation fluid to the downstream side from the outlet port. The outlet port of the first pump P1 is connected to the engine lubrication system EL, reservoir tank R and the second control valve V2 through the filter 62. The engine lubrication system EL includes all parts necessary for supplying the operation fluid in the engine E and its surroundings. The reservoir tank R is connected to the first control valve V1 through a bypass passage 63. The first pump P1 supplies the operation fluid to the first phase control unit U1 via reservoir tank R, bypass passage 63 and the first control valve V1 and at the same time supplies the operation fluid to the second phase control unit U2 via the second control valve V2.
On the other hand, the second pump P2 is an electric pump operated by the motor M. The second pump P2 is operated according to operation signals from the control device ECU regardless of the engine E condition. The second pump P2 suctions operation fluid from the reservoir tank R at the inlet port and ejects the operation fluid to the downstream side from the outlet port. The outlet port of the second pump P2 is connected to the first control valve V1. Accordingly, the second pump P2 supplies the operation fluid only to the first phase control unit U1 provided at the intake side camshaft 12a of the left side bank Eb1 through the first control valve V1. The second pump P2 is designed to have a proper ejection amount according to the viscosity of the operation fluid at the possible lowest temperature at the start of the engine. The temperature of the operation fluid can be set to, for example, −25° C. To meet with such high viscosity of the operation fluid, the rotation of the output shaft of the motor M can be reduced to rotate the rotor with a large torque and with a low rotation speed. The clearance between the rotor and the housing can be set to be large. Thus the operation fluid can be supplied to the first phase control unit U1 even when the operation fluid has a high viscosity at the low temperature when the engine is started.
The bypass passage 63 is provided in the hydraulic circuit O in parallel with the second pump P2 for communication between the upstream side and the downstream side of the second pump P2. A check valve 63a (one way valve) is provided in the bypass passage 63 to prevent an inadvertent reverse flow of the ejected operation fluid from the second pump P2 to the reservoir tank side through the bypass passage during the second pump P2 being operated. The operation fluid ejected from the first pump P1 is supplied to the first control valve V1 via the reservoir tank R and the bypass passage 63 when the first pump P1 is operated.
The reservoir tank R is provided between the first pump P1 and the second pump P2 for reserving a constant amount of fluid in a reservoir chamber Ra. The reservoir tank R includes a first communication port Rb for connecting the reservoir chamber Ra to the downstream side of the first pump P1, a second communication port Rc provided at the lower level than the first communication port Rb and connecting the reservoir chamber Ra to the upstream side of the second pump P2 and a lubrication system port Rd provided at the higher level than the first communication port Rb for connecting the reservoir chamber Ra to the engine lubrication system EL. The amount of reserved fluid in the reservoir chamber Ra includes a range lower than the location of the first communication port Rb and higher than the position of the second communication port Rc. The reservoir chamber reserves the fluid amount more than the amount necessary for supplying the operation fluid to the first phase control unit U1 from the second pump P2 under the first pump P1 being stopped condition. According to the embodiment, the second pump P2 supplies the operation fluid to the phase control mechanism N of the first phase control unit U1 under the first pump P1 being stopped and the ejection amount being insufficient. Accordingly, the required reserving amount of operation fluid in the reservoir chamber Ra of the reservoir tank R can be reduced by shortening the fluid flow passage between the second pump P2 and the first phase control unit U1 by arranging the second pump P2 close to the location of the first phase control unit U1.
The engine lubrication system EL, with which the lubrication system port Rd of the reservoir tank R, is exposed to the atmosphere and includes a flow resistance against the operation fluid flow. It is desirable to set the flow resistance of the lubrication system EL such that the operation fluid ejected from the first pump P1 is filled in the reservoir chamber Ra and a sufficient fluid pressure can be supplied to the hydraulic chamber 4 via the bypass passage 63 when the first pump P1 is operated and the second pump P2 is not operated. For example, when the second pump P2 is not operated and that the engine E is running with 200 rpm, the flow resistance in the reservoir chamber Ra is preferably the pressure level of 100 to 400 kPa. The lubrication system EL includes the main gallery portion of the engine E, chain tensioner portion and the piston jet portion.
