Abstract:
A valve timing phaseshifter between two members, such as a crankshaft driven housing and a driven camshaft member, that are hydraulically interconnected by fluid trapped in hydraulic cylinders containing plungers connected to the camshaft, relative movement between the cylinders and plungers providing the phaseshifting and being controlled by a valve that is axially movably mounted within the camshaft and hydraulically connected thereto by sets of helical grooves that are aligned or misaligned as a function of axial movement of the valve in response to the call for phase adjustment, the valve being movable from a neutral position to other positions in opposite directions to control the flow of fluid under pressure to the cylinders to cause the drive and driven members to rotate unitarily or for the camshaft to be advanced or retarded as the case may be, with respect to a conventional timing schedule.

Description:
FIELD OF THE INVENTION 
     This invention relates in general to an automotive engine timing system. More particularly, it relates to a mechanism for phaseshifting one engine component relative to another, such as, for example, a camshaft relative to the engine crankshaft. 
     BACKGROUND OF THE INVENTION 
     Most commercially available automotive engines use fixed lift and duration valve timing events. As a result, there is a compromise between the best fuel economy, emission control, and engine power conditions. 
     Potentially better fuel economy, emission control, and other engine output benefits can be realized if the timing of these events can be varied depending on the engine operating mode. 
     This invention is directed to several embodiments of a phaseshifting mechanism changing the engine timing from a conventional schedule to accomplish the above objectives. The mechanism comprises a driving member and a member driven thereby hydraulically through a fluid to effect relative rotation between the two at times to change the phasing, a unique valve construction with helical grooving fluid connecting the valve with the driven member controlling the hydraulic operation. 
     DESCRIPTION OF THE PRIOR ART 
     Phaseshifters in general are known in the prior art. U.S. Pat. No. 4,858,572, Shirai et al., describes and shows an angular vane type phase adjuster between the engine crankshaft 15, 16 and camshaft 11 utilizing oil pump pressure on opposite sides of the vanes in the chambers to angularly rotate the camshaft. A solenoid actuated, spring returned slide valve is used to control direction of oil flow. 
     There is no use of the movement of a helically grooved valve to control movement of a plunger in a pressure balanced chamber, nor is there a return of the vane to a new neutral position after each movement. 
     U.S. Pat. No. 5,002,023 and U.S. Pat. No. 5,046,460, Butterfield et al., both show and describe a dual camshaft, self actuating phaseshifter in which a crankshaft driven member and a camshaft are interconnected by a hydraulic system including hydraulic cylinders containing oppositely moving plungers that automatically react to the engine&#39;s torque pulses to advance or retard the timing. When one extends in one direction, the other retracts in the opposite direction. The plungers are movable in bores in the crankshaft driven housing, as controlled by oil pressure controlled by a spool valve 92 (FIG. 12). The valve can be moved by fluid pressure from one spring biased position to either a neutral position or another active position. The valve movement is controlled as a function of an engine parameter controlled computer. 
     The plungers move at right angles to the camshaft axis so as to rotate the camshaft upon movement of the plungers. The plungers do not operate in balanced pressure fluid chambers, and are not controlled by a hydraulic system utilizing a helically grooved valve connected to the crankshaft for rotation therewith and hydraulically connected to the camshaft to control the plunger movement and return to a new neutral position after each phase change movement. 
     U.S. Pat. No. 4,903,650, Ohlendorf et al., shows and describes a rotary vane type angular Phase adjuster between a crankshaft driven sprocket wheel 1 and a camshaft 7. An axial bore contains a slidable, spring returned valve/plunger 13 actuated by an electromagnet 18 to control flow of oil to or from fluid chambers on opposite sides of the vane 9. The control system does not utilize a valve and camshaft with helical grooves and a pressure balanced/unbalanced fluid chamber to effect movement of the plunger/vane and return to a new neutral position after each movement to be ready for advance or retard from the new position. 
     Many of the prior art references effect relative Phase adjustment movement by the use of helical splines/straight splines sets directly between the members, and a fluid control system, but not one using a valve having helical grooves between the driven member and the valve to control fluid flow in the unique manner to be proposed. 
     For example, U.S. Pat No. 4,895,113, Speier et al., shows and describes an angular phaseshifter between a crankshaft driven sprocket wheel 3 and a camshaft 11. An annular piston 6 is helically splined between the sprocket 3 and camshaft and axially movable to change the angular relation between the two by admitting fluid to and draining fluid from opposite chambers/sides of the piston. A spring biased control piston 17 is located in an axial bore and moved against the bias by an electromagnet 22 to supply oil pressure to one side of the piston to advance the camshaft, oil draining to the sump from the other side of the Piston. Turning off the electromagnet returns the valve 17 to its base camshaft retarded position. In this case, the helical grooves, per se, effect the angular movement. No valve with helical grooves controls a hydraulic circuit to a plunger to move the camshaft. The helical teeth provide the movement, not the valve controlling movement of the plunger/cylinder. 
     U.S Pat. No. 4,787,345 Thoma, describes and shows a phase adjusting mechanism between a crankshaft driven member 6 and a camshaft 1. The two are interconnected for relative angular rotation through the agency of helical and straight splines between. A piston 23 is movable to effect the angular displacement, the piston movement being controlled by pressure fluid controlled by a valve 51. 
     U.S. Pat. No. 4,601,266, Oldfield et al., shows and describes a phase adjuster in which a crankshaft driven member 21 is helically splined to a driven camshaft member 26 by a cam 89. A piston 20 is infinitely variably movable in opposite directions by engine oil pressure to effect the angular rotation of one member relative to the other. Solonoid operated valves provide a lock of the piston in a particular position. The relative rotation is effected by helically forcing axial movement, not by hydraulic pressure. 
     U.S. Pat. No. 5,090,365, Hotta et al., shows and describes a phaseshifter wherein a crankshaft driven member and camshaft are interconnected helically and angularly rotated relative to one another by axial movement of a piston under oil pressure. 
     U.S. Pat. No. 5,088,456, Suga, shows and describes a camshaft 1, and a crankshaft driven member 8 with spiral gear teeth moved by oil pressure to effect angular rotation between the crankshaft and camshaft. 
     SUMMARY OF THE INVENTION 
     The invention relates to a valve timing phaseshifter consisting of a driving member such as a crankshaft driven housing and a driven member such as a camshaft, that are hydraulically interconnected by fluid trapped in hydraulic cylinders containing plungers connected to the camshaft; relative movement between the cylinders and plungers providing the phaseshifting and being controlled by a valve that is axially movably mounted within the camshaft and hydraulically connected thereto by sets of helical grooves that are aligned or misaligned as a function of axial movement of the valve in response to the call for phase adjustment, the valve being movable from a neutral position to other positions in opposite directions to control the flow of fluid under pressure to the cylinders to cause the drive and driven members to rotate unitarily or for the camshaft to be advanced or retarded as the case may be, with respect to a conventional timing schedule. 
     It is, therefore, a primary object of the invention to provide an automotive timing system with a phase adjusting mechanism that will phaseshift a pair of rotating components by means of a hydraulic system that hydraulically interconnects the two in a manner controlled by a valve mechanism, the latter being fluid connected to one of the members by sets of helical grooves in the valve and member, the valve being axially movable to and from a neutral position to control a supply of fluid under pressure to cause the phase change to be effected when desired. 
     Other objects, advantages and features of the invention will become more apparent upon reference to the succeeding, detailed description thereof, and to the drawings illustrating the preferred embodiments thereof. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional view of a portion of an automotive type engine embodying the invention. 
     FIG. 2 is a cross-sectional view taken on a plane indicated by and viewed in the direction of the arrows II--II of FIG. 1. 
     FIGS. 3, 4, and 5 are diagrammatic representations of three different hydraulic control systems embodying the invention. 
     FIG. 6 is a cross-sectional view of a further embodiment of the invention. 
     FIG. 7 is a cross-sectional view taken on a plane indicated by and viewed in the direction of the arrows VII--VII of FIG. 6. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows a phaseshifter consisting of two main bodies, a crankshaft driven annular housing 12, and a camshaft 14. The engine crankshaft (not shown) could be connected to housing 12 by means of a sprocket wheel (not shown), or by any other suitable means. 
     The housing has a central bore 16 that rotatably receives within it the tubular camshaft 14. The camshaft has a vertical flange 18 that extends radially from the shaft, the flange mounting a pair of pins 20 at right angles to it. A pair of cylindrical bores 21 are machined in the housing and located symmetrically on opposite sides of the housing axis, a plunger 22, 23 being installed in each. The open ends of the bores are closed by plugs 24, 26 to define hydraulic cylindrical chambers 28 and 30 between the plunger and the plugs, all four chambers being filled with oil. 
     The pins 20 are fixed to the plungers as shown in FIGS. 1 and 2 by protruding through slots 32, 34 in the housing 12 and plunger 22. As seen in FIG. 1, the slot 32 in the housing is elongated or oval shaped to permit a limited lateral relative movement between the plunger and the housing. The engagement of the pin to the plunger is such that any axial movement of a plunger in its bore causes a concurrent rotation of the flanged shaft 14 relative to the housing 12. 
     The tubular or sleeve-like camshaft 14 is adapted to receive within its hollow interior 35 a cylindrical slide valve 36. The valve has a stepped diameter body 37, with two sets of helical grooves 38, 40, 42, 44, and 46, 48, 50, 52 machined on its outer surface (FIG. 3). The grooves are adapted to mate or be aligned or misaligned at times with two corresponding sets of helical grooves 54, 56, 58, and 60, 62, 64 machined in the inner wall of the camshaft 14. 
     The valve 36 is mounted for an axial movement within the camshaft, with the smaller diameter body portion 66 projecting sealingly through an opening 68 in the camshaft end wall, as shown. A spring 70, seated between the valve and wall of the camshaft, biases the valve to the left, in a timing retard direction, as will become more clear later. The opposite end of the valve abuts the end of a pushrod 72 that is part of a separate control mechanism, not shown. Selective movement of the pushrod will move the valve 36 to the right against the force of spring 70 in a timing advance direction, as indicated in FIG. 3, for example. 
     The control valve 36 rotates in unison with the housing 12 by means of a pin 74 that is press fitted into the hub of the housing. It passes through elongated holes 76 (FIG. 3) in the camshaft 14, and engages the valve through a slot 78 that permits axial displacement of the valve. 
     Oil, supplied by an outside pump, flows through internal passages in the phaseshifter, indicated partially at 80 (FIG. 1) in the valve end, and returns to the sump, which often is the engine crankcase. The valve can be moved in opposite directions from a neutral position to a retard position or to an advance position, as indicated previously, to effect a corresponding movement of the plunger to advance or retard the engine timing. 
     FIG. 3 illustrates diagrammatically the hydraulic connections in the phaseshifter. In FIG. 3, for clarity, the axis of plunger 22 is shown in the same plane as the axis of valve 36; in reality, the axes of the plunger and the valve are in perpendicular planes, as shown in FIG. 1. 
     The corresponding sets of internal and external helical grooves 38-44 and 54-58 are part of a hydraulic circuit controlling the position of the plunger 22 in its bore. The other set of internal and external helical grooves 46-52 and 60-64 is part of a circuit controlling the second plunger 23 (FIG. 2), which is not shown as the operation is identical. The hydraulic connections are arranged so that the hydraulic forces acting on the two plungers 22, 23 form a force couple about the valve axis indicated in FIG. 1. 
     FIG. 3 indicates the control valve 36 in a neutral position. Grooves 54 and 58 are connected through camshaft passages 90 and 92 and lines 94 and 96 to the end chambers 28 and 30. Grooves 40 and 44 are connected to each other through camshaft passages 98 and 100 and a line 102. Line 102 contains a one-way check valve 104, for a purpose to be described later. Grooves 38 and 56 are connected to the engine oil sump through a pair of passages 84 and 86 in camshaft 14, and a return line 88. Oil under pressure from a pump, such as the engine oil pump, is supplied through an inlet line 105 and a camshaft inlet passage 106 to the groove 42. Grooves 42 and 56 are directly connected so that oil delivered to groove 42 flows through groove 56 back into the sump. The grooves 54 and 58 are blocked and remain isolated from the rest of the circuit so that the oil in chambers 28 and 30 is trapped there 
     When the pushrod 72 is activated in response to predetermined engine parameters to move the valve 36 to the right to advance the timing, the passage between grooves 42 and 56 is drastically reduced, throttling the oil flow and increasing the pressure in the groove 42. At the same time, groove 42 becomes connected to groove 58, and groove 38 becomes connected to groove 54. As a result, pressurized oil is delivered through grooves 42 and 58 to the chamber 30, forcing the plunger 22 to move in the direction of rotation. The oil previously trapped in chamber 28 flows out through the grooves 54 and 38 to the sump. The motion of the plunger 22 is transmitted through pin 20 to the camshaft 14, which advances relative to the housing 12 and relative to the valve 36. Since the grooves on the valve 36 and in the camshaft 14 are helical, rotation of the camshaft 14 relative to valve 36 has an effect similar to that as if valve 36 is subjected to axial displacement. The angular motion of camshaft 14 and the grooves 54, 56 and 58 relative to the valve 36 and the grooves 38, 40, 42, and 44 in the direction of overall rotation indicated, now opens the passage between the grooves 42 and 56 and isolates the grooves 54 and 58. Therefore, a new neutral position of the valve 36 is reached, and the advance motion of the camshaft 14 stops. The angle of advance of the camshaft 14 relative to the housing 12 is proportional to the axial displacement of the valve 36 in the direction of advance to the right. 
     When the valve 36 is moved to the left, groove 54 becomes connected to groove 40 and the groove 58 becomes connected to the groove 44. As a result, the chambers 28 and 30 become connected and, since for the given direction of rotation and the mean driving torque, the mean pressure in the chamber 30 is higher than in the chamber 28, oil flows from the chamber 30 to the chamber 28. The plunger 22 moves in the direction opposite to the direction of rotation and its motion is transmitted through the pin 20 to the camshaft 14 which lags in its rotation behind the housing 12 and the valve 36. The relative angular motion of the camshaft 14 relative to the valve 36 in the direction opposite to the direction of overall rotation isolates the grooves 54 and 58 from the grooves 40 and 44, respectively. A new neutral position of the valve 36 then is reached, and the retard motion of the shaft 12 stops. The angle of retard of the camshaft 14 relative to the housing 12 is proportional to the axial displacement of the valve 36 in the direction of retard to the left. 
     During engine operation, the camshaft 14 is subjected to a continuous series of reaction torque pulses of alternating direction, which are associated with opening and closing of the engine valves. During the engine valve opening, the reaction torque is directed against the direction of rotation and leads to increased pressure in the chamber 30. During the engine valve closing, the direction of the reaction torque coincides with the direction of rotation, and leads to increased pressure in chamber 28. When the valve 36 is moved to the left and the chambers 28 and 30 become connected, oil flows from the chamber 30 to the chamber 28 during engine valve opening and can also flow back from the chamber 28 to the chamber 30 during engine valve closing. Since the magnitude of the torque directed against the rotation is larger than that directed with rotation, the net flow is from the chamber 30 to chamber 28 and the camshaft 14 is retarded, but the intermittent reversals of oil flow slow down the response of the device. To improve the response, the check valve 104, indicated in dotted lines, can be incorporated in the passage connecting the grooves 40 and 44 in FIG. 3. The check valve permits oil to flow from the chamber 30 to chamber 28 but prevents reverse flow in the opposite direction. 
     It should be noted that the above described system is inherently self-adjusting and self-compensating. Any inadvertent and unintended phaseshift of the camshaft 14 relative to the housing 12 would be automatically corrected by hydraulic action and the original Phase relation would be restored without need to adjust the position of the valve 36. Such inadvertent phaseshift is most likely to be a retard of the camshaft 14 due to internal leakage from and between the chambers 28 and 30. Such a retard of the camshaft 14 relative to the valve 36 creates conditions equivalent to those which exist when the valve 36 is moved to the right. This, in turn, causes the camshaft 14 to advance until the previous phase relation is restored. Each axial position of the valve 36 determines a specific phase relation between the housing 12 and the camshaft 14 which is automatically maintained by the hydraulic system. 
     It should also be noted that, in the above system, input of energy needed to perform the phaseshift is required only during the phaseshift towards advance when fluid under pressure effects the move. No energy input is needed to perform the retard because the two chambers are interconnected with the supply source blocked off, thereby eliminating the need for a pressure source buildup. Likewise, no energy is consumed at steady state conditions between the phaseshifts when again the supply source is returned to sump. 
     FIG. 4 illustrates an alternative embodiment of the phaseshifter. In this case, the set of short external helical grooves on each side of the valve 36 consists of only three grooves 120, 122, and 124, and the corresponding set of internal grooves in the camshaft 14 consists of two grooves 126 and 128. Oil pressure is supplied to groove 122 from an external hydraulic circuit. Such pressure can be generated in the external circuit by various means, such as for example, by a pump pumping oil through a pressure regulating valve. Grooves 120 and 124 are connected to the return to sump line indicated. Grooves 126 and 128 are connected to the chambers 28 and 30, respectively. The valve 36 is shown in neutral position. In this position, the grooves 126 and 128 remain isolated from the grooves 120, 122 and 124, and the oil in the chambers 28 and 30 is trapped therein. 
     When the valve 36 is moved to the right to advance the timing, groove 122 becomes connected to groove 128, and groove 120 is connected to groove 126. As a result, Pressurized oil is delivered through grooves 122 and 128 and the lines indicated to the chamber 30, forcing the plunger 22 to move in the direction of rotation, while the oil previously trapped in the chamber 28 flows out through the grooves 126 and 120 to the sump. The remaining action is similar to what was described before, and the camshaft advances relative to the housing 12 until a new neutral position of the valve 36 is reached. 
     When the valve 36 is moved to the left, groove 122 becomes connected to groove 126, and groove 124 is connected to groove 128. As a result, pressurized oil is delivered through grooves 122 and 126 to the chamber 28, forcing the plunger 22 to move counter to the direction of rotation, while the oil previously trapped in the chamber 30 flows out through grooves 128 and 124 to sump. The camshaft 14 lags behind the housing 12 until a new neutral position of the valve 36 is reached. This operation differs from that previously described in that the retard motion is performed under the force of the Pressurized oil instead of engine reaction torque pressurizing chamber 30. 
     FIG. 5 shows still another modification of the phaseshifter. In this case, the set of short external helical grooves on each side of the valve 36 consists of six grooves, 140, 142, 144, 146, 148, and 150; and the corresponding set of internal grooves in the camshaft 14 consists of four grooves 152, 154, 156, and 158. As it was the case in the diagram in FIG. 3, oil is supplied by an outside pump, flows through the phaseshifter and returns to the sump. In any neutral position there is no need to increase the oil pressure. 
     Oil supplied by the pump is delivered to the grooves 152 and 158. Grooves 154 and 156 are connected to the return to sump line. Grooves 142 and 148 are connected to the chambers 28 and 30, respectively. Groove 140 is connected with groove 144, and groove 146 is connected with groove 150. The valve 36 is shown in neutral position, wherein the groove 142 remains isolated from the grooves 152 and 154. The groove 148 is isolated from the grooves 156 and 158; and, therefore, the oil in the chambers 28 and 30 is trapped therein. 
     When the valve 36 is moved to the right, the passages between the grooves 144 and 154 and between the grooves 150 and 158 are reduced, throttling the oil flow and increasing the pressure in the groove 158 which becomes connected to groove 148. As a result, pressurized oil is delivered through the grooves 158 and 148 to the chamber 30, forcing the plunger 22 to move in the direction of rotation while the oil previously trapped in the chamber 28 flows out through the grooves 142 and 154. The remaining action is again similar to that previously described, and the camshaft 14 advances relative to the housing 12 until a new neutral position of the valve 36 is reached. 
     When the valve 36 is moved to the left, the passages between the grooves 140 and 152, and between grooves 146 and 156, are reduced, throttling the oil flow and increasing the pressure in the groove 152 which becomes connected to the groove 142. At the same time, the groove 148 becomes connected to the groove 156. As a result, pressurized oil is delivered through the grooves 152 and 142 to the chamber 28 forcing the plunger 22 to move in the direction opposite to the direction of rotation, while the oil previously trapped in the chamber 30 flows out through the grooves 148 and 156. The camshaft 14 is retarded relative to the housing 12 until a new neutral position of the valve is reached. 
     The concept illustrated in FIG. 5 is similar to that of FIG. 4 in that both the advance and retard motions are performed with the use of pressurized oil. However, unlike the concept of FIG. 4, it does not require a continuous supply of prepressurized oil because, like the FIG. 2 construction, oil Pressurization takes place only during advance or retard movements, and there is no hydraulic energy consumption between the phaseshifts. The oil is circulated back to the sump under these conditions without a pressure buildup. 
     From the foregoing, it will be seen that the invention provides a number of phaseshifting concepts utilizing a valve axially movable within one member and being rotatable with another member, and hydraulically interconnecting the two by means of sets of helical grooves matingly arranged to supply fluid under pressure at times to hydraulic cylinders containing movable Plungers trapped therein as a function of the movement of the valve. 
     While the invention has been shown and described in its preferred embodiments, it will be clear to those skilled in the arts to which it pertains, that many changes and modifications may be made thereto without departing from the scope of the invention. For example, in all of the above described concepts, the valve 36 was moved to the right for advance and to the left for retard. This was the result of the selection of right-handed helical grooves. It will be clear that the direction of the valve motions could be reversed, if the hand of the helix is changed. 
     Also, while the described mechanisms used only two plungers 22, 23 each. Three or even more could be used without departing from the scope of the invention. Still further, while plungers were described and shown, vanes, pistons, diaphragms and other similar devices capable of transmitting motion and force through hydraulic fluid, could be used. For example, FIGS. 6 and 7 show an alternate design that uses vanes 180 instead of plungers. However, the remaining construction and operation are the same as described in connection with FIGS. 1-5, the hydraulic chambers 182 and 184 formed between each side of a vane and the housing performing essentially the same function as the chambers 28 and 30 formed by each end of a plunger and the Plunger housing.