JP2005264950A - Method for controlling liquid-pressure fluid flowing from its source to means for conveyance to camshaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for controlling a liquid-pressure fluid flowing from its source to precisely and surely change the phase angle of the camshaft to the crankshaft. <P>SOLUTION: The intended objective is attained by detecting the position of a camshaft and a crankshaft, by issuing electric signals corresponding to the stated phase angle through an engine control unit, and by controlling the position of a spool for exhausting pressure from within a cave in the spool valve, which is so arranged as to be able to slide within the main body of the spool valve; with this control carried out by utilizing an electric machinery-type actuator equipped with a force-variable solenoid to change the position of the spool having the aforementioned exhaust port, by making the aforementioned spool valve allow or prevent inflow of the liquid-pressure fluid into aforementioned housing through the entry line and return line, and by controlling the position of the spool in the spool valve. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

Industrial application fields

  The present invention relates to the operation of a variable camshaft timing (VCT) device of the type in which the camshaft position is changed in the circumferential direction with respect to the crankshaft position in response to the reversal of torque that the camshaft receives during normal operation The present invention relates to a hydraulic pressure control device for controlling the pressure. In such a variable camshaft timing device (hereinafter referred to as a VCT device), the hydraulic device is provided to reposition the crankshaft in response to such torque reversal, and the control device is the hydraulic device. Is provided to selectively allow or prevent such repositioning.

  More particularly, the present invention relates to a control device using a variable force solenoid that directly controls the position of a fully drained holed spool valve, which is a useful part of a hydraulic device.

Conventional technology

A discussion of the information presented in the following US patents, incorporated herein by reference, is useful when investigating the background of the present invention.
U.S. Pat. No. 5,002,023 describes a VCT device belonging to the field of the invention, in which the hydraulic device is provided with a pair of oppositely acting hydraulic cylinders and suitable hydraulic flow. The element selectively sends hydraulic fluid from one hydraulic cylinder to the other hydraulic cylinder or vice versa, thereby advancing or retarding the circumferential position of the camshaft relative to the crankshaft. The control device utilizes a control valve in which the discharge of hydraulic fluid from one or the other of the counteracting cylinders causes the spool in the control valve to move from a central or null position to one or the other. Done by moving. The movement of the spool is between the increase or decrease of the control hydraulic pressure Pc at one end of the spool and the opposite mechanical force at the other end due to the hydraulic pressure at that end and the acting compression spring. Happens in response to the relationship.

  U.S. Pat. No. 5,107,804 describes another type of VCT device belonging to the field of the invention, wherein the hydraulic device comprises a vane having a lobe in a closed housing, the lobe. Replaces the counteracting cylinder shown in the aforementioned US Pat. No. 5,002,023. The vane is swingable with respect to the housing, and a suitable hydraulic flow element sends hydraulic fluid in the housing from one side of the lobe to the other or vice versa, thereby causing the vane to move in one direction relative to the housing. The other side is controlled so as to move the camshaft forward or backward with respect to the crankshaft. The controller of this VCT device is the same as that shown in the above-mentioned US Pat. No. 5,002,023, and uses the same type of spool valve that responds to the same acting force.

  U.S. Pat. Nos. 5,172,659 and 5,184,578 are both described above, made to balance the hydraulic pressure acting on one end of the spool with the mechanical force acting on the other end. It deals with VCT equipment issues. The improved control system shown in both US Pat. Nos. 5,172,659 and 5,184,578 utilizes hydraulic pressure acting on both ends of the spool. The hydraulic pressure at one end is due to the hydraulic fluid applied directly from the engine sump at the total hydraulic pressure Ps. The hydraulic pressure acting on the other end of the spool is attributed to a hydraulic cylinder or other force amplifier, which acts in response to the low pressure Pc system hydraulic fluid from the PWM solenoid. Since the force at each end of the spool is essentially a hydraulic pressure based on the same hydraulic fluid, the change in pressure or velocity of the hydraulic fluid is self-negative, and the center position or zero of the spool Does not affect the position. However, the inventions shown in the aforementioned US Pat. Nos. 5,172,659 and 5,184,578 have several inherent disadvantages.

  One drawback is that the differential pressure controller (DPCS) cannot properly control the spool position during the initial start phase of the engine. When the engine is first started, it takes a few seconds for the hydraulic pressure to occur. Meanwhile, the position of the spool valve is not known. Since the system logic does not have a known amount to perform the necessary calculations, the DPCS cannot effectively control the position of the spool valve until the engine reaches normal operating speed.

  Another problem with existing VCT devices is that the dynamic response is slow. Even after the engine has stabilized at normal operating speeds, the individual characteristics vary considerably from engine to engine. New engines at high speeds and low temperatures can have oil pressures that are significantly different from worn-out engines in thick idle conditions. Existing methods adopted to operate over a wide range of engine characteristics (such as increased cross-sectional area of hydraulic pistons and smaller springs) result in lower response speed and stability Therefore, a relatively low closed-loop controller gain is required.

  The low closed-loop controller gain makes the device more susceptible to component tolerances and operating environments. The net effect (such as the change in PWM duty cycle required to achieve the center or null position of the spool) degrades the performance of the overall closed loop device.

  Finally, the moving parts of the PWM solenoids that are particularly used in normal DPCS generate unwanted noise in the device. In operation, the solenoid is repeatedly operated over its entire stroke with each PWM pulse. Rapid repetitive movement will cause the armature and poppet to rattle, i.e., generate high frequency vibrations, and thus generate undesirable noise.

  It is an object of the present invention to provide an improved method for controlling the operation of a hydraulic control valve with a drain hole or a drain spool.

  Another object of the present invention is to provide an improved method for controlling the operation of a spool type hydraulic control valve with a discharge hole in an automatic variable camshaft timing device.

The present invention also provides an internal combustion engine having a variable camshaft timing device that changes the phase angle of the camshaft relative to the crankshaft, in order to change the phase angle of the camshaft relative to the crankshaft. A hydraulic fluid from a fluid source to a means for transmitting to the camshaft via a housing rotatable with the camshaft and swingable with respect to the crankshaft and attached to the camshaft. In a method for controlling flow,
Detecting the positions of the camshaft and crankshaft;
Calculating a relative phase angle between the camshaft and the crankshaft, the calculating using an engine control unit for processing the information obtained from the detection and controlling the engine The unit emits an electrical signal corresponding to the phase angle;
Controlling the position of a spool slidably disposed within the spool valve body and relieving pressure in the cavity of the spool valve, wherein the controlling is responsive to the signal received from the engine control unit Using the electromechanical actuator having a force variable solenoid to change the position of the spool having the exhaust hole;
Supplying hydraulic fluid from the fluid source through the spool valve to the means for transmitting rotational motion from the crankshaft to the camshaft, the spool valve passing through an inlet line and a return line. Allowing and preventing hydraulic fluid flow into the housing;
Controlling the position of the spool to transmit rotational motion to the camshaft and selectively permit or block hydraulic fluid flow to change the camshaft phase angle relative to the crankshaft;
It is configured with.

  In the engine, the electromechanical actuator may include a force variable solenoid. The force variable solenoid includes a coil that receives a current from the engine control unit, an armature substantially surrounded by the coil, an air gap that separates the coil from the armature, the coil, the armature, and A housing that provides an enclosure for the air gap, and when the armature is connected to the spool and the coil is energized, the armature applies a force to the spool to move the spool. A sufficient magnetic field may be generated and the movement may correspond to the signal from the engine control unit. Further, the electromechanical actuator may further comprise a stroke amplifier, and the stroke amplifier may comprise a lever device when the stroke amplifier is applied to the drained spool, and the stroke amplifier may comprise a lever device. .

Action

  The present invention provides an improved method and apparatus for controlling the position of a vented or drained spool in a hydraulic control valve. More particularly, the present invention relates to a control control valve that is the same as the hydraulic control valve used in a hydraulic cylinder VCT device timing device acting opposite to the type shown, for example, in US Pat. No. 5,002,023. A method and apparatus for controlling the position of a spool with a discharge hole in a hydraulic control valve similar to the hydraulic control valve used in a vane type VCT timing device of the type shown in US Pat. No. 5,107,804 is provided. To do.

  The controller of the present invention removes the hydraulic pressure at one end of the spool due to the hydraulic fluid applied directly from the engine oil reservoir at the total hydraulic pressure PS used by the previous embodiment of the VCT apparatus. The force at the other end of the spool with the discharge hole is preferably due to an electromechanical actuator of variable force solenoid type, which force is an electronic signal issued from an engine control unit (ECU) that monitors various engine parameters. In response to this, it acts directly on the spool with the discharge hole. The ECU receives signals from sensors corresponding to the camshaft and crankshaft positions and uses this information to calculate the relative phase angle. The preferred embodiment employs a closed loop feedback device such as that shown in US Pat. No. 5,184,578, which corrects for any phase angle error. The present invention provides an effective and economical solution to the above-mentioned problems and additional advantages over conventional DPCS.

  When the relationship between spool position and control signal (solenoid current) is independent of engine oil pressure, any problems associated with oil pressure or variations thereof are also eliminated. For example, if normal operating oil pressure cannot be obtained during initial engine start, a signal from the ECU is immediately supplied to the solenoid that directly positions the spool, so that no start error occurs.

  Using a force variable solenoid solves the problem of slow dynamic response. Such a device can be designed to respond as fast as the mechanical response of a spool valve and is definitely faster than normal (full hydraulic) DPCS. A fast response allows the use of increased closed loop gain, making the device less sensitive to component tolerances and operating environments.

  The armature of the variable force solenoid is countered for the entire cycle by using the PWM solenoid, so it moves only a short distance when controlled by the current from the ECU. Since the required movement is rarely excessive, rattling is prevented and the device is almost no noise.

  Perhaps an important advantage over normal DPCS is improved control of the basic equipment. The present invention provides a great ability to quickly and accurately track VCT phase command inputs.

  Furthermore, since the preferred embodiment of the present invention does not rely on hydraulic pressure, the present invention can be used for applications where an oilless actuator such as that associated with a timing belt engine is desired.

  In an alternative embodiment, a lever device or equivalent is functionally disposed between the electromechanical actuator and the spool. The lever device works effectively as a stroke amplifier / force dampener, allowing a reduction in the required solenoid current or clearance distance without sacrificing valve movement.

Embodiments of the present invention will be described below with reference to the drawings.
In the example of FIGS. 1-9, a sprocket 24 is keyed to the crankshaft 22, and rotation of the crankshaft 22 during operation of the built-in engine, not shown, may result in an exhaust camshaft 26 or engine exhaust valve. Is transmitted to the camshaft used to operate the vehicle by a chain 28 applied to the sprocket 24 and a sprocket 30 keyed to the camshaft 26. Although not shown, a suitable chain tensioning device is provided to keep the chain 28 relatively taut so as not to loosen. As shown, the sprocket 30 is twice as large as the sprocket 24. Due to this relationship, the rotational speed of the camshaft 26 is ½ of the rotational speed of the crankshaft 22, which is suitable for a four-cycle engine. A belt can be used in place of the chain 28.

  The camshaft 26 supports another sprocket or sprocket 32 that swings over a limited arc with respect to the camshaft as shown in FIGS. 3, 4 and 6, or the camshaft. And is rotatably supported. The rotation of the camshaft 26 is transmitted to the intake camshaft 34 by the chain 36, and the chain is hung around the sprocket 32 and the sprocket 38 keyed to the intake camshaft 34. As shown, sprockets 32 and 38 are equal in diameter and provide equal rotational speed between camshaft 26 and camshaft 34. A belt may be used instead of the chain 36.

  As shown in FIG. 6, the end of each of the camshafts 26 and 34 is bearing for rotation within the bearings 42 and 44 of the head 50, respectively, the head being partially shown and a bolt 48. Bolted to engine block not shown by The opposite ends of camshafts 26 and 34 not shown are similarly supported to rotate to the opposite ends of head 50 not shown. The sprocket 38 is keyed to the cam shaft 34 at the position of the cam shaft 34 outside the head 50. Similarly, the sprockets 32 and 30 are arranged side by side with the camshaft 26 at a position outside the head 50, so that the sprocket 32 is laterally aligned with the sprocket 38 and the sprocket 30 is laterally aligned with the sprocket 24. Located slightly outside.

  The sprocket 32 has an arc-shaped retainer 52 (FIGS. 7 and 8) as an integral part, and the retainer 52 extends outward from the sprocket 32 through an arc-shaped opening 30 a of the sprocket 30. The sprocket 30 is bolted with an arcuate hydraulic device body 46, and the hydraulic device body 46, which houses several hydraulic components of the associated hydraulic control device, is a pair of oppositely acting units. The respective hydraulic cylinders 54 and 56 receive the respective body ends and are pivotally supported. The hydraulic cylinders are arranged on both sides of the longitudinal axis of the camshaft 26. The piston ends of the cylinders 54 and 56 are pivotally attached to an actuating bracket 58 that is secured to the sprocket 32 by a plurality of threaded stops 60. Thus, by extending one of the cylinders 54 and 56 and retracting the other of the cylinders 54 and 56 simultaneously, the working piston of the sprocket 32 is pushed with respect to the sprocket 30 and if the cylinder 54 is extended and the cylinder 56 is retracted. The sprocket 32 is advanced (this is the operating state shown in FIGS. 2 and 4) or is delayed with respect to the sprocket 30 if the cylinder 56 is extended and the cylinder 54 is retracted (this is illustrated in FIGS. 3 and the operation state shown in FIG. 7 and FIG. In either case, the position lag or advance of the sprocket 32 relative to the position of the sprocket 30 is responsive to the direction of torque on the camshaft 26 as described in the aforementioned US Pat. No. 5,002,023. A chain 36 between a sprocket 32 supported to limit relative arcuate movement on the camshaft and a sprocket 38 keyed to the camshaft 34, which is selectively allowed or prevented. The chain drive connection provided advances or delays the position of the camshaft 34 relative to the position of the camshaft 26. This relationship is shown in FIGS. 2 and 4 with respect to the relative position of the timing mark 30b on the sprocket 30 and the timing mark 38a on the sprocket 38 at the delayed position of the camshaft 34 as shown in FIGS. By comparison with their relative position in the advanced position of the camshaft 34 as shown.

  10 to 20 show two embodiments of the present invention in which a sprocket 132 shaped housing is supported on a camshaft 126 so as to swing. The camshaft 126, whether of an overhead camshaft type or a block camshaft type, may be considered a camshaft of a single camshaft engine. Alternatively, the camshaft 126 may be considered to be either the intake valve actuated camshaft or the exhaust valve actuated camshaft of both camshaft engines. In any case, both the sprocket 132 and the camshaft 126 are rotatable and are rotated by applying torque to the sprocket 132 by the endless roller chain 138 shown in part, the chain around and around the sprocket 132. It is hung around the crankshaft which is not done. As will be described in detail below, the sprocket 132 can swing over at least a limited arc with respect to the camshaft 126 during camshaft rotation, i.e., adjusting the phase of the camshaft 126 relative to the crankshaft. As described above, the camshaft 126 is swingably supported.

  An annular pumping vane 160 is fixedly disposed on camshaft 126, vane 160 has a diametrically opposed pair of radially outward lobes 160a and 160b, and bolt 162 expands camshaft 126. The bolt is attached to the end 126a, and the bolt penetrates the vane 160 to the end 126a. In this regard, the camshaft 126 is provided with a thrust shoulder 126b to ensure that the camshaft is accurately positioned with respect to the associated engine block not shown. The pumping vane 160 is accurately positioned with respect to the end 126a by a locating pin or mating pin 164 extending between the ends. The lobes 160a and 160b are respectively received in recesses 132a and 132b protruding radially outward of the sprocket 132, and the circumferential lengths of the recesses 132a and 132b are larger than the circumferential lengths of the vane lobes 160a and 160b. Larger, the vane lobe is received in the recess, allowing limited rocking motion of the sprocket 132 relative to the vane 160. The recesses 132a, 132b are respectively closed around the lobes 160a, 160b by spaced apart laterally extending annular plates 166, 168, which are fixed with respect to the vane 160, and thus one through the several lobes 160a and 160b. It is fixed with respect to the camshaft 126 by a bolt 170 extending from one to the other. Further, the inner periphery 132c of the sprocket 132 is sealed with respect to the outer periphery of the portion 160d of the vane 160, and the portion 160d is between the lobes 160a and 160b, and the tips of the lobes 160a and 160b of the vane 160 are sealed receiving slots 160e and 160e, respectively. 160f is provided, and a seal (not shown) is put therein. Therefore, each of the recesses 132a and 132b of the sprocket 132 can hold the hydraulic pressure, and the portions on each side of the lobes 160a and 160b can hold the hydraulic pressure in the recesses 132a and 132b, respectively. .

  The function of the structure shown in FIGS. 10 to 18 can be understood with reference to FIGS. However, the hydraulic pressure control device shown in FIG. 19 can be applied to the opposing hydraulic cylinder VCT device having the structure shown in FIGS. 1 to 9, similarly to the vane type VCT device having the structure shown in FIGS. .

  In any case, hydraulic fluid, typically in the form of engine lubricant, flows into the recesses 132a, 132b through a common inlet line 182. Inlet line 182 ends at the connection between opposing check valves 184 and 186, which are connected to recesses 132a and 132b by branch lines 188 and 190, respectively. Check valves 184 and 186 include annular seats 184a and 186a, respectively, to allow hydraulic fluid to flow into recesses 132a and 132b via check valves 184 and 186, respectively. Hydraulic fluid flow through check valves 184, 186 is blocked by floating balls 184a, 186b, respectively, which are elastically biased by seats 184a, 186a, respectively, by springs 184c, 186c, respectively. Accordingly, check valves 184, 186 allow initial filling of recesses 132a, 132b and provide a continuous supply of replenishment hydraulic fluid. The hydraulic fluid is best shown in FIG. 19 and its spool valve enters line 182 by a spool valve 192 incorporated in camshaft 126, and the hydraulic fluid enters recesses 132a, 132b by return lines 194, 196, respectively. To the spool valve 192.

  The spool valve 192 is made of a cylindrical member 198 and a spool 200 with a discharge hole, and the spool is slidable back and forth within the cavity 198a. The drainage spool or drainage spool 200 has cylindrical lands 200a and 200b at both ends thereof, and the lands 200a and 200b that fit snugly within the cylindrical member are shown schematically in FIGS. As shown, the land 200b prevents hydraulic fluid from flowing out of the return line 196, the land 200a prevents hydraulic fluid from flowing out of the return line 194, and the lands 200a and 200b are discharged from both return lines 194 and 196. Positioned to prevent hydraulic fluid outflow, where the camshaft 126 is held in an intermediate position selected with respect to the associated engine crankshaft, which position is referred to as the “null position” of the spool 200. Called.

  In the present invention, the position of the spool 200 with the discharge hole in the cylindrical member 198 is influenced by the spring 202 acting on the end of the land 200a. Accordingly, the spring 202 elastically biases the spool 200 to the left as shown in FIGS. The intake line 182 receives pressurized fluid (engine oil) directly from the main oil tank (MOG) 230 of the engine by a conduit 230a that bypasses the spool 200 with the discharge hole. This oil is used to lubricate the bearing 232, in which the engine camshaft 126 rotates.

  Control of the position of the spool 200 within the member 198 is directly responsive to an electromechanical actuator 201, preferably a variable force solenoid, as shown in FIG. Current is directed through the cable 238 through the solenoid housing 201d into the solenoid coil 201a, which bounces or pushes the armature 201b. The armature 201b abuts on the extension 200c of the spool 200 with the discharge hole, and thereby moves the spool 200 with the discharge hole to the right as shown in FIG. If the force of the spring 202 is balanced with the force applied in the opposite direction by the armature 201b, the spool 200 will remain in the zero or center position. Thus, the drained spool 200 can be moved in either direction by increasing or decreasing the current to the solenoid coil 201a as needed. Of course, the shape of the solenoid 201 is reversed, and the force acting on the spool extension 200c is converted from “push” to “pull”. This requires that the function of the spring 202 react to the force in the new direction of movement of the redesigned armature 201b. However, it may be desirable for the spool to be pushed to a far left or biased position. When the spring 202 in the cavity 198c as shown in FIG. 19 or in the cavity 198a as shown in FIG. 20 has no current flowing through the solenoid coil 201a, such as during lack of power or engine shutdown. It is ensured that the spool 200 returns to the biased position.

  The movement of the armature 201b is controlled by a current applied to the solenoid coil 201a in response to a control signal from an electronic engine control unit (ECU) 208 schematically shown in FIG. 19, and the control unit has a normal structure. . The control unit receives the crankshaft and camshaft position signals detected by the sensors 207a and 207b. In a previous variation of the VCT device, the force applied to the spool extension 200c is within the cavity 198a acting on the spring 202 force and the end of the land 200a if the center or zero position of the spool 200 is desired. It must be balanced with the sum of the system hydraulics. Problems have arisen when attempting to achieve this balance because the device included components that can be significantly changed, i.e., hydraulics. The optimal solution is a control device independent of variable parameters, ie a device independent of engine oil pressure.

  In the present invention, the hydraulic pressure in the cavity 198a is released and only the force of the armature 201b is balanced against the force of the spring 202 to achieve the zero position of the spool 200. Relieving the pressure in the cavity 198a is achieved, for example, by providing an engine oil passage that bypasses the spool in the vane device. That is, oil is supplied to the inlet line 182 as in the previous device without using a passage into the spool 200. Bypassing the spool 200 can be accomplished by connecting the bypass line 220a directly to the inlet line 182 and replacing the inlet oil check valve 222a with a check valve previously included in the internal passage of the spool. . In combination with providing an alternative flow path, releasing the spool valve 198 into the atmosphere through the vent 198d achieves the purpose of releasing the pressure in the cavity 198a, and the pressure in the cavity is It acts on the end of the land 200A in the VCT apparatus.

  When the variable oil pressure is removed, the force considered for controlling the position of the spool 200 with the discharge hole is a pressure whose rate of change cannot be determined. The force of the armature 201b corresponds to the current passed through the solenoid coil 201a, and the force of the spring 202 can be asserted (with respect to the spring position). The effect is that the position of the spool 200 can be easily ascertained based solely on the solenoid current.

  The type of solenoid commonly used in the preferred embodiment is a cylindrical armature or a variable area solenoid as shown in FIG. The main air gap 201c extends radially around the armature and may include a non-magnetic bearing material. When the armature 201b moves in the axial direction, the cylindrical area of the main gap 201c increases, but the force and the distance to the coil are kept constant. Since the force is relatively insensitive to the position of the axial armature, an extremely precise distance from the solenoid housing 201d to the spool 200 with the discharge hole is not necessary.

  An alternative embodiment of the present invention is shown in FIG. A flat surface armature or a variable gap force variable solenoid is used. The force is inversely proportional to the square of the air gap 201c. It is beneficial to limit the air gap 201c to a relatively small value. By using a stroke amplifier in combination with a variable gap solenoid, a net gain in force is achieved. The lever device 201e connects the armature 201b with the spool extension 200c and provides such a gain in force. The net gain is facilitated by reducing the physical size of the electromechanical armature 201, thus reducing the current requirements of the solenoid coil 201a without sacrificing valve movement.

  To move the spool in one direction or the other, by using only the unbalance between the force generated electrically at one end 200a of the spool 200 and the spring force acting on the other end 200b (common at both ends) 19 and 20 is completely independent of the hydraulic system pressure (as opposed to using an imbalance between hydraulic loads from the hydraulic source). Thus, it is not necessary to design a compromised device, such as a device believed to be due to the individual characteristics of a particular engine, to operate over a potentially wide range of hydraulic pressures. In that regard, by designing a device that operates within a narrow range of parameters, it is possible to quickly and accurately position the spool 200 at its zero position for enhanced operation of the VCT device.

  The vane 160 is alternately biased clockwise and counterclockwise by the torque pulsation of the camshaft 126, and these torque pulsations attempt to cause the vane 160 and thus the camshaft 126 to swing relative to the sprocket 132. However, in the spool position shown in FIGS. 19 and 20, such swinging is prevented by hydraulic fluid in the recesses 132a, 132b of the sprocket 132 on either side of the lobes 160a, 160b of the vane 160. This is because the hydraulic fluid is not discharged from either of the recesses 132a and 132b. Both return lines 194 and 196 are blocked by the position of the spool 200 with the discharge hole. For example, if it is desired to allow camshaft 126 and vane 160 to move counterclockwise with respect to sprocket 132, it is only necessary to increase the amount of current to solenoid coil 201a. This "pushes" the armature 201b to the right, biases the spool to the right, thereby releasing the return line 194. In this state of the device, the counterclockwise torque pulsation in the camshaft 126 pumps fluid out of the recess 132a, and the lobe 160b of the vane 160 is the other part of the recess 132a where the hydraulic fluid is emptied. Allow to move in. However, the reverse movement of the vane 160 does not occur because the torque pulsation of the camshaft 126 is reversed. This is because the land 200b of the spool 200 prevents fluid flow through the return line 196. Although shown as a separate closed passage in FIGS. 19 and 20, the periphery of the vane 160 is a slot defining an open oil passage as shown in FIGS. 10, 11, 15, 16, and 17. 160c, which slot allows oil transfer between the right recess 132a portion of the lobe 160a and the right recess 132b portion of the lobe 160b (the portions are the non-operating side of the lobes 160a and 160b). Therefore, when the flow is allowed through the return line 194, the vane 160 moves counterclockwise with respect to the sprocket 132, and when allowed through the flow return line 196, the clockwise direction. Movement occurs.

  Further, the inlet line 182 is provided with an extension 182a on one non-operating side of the lobe 160a or 160b, shown as a lobe 160b, to provide good rotational balance, improved damping of the vane and vane 160. Because of the improved lubrication of the support surface, the compensation oil is allowed to be continuously supplied to the non-operating side of the lobes 160a, 160b. The flow of compensation oil has no effect and is not affected by the operation of the electromechanical actuator 201. Compensation oil continues to be supplied to lobes 160a and 160b.

  While the best mode contemplated by the inventor for practicing the invention at the time of filing has been set forth herein, appropriate modifications, variations, and the like may be made without departing from the scope of the invention. It will be apparent to those skilled in the art that this can be done.

effect

  According to the present invention, the phase error between the crankshaft and the camshaft can be effectively corrected.

1 is a partial view of a two camshaft internal combustion engine incorporating an embodiment of a variable camshaft timing device according to the present invention, with a cut along a plane extending laterally through the camshaft and crankshaft, and a crankshaft and exhaust camshaft. It is a figure which shows the intake camshaft in the position delayed later. FIG. 2 is a partial view similar to that of FIG. 1 and showing the intake camshaft in an advanced position with respect to the exhaust camshaft. FIG. 7 is a fragmentary view taken along line 3-3 of FIG. 6 with portions of the structure removed and shown in a delayed position of the device for the sake of brevity. FIG. 4 is a partial view similar to FIG. 3 showing the intake camshaft in an advanced position with respect to the exhaust camshaft. FIG. 2 is a partial view showing several inversion sides of the structure shown in FIG. 1. FIG. 6 is a partial view taken along line 6-6 of FIG. FIG. 7 is a partial view taken along line 7-7 in FIG. 1. It is sectional drawing cut | disconnected along line 8-8 of FIG. FIG. 9 is a cross-sectional view taken along line 9-9 in FIG. It is an elevational view of a camshaft having another embodiment of a variable camshaft timing device. FIG. 11 is a view similar to FIG. 10 with portions of the structure removed to more clearly explain the other parts. It is sectional drawing cut | disconnected along line 12-12 of FIG. It is sectional drawing cut | disconnected along line 13-13 of FIG. It is sectional drawing cut | disconnected along line 14-14 of FIG. FIG. 15 is an end elevation view of elements of the variable camshaft timing device of FIGS. 10-14. FIG. 16 is an elevational view of the element of FIG. 15 viewed from the opposite end. FIG. 17 is a side elevation view of the elements of FIGS. 15 and 16. FIG. 18 is an elevational view of the element of FIG. 17 viewed from the opposite side. FIG. 19 is a simplified schematic diagram of the variable camshaft timing device of FIGS. 10 to 18. FIG. 20 is a simplified schematic diagram similar to FIG. 19 of an alternative embodiment of the present invention.

Explanation of symbols

126 Camshaft 132 Housing 132a, 132b Recess 160 Vane 160a, 160b Lobe 184, 186 Check valve 188 Conduit means or line 190 Conduit means or line 192 Spool valve 194 Conduit means or line 196 Conduit means or line 198 Spool valve body 200 Spool 200a, 200b Land 201 Electromechanical actuator 202 Spring 207 Detection means or sensor 208 Control unit

Claims (1)

In an internal combustion engine having a variable camshaft timing device that changes the phase angle of the camshaft relative to the crankshaft, rotational motion is rotated from the crankshaft together with the camshaft to change the phase angle of the camshaft relative to the crankshaft. In a method for controlling the flow of hydraulic fluid from a fluid source to a means for transmitting to the camshaft via a housing that is capable of swinging with respect to the crankshaft and attached to the camshaft ,
Detecting the positions of the camshaft and crankshaft;
Calculating a relative phase angle between the camshaft and the crankshaft, the calculating using an engine control unit for processing the information obtained from the detection and controlling the engine The unit emits an electrical signal corresponding to the phase angle;
Controlling the position of a spool slidably disposed within the spool valve body and relieving pressure in the cavity of the spool valve, wherein the controlling is responsive to the signal received from the engine control unit Using the electromechanical actuator having a force variable solenoid to change the position of the spool having the exhaust hole;
Supplying hydraulic fluid from the fluid source through the spool valve to the means for transmitting rotational motion from the crankshaft to the camshaft, the spool valve passing through an inlet line and a return line. Allowing and preventing hydraulic fluid flow into the housing;
Controlling the position of the spool to transmit rotational motion to the camshaft and selectively permit or block hydraulic fluid flow to change the camshaft phase angle relative to the crankshaft;
A method for controlling the flow of hydraulic fluid.

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