The first pump P1 is stopped or the ejected amount of the operation fluid is not sufficient to be operated when the engine is just started. In such condition, the second pump P2 is operated to supply the operation fluid to the phase control mechanism N of the first phase control unit U1 as shown in
On the other hand, after the engine has started and the rotational speed (rpm) has risen, sufficient amount of operation fluid is ejected from the first pump P1. As shown in
As the first and the second control valves V1 and V2, a variable electromagnetic spool valve can be used. A spool of the valve is slidably disposed in a sleeve and is displaced by overcoming the force of spring when the solenoid is excited by the control device ECU. The first control valve V1 includes an advance angle port in communication with the advance angle passage 43, a retard angle port in communication with the retard angle passage 44, a supply port in communication with the flow passage at downstream of the second pump P2 and a drain port in communication with an oil pan 61. The second control valve V2 includes an advance angle port in communication with the advance angle passage 43, a retard angle port in communication with the retard angle passage 44, a supply port in communication with the flow passage at downstream of the first pump P1 and a drain port in communication with the oil pan 61. The first and the second control valves V1 and V2 form the three position control valve which enables the three position control consisting of an advance angle control by connecting the advance angle port with the supply port and connecting the retard angle port with the drain port, a retard angle control by connecting the retard angle port with the supply port and connecting the advance angle port with the drain port and a hold control by closing the advance angle port and the retard angle port. The first valve V1 and the second valve V2 respectively form the first phase control unit U1 and the second phase control unit U2 under the control of the control device ECU. Thus, the first and the second valves V1 and V2 perform the switching over operation of the lock mechanism 5 between the lock condition and the released condition (unlocked condition) and the controlling of the relative rotational phase between the inner rotor 3 and the outer rotor 2 (phase of intake side camshaft 12a).
The control device ECU operates the second pump P2 and the first and the second valves V1 and V2. In detail, the ECU controls motor rotational speed and/or rotational torque for driving the second pump P2 and controls position of the spool of the first and the second valves V1 and V2. The ECU controls the second pump P2 to supply operation fluid from the cranking starting to the completion of the combustion at the engine starting. According to the embodiment, the control device ECU supplies operation fluid by operating the second pump P2 when the temperature of the fluid is less than or equal to the predetermined threshold value (for example, −10° C.) based on the temperature detection signal from the fluid temperature sensor SO which detects the temperature of the operation fluid to be supplied to the phase control unit U. In this embodiment, the sensor SO is structured to detect the fluid (oil) temperature in the oil pan 61. However, the temperature of the fluid may be detected at any position in the flow path. The control device ECU in this embodiment controls the first and the second valves V1 and V2 such that the phase of the first phase control unit U1 becomes the same phase of the second phase control unit U2.
The operation of the valve timing control device 1 at the time of engine start based on the flowchart in
First, when the engine is not operated, the first and the second pumps P1 and P2 are not operated. The relative phase of the first and the second phase control units U1 and U2 is in lock phase condition (most retarded angle phase) and the lock member 53 of the lock mechanism 5 is projected to have the system in locked position. As shown in this embodiment, the lock phase is set to a phase near the boundary of the retard side for engine starting (9° C. in retard side relative to the intake lower dead point). Accordingly, when the temperature of the engine E is relatively low, it would be difficult to start (complete combustion) even if the cranking is performed under the rotation phase of the first and the second phase control units U1 and U2 being in locked position. Under the lock phase (phase being locked condition), the intake side camshaft 12a positions farther retarded side than normal position and the valve closing timing of the intake valve 13b is retarded as shown in
When the cranking for starting the engine E, the control device ECU operates the second pump P2 (second pump ON) to start and at the same time the first and the second valves V1 and V2 become the advance angle control condition which enables to supply operation fluid to the advance angle chamber 41 of the phase control unit U and the engagement recess 51 of the lock mechanism 5. In the first phase control unit U1, the lock mechanism 5 becomes unlocking condition (as shown in
On the other hand, since the first pump P1 driven by the engine E has a low rotational speed (rpm) and insufficient ejection amount, not sufficient amount of operation fluid is supplied to the second phase control unit U2 and the second control valve V2 both of which do not receive any fluid supply from the second pump P2. Accordingly, the second phase control unit U2 is kept to be in locking condition to keep the relative rotational phase being bound to the lock phase (most retarded angle phase) even after the second valve V2 is shifted to the advanced angle condition. In the right bank Eb2 where the second phase control unit U2 is located, the intake side camshaft 12a is kept to the most retarded angle phase position during engine cranking operation. The cylinder of the right side bank Eb2 is kept to the decompression condition having smaller resistance by the piston Ep (
After the combustion completed in the left side bank Eb1 the engine rotation speed raises and the ejection amount of the operation fluid from the first pump P1 increases. Accordingly, the lock mechanism 5 in the second phase control unit U2 becomes unlocked condition to shift the relative rotational phase in the advance angle side. This will shift the phase of the intake side crankshaft 12a to the advance angle side from the most retarded angle side in the right side bank Eb2 and the engine is completely combusted in the right side bank Eb2 at any phase timing. On the other side, the second pump P2 is stopped its operation after the sufficient amount of ejected operation fluid is obtained by the first pump P1 by the increase of the engine rotation speed in the left side bank Eb1 by complete combustion. After the complete combustion in the right side bank Eb2, the control device ECU controls the first and the second valves V1 and V2 so that the relative rotational phase of the second phase control unit U2 becomes the same phase with the first phase control unit U1. After the both phases become identical or the same the control device ECU controls the first and the second valves V1 and V2 to shift the phases at any desired position in response to the engine operation condition by keeping the phases of the intake side camshafts 12a, 12a of both left side and right side banks EB1 and Eb2 to the same phase position. By controlling the valve timing control device 1, the engine can be quickly and assuredly started (complete combustion) even the engine type is the one that supplies operation fluid only to one of the phase control units of one bank (in this embodiment in the left side bank Eb1) by the electrically operated second pump P2.
The previous embodiment shows a phase control unit U at intake side camshaft 12a of the engine and no phase control unit is provided at exhaust side camshaft 12b. However the invention is not limited to this structure and another set of phase control unit can be provided at the exhaust side camshaft 12b.
According to the previous embodiment, the hydraulic circuit O includes a reservoir tank R provided in a flow passage between the first and the second pumps P1 and P2. However, the invention is not limited to this structure, for example, there is no reservoir tank between the pumps but instead the first and the second pumps may be provided in parallel to each other and the operation fluid may be supplied to the first valve from the respective pumps. For example, the second pump P2 suctions operation fluid directly from the oil pan 61 and the fluid passage at downstream of the first pump P1 is connected to the flow passage at the downstream of the second pump and upstream of the first control valve V1. The second pump P2 driven by the motor M can be placed in the vicinity of the intake side camshaft 12a in one of the engine banks and accordingly, the flow path from the second pump P2 to the phase control unit U can be shortened to restrain the ejection resistance from the second pump P2. This can minimize the size and quantity of the second pump and the motor.
According to the previous embodiment, the lock phase of the phase control unit U by the lock mechanism 5 is explained as the most retarded angle phase but the lock phase position can be chosen to any phase position other than the most retarded angle position as long as the relative rotational phase between the inner and outer rotors can be shifted.
The previous embodiment explains about the structure having the phase control unit U, which sets the locked phase for holding the intake side camshaft 12a to a phase, located at the vicinity of boundary of the retarded side. This setting in one of the examples of the invention and is not limited to this structure. The setting may be decided depending on the engine type and use conditions. It is preferable to set the lock phase at a retarded side a predetermined angle more than the intake lower dead point of the valve timing of the intake valve 12a. This setting can reduce the engine vibration by performing the decompression condition during the engine cranking.
According to the previous embodiment, the second pump is operated only when the temperature of the operation fluid is less than or equal to a predetermined temperature. However, it is possible to operate the second pump regardless of the temperature of the operation fluid.
The valve timing control device 1 is applied to the DOHC type engine in the previous embodiment. However, the invention can apply to the SOHC type engine. Also the invention can be applied to horizontally opposed type, W-type in addition to the V-type engine as long as the engine has a plural set of camshafts.
The principles, preferred embodiment and mode of operation of the present invention have been described in the foregoing specification. However, the invention is not to be construed as limited to the particular embodiment disclosed. Further, the embodiment described herein is to be regarded as illustrative rather than restrictive. Others may make variations and changes, and equivalents employed, without departing from the spirit of the present invention. Accordingly, it is expressly intended that all such variations, changes and equivalents that fall within the spirit and scope of the present invention as defined in the claims, be embraced thereby.
Number | Date | Country | Kind |
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2006-123303 | Apr 2006 | JP | national |