JP2014194161A - Valve timing control device of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce discomfort felt by an operator by suppressing fluctuation of engine output without largely changing a valve timing even during execution of a cleaning mode.SOLUTION: An ECU 51 checks whether a cam follower exists on a base circle of an intake cam 19a or not (S12) on the basis of the cam follower connected to an intake valve, and a cam position of the intake cam 19a slidably kept into contact with the cam follower, when a cleaning mode executing condition is satisfied, and makes a spool 36g of a hydraulic control valve 36 execute a cleaning motion (S13) when it exists on the base circle.

Description

  The present invention relates to a valve timing control device for an engine that performs a cleaning operation of a hydraulic control unit that controls a hydraulic pressure supplied to a variable valve timing mechanism when a cleaning mode execution condition is satisfied.

  In recent years, an engine having a variable valve timing mechanism that adjusts the rotational phase between the crankshaft and the camshaft of the engine has been put into practical use. The variable valve timing mechanism is controlled to continuously change the valve timing of at least one of the intake valve and the exhaust valve.

  Here, the variable valve timing mechanism generally employs a hydraulic drive type driven by hydraulic pressure, but the oil supplied to the variable valve timing mechanism has impurities due to deterioration over time of use or during cutting. Foreign matter such as fine chips floats, and impurities and foreign matter in the oil are likely to settle and accumulate when the amount of circulating oil in the hydraulic system is small, especially hydraulic control valves that operate the variable valve timing mechanism, etc. This causes deterioration of slidability in the sliding portion of the hydraulic circuit and malfunction due to biting of foreign matter.

  For this reason, conventionally, there has been provided a cleaning mode in which the hydraulic control valve is reciprocated under a predetermined condition to change the hydraulic pressure to clean the sliding portion and the oil passage of the hydraulic circuit. Japanese Patent No. -263102) discloses a technique for performing the cleaning mode when the engine water temperature and the engine speed are equal to or higher than a predetermined value in order to minimize fluctuations in the engine torque when the cleaning mode is performed.

JP 2001-263102 A

  However, the technique disclosed in the above-described document merely limits the region where the cleaning mode is performed, and the valve timing is varied when the cleaning mode is performed even in such a region. For this reason, the engine output changes, causing problems such as a decrease in the engine speed, which gives the driver an uncomfortable feeling.

  In view of the above circumstances, the present invention provides a valve for an engine in which the valve timing does not fluctuate greatly even during the execution of the cleaning mode, the fluctuation in engine output is suppressed, and the uncomfortable feeling given to the driver can be reduced. An object is to provide a timing control device.

  The valve timing control device for an engine according to the present invention includes a variable valve timing mechanism that adjusts a rotational phase between an engine drive shaft and a cam shaft by hydraulic pressure, and a cam follower that is in sliding contact with a cam body provided on the cam shaft. A valve body that opens and closes, a hydraulic pressure control means that controls the hydraulic pressure of the variable valve timing mechanism, and operates the hydraulic pressure control means to control the variable valve timing mechanism in accordance with the engine operating state and implement a cleaning mode. A control unit that determines a condition and causes the hydraulic pressure control unit to perform a clean operation when the cleaning mode execution condition is satisfied, and when the cleaning mode execution condition is satisfied, the control unit moves the cam follower on the cam body. However, the valve timing of the variable valve timing mechanism should not be changed. Checked whether the position, when in the position which does not vary the valve timing, it perform the cleaning operation.

  According to the present invention, the cleaning operation of the hydraulic control means for controlling the hydraulic pressure of the variable valve timing mechanism is performed so that the cam follower connected to the valve body is on the cam body and the valve timing of the hydraulically driven variable valve timing mechanism is not changed. Since the cleaning operation is performed when the vehicle is in the position, the valve timing does not fluctuate greatly even during the cleaning mode, the engine output fluctuation is suppressed, and the driver feels uncomfortable. be able to.

1 is a schematic configuration diagram of a variable valve timing mechanism according to a first embodiment. FIG. 2 is an explanatory view showing the most advanced angle state of the variable valve timing mechanism in the AA cross section of FIG. FIG. 2 is an explanatory diagram showing the most retarded state of the variable valve timing mechanism in the AA cross section of FIG. Same schematic diagram of valve timing control device The flowchart showing the valve timing control routine The flowchart showing the cleaning mode execution subroutine Same as above, time chart showing cam lift changes Time chart showing cleaning mode execution area according to the second embodiment Same as above, time chart showing changes in cam torque generated on camshaft (A) is a schematic diagram of the most advanced angle state of the variable valve timing mechanism, (b) is a schematic diagram of the most retarded angle state of the variable valve timing mechanism.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[First Embodiment]
1 to 7 show a first embodiment of the present invention. Reference numeral 21 in FIG. 1 denotes a variable valve timing mechanism. In this embodiment, a state provided in the intake camshaft 19 of a horizontal or V-type DOHC four-cylinder engine is exemplified. Intake cams 19a and 19a 'as cam bodies for individually opening and closing the intake valves of the two cylinders are fixed. In addition, each intake cam 19a, 19a 'is slidably contacted with a cam follower which is connected to an intake valve as a valve body and opens and closes the intake valve.

  In the following, for convenience, the intake cam 19a on the variable valve timing mechanism 21 side will be referred to as the # 1 cylinder intake cam 19a, and the rear intake cam 19a 'will be referred to as the # 2 cylinder intake cam 19a'. The variable valve timing mechanism 21 may be provided on the exhaust cam shaft side, or may be provided on both the intake cam shaft 19 and the exhaust cam shaft.

  The variable valve timing mechanism 21 is disposed between the intake camshaft 19 and the intake cam pulley 23, and relatively rotates the intake cam pulley 23 and the intake camshaft 19, thereby driving the engine drive shaft (generally, Since it is a “crankshaft”, it is a hydraulically driven mechanism that continuously changes the rotational phase (displacement angle) of the intake camshaft 19 relative to the “crankshaft”. The hydraulic pressure of the variable valve timing mechanism 21 is switched by a hydraulic control valve (OCV) 36 as a hydraulic control means including a linear solenoid valve or a duty solenoid valve, and an electronic control unit (ECU) 51 described later. It operates according to the drive signal from (see FIG. 4).

  The intake camshaft 19 is rotatably supported between the cylinder head 2 and a bearing cap (not shown), and has three vanes 28a at the tip of the intake camshaft 19 as shown in FIGS. A vane rotor 28 is attached by bolts 29 so as to be integrally rotatable.

  A housing 30 and a housing cover 31 are attached to the intake cam pulley 23 by bolts 32 so as to be integrally rotatable. In addition, a large number of external teeth 23 a for hooking a timing belt (not shown) are formed on the outer periphery of the intake cam pulley 23.

  Then, the intake cam shaft 19 passes through the housing cover 31 so as to be rotatable, and each vane 28a of the vane rotor 28 fixed to the intake cam shaft 19 is formed in three fan-shaped spaces formed in the housing 30 integral with the intake cam pulley 23. The part 33 is stored in a freely rotatable manner. Each fan-shaped space 33 is partitioned into an advance chamber 33a and a retard chamber 33b by vanes 28a.

  The advance chamber 33a communicates with the A port 36a of the hydraulic control valve 36 through the advance side oil passages 28b, 19b, 34 formed in the vane rotor 28, the intake camshaft 19, and the cylinder head 2, respectively. The corner chamber 33b is communicated with the B port 36b of the hydraulic control valve 36 through the retard angle side oil passages 28c, 19c, 35 formed in the vane rotor 28, the intake camshaft 19, and the cylinder head 2, respectively.

  The hydraulic control valve 36 is connected to an oil supply port 36 c connected to an oil supply passage 40 to which oil, that is, a predetermined hydraulic pressure is supplied from an oil pan 37 through an oil pump 38 and an oil filter 39, and to two drain passages 41 and 42. A spool 36g having drain ports 36d and 36f communicating with each other and having four lands and three passages formed between the lands are reciprocated in the axial direction, whereby an A port 36a and a B port 36b, The oil supply port 36c and the drain port 36d or 36f are selectively communicated.

  In the present embodiment, the hydraulic control valve 36 is a four-way control valve whose energization current is controlled by a duty signal from the ECU 51 described later, and the spool 36g moves in the axial direction in proportion to the energization current, The flow direction is switched and the opening of the passage is adjusted to adjust the magnitude of the hydraulic pressure supplied to each advance chamber 33a and retard chamber 33b.

  Reference numeral 28d denotes a stopper pin inserted into the vane 28a of the vane rotor 28. As shown in FIG. 3, when the variable valve timing mechanism 21 is in the most retarded state, the hole 28a formed in the housing 30 is inserted into the hole 30a. Engage and position. The most retarded angle position of the variable valve timing mechanism 21 due to this mechanical engagement is calibrated by the ECU 51 described later based on the rotational phase (displacement angle) of the intake camshaft 19 with respect to the crankshaft calculated based on the signal from the sensor. Therefore, the deviation from the actual displacement angle (actual valve timing) of the intake camshaft 19 calculated from the sensor value at this reference position is learned. 2 shows the most advanced angle state of the variable valve timing mechanism 21, and FIG. 3 shows the most retarded state of the variable valve timing mechanism 21.

  The variable valve timing mechanism 21 described above has a crank angle sensor 44 for outputting a crank pulse representing a crank angle of a crankshaft (not shown) as a sensor for detecting its operating position, and a rear end of the intake camshaft 19. A cam position that detects a plurality of protrusions (detected portions) provided at equal angles on the outer periphery of the cam rotor 45 that is fixedly rotated synchronously, and outputs a cam position pulse that represents the cam positions of the intake cams 19a and 19a ′. Sensor 46 is used.

  The crank pulse output from the crank angle sensor 44 and the cam position pulse output from the cam position sensor 46 are input to the ECU 51 as control means. The ECU 51 is mainly composed of a computer, and calculates the actual displacement angle (actual valve timing) of the intake cam position with respect to the reference crank angle based on the crank pulse and the cam position pulse. The variable valve timing mechanism 21 is feedback-controlled so that it converges to the target valve timing set based on it.

  In the present embodiment, as the duty ratio of the control signal output from the ECU 51 increases, the hydraulic control valve 36 has a larger energization current value, and the spool 36g moves to the left as shown in FIG. As the displacement angle of the intake camshaft 19 relative to the angle is advanced and the duty ratio of the control signal is smaller, the energization current value becomes smaller and the spool 36g moves to the right as shown in FIG. The displacement angle of the shaft 19 is retarded.

  Output signals of the crank angle sensor 44 and the cam position sensor 46 are processed in the ECU 51 shown in FIG. The ECU 51 has a function of controlling the variable valve timing in addition to the function of controlling the engine operating state, such as fuel injection control and ignition timing control. As a function of controlling the variable valve timing, a control amount for the hydraulic control valve 36 for adjusting the hydraulic pressure supplied to the variable valve timing mechanism 21 is calculated, and the rotational phase of the intake camshaft 19 is adjusted, whereby the intake valve Control valve timing for.

  In the valve timing control by the variable valve timing mechanism 21, the rotational phase of the intake cam position relative to the reference crank angle based on the crank pulse output from the crank angle sensor 44 and the cam position pulse output from the cam position sensor 46. That is, the actual displacement angle (actual valve timing) of the intake camshaft 19 with respect to the crankshaft is calculated, and the control current value of the hydraulic control valve 36 is adjusted so that the actual valve timing converges to the target valve timing set based on the engine operating state. And a duty signal giving this control current value is output to the hydraulic control valve 36 to feedback control the variable valve timing mechanism 21.

  At that time, the ECU 51 executes a cleaning mode in which the spool 36g of the hydraulic control valve 36 is forcibly advanced and retracted in order to prevent malfunction of the hydraulic control valve 36 due to accumulation of impurities in the oil and foreign matter accumulation / precipitation. Judgment is made on whether or not.

  The execution condition of the cleaning mode is, for example, checking the actual control duty dVVT of the hydraulic control valve 36 in which the variable valve timing mechanism 21 is operating, and the control duty dVVT of the hydraulic control valve 36 is normal operation of the variable valve timing mechanism 21. Check whether it is within the guaranteed setting range. When the state where the control duty dVVT is outside the setting range continues for a set time or more, it is determined that the cleaning mode execution condition is satisfied.

  Hereinafter, processing related to valve timing control by the ECU 51 will be described in accordance with a valve timing control routine shown in FIG.

  This routine is executed every predetermined time after the ECU 51 is turned on and the system is initialized after the ignition switch is turned on. First, in step S1, parameters for determining the cleaning mode execution condition are read. Compare with the execution condition judgment value. In the present embodiment, the control duty dVVT for the current hydraulic control valve 36 is used as a parameter for determining the cleaning mode execution condition. Then, it is checked whether or not the control duty dVVT is out of the set range, and if it is out of the set range, whether or not the duration exceeds the set time.

  Then, the process proceeds to step S2, and if the control duty dVVT is out of the set range and the duration exceeds the set time, it is determined that the cleaning mode execution condition is satisfied, and the process proceeds to step S3. On the other hand, if the control duty dVVT is within the set range or the control duty dVVT is outside the set range, if the duration does not exceed the set time, it is determined that the cleaning mode execution condition is not satisfied. Then, the process proceeds to step S4, the valve timing normal control is executed, and the routine is exited. Note that the normal valve timing control is a technique already known in Japanese Patent Application Laid-Open No. 2003-222034 previously filed by the present applicant, and therefore description thereof is omitted here.

  In step S3, the cleaning mode is executed and the routine is exited. This cleaning mode is processed according to the cleaning mode execution subroutine shown in FIG.

  In this subroutine, first, in step S11, the cam positions of the intake cams 19a and 19a 'are detected based on the cam position pulse output from the cam position sensor 46. In step S12, the cam followers that are in sliding contact with the intake cams 19a and 19a ′ and that open and close the intake valves of the # 1 cylinder and the # 2 cylinder by the cam lift of the intake cams 19a and 19a ′ are both intake cams 19a. , 19a ′, that is, whether or not the valve timing of the variable valve timing mechanism 21 does not vary greatly even under the influence of the generated cam torque. Exit. On the other hand, when both cam followers are on the base circle, that is, when it is determined that both cam followers are in the overlapping region of FIG. 7, the process proceeds to step S13, and the control duty dVVT of the current supplied to the hydraulic control valve 36 is set. The maximum current is set to 100 [%] and the minimum current is set to 0 [%] alternately every predetermined time, and the process returns to step S12.

  When the control duty dVVT of the current flowing through the hydraulic control valve 36 is set to 100 [%], as shown in FIG. 2, the spool 36g protrudes to the left, and when the control duty dVVT is set to 0 [%] As shown in FIG. 3, the spool 36g moves backward in the right direction. In this embodiment, the reciprocating operation from the maximum position to the minimum position of the spool 36g is referred to as a cleaning operation.

  Then, the sliding operation and the oil passage of the hydraulic control valve 36 are cleaned by the cleaning operation of the spool 36g, and the sliding failure due to the biting of foreign matter and accumulation of impurities is recovered. The hydraulic pressure supplied to the variable valve timing mechanism 21 is fluctuated by the advance / retreat operation of the spool 36g, and the vane rotor 28 is advanced or retarded. However, the area where the cleaning is performed controls the intake valve of each cylinder. Since the cam followers to be opened and closed are both located on the base circles of the intake cams 19a and 19a ′ (the overlapping region in FIG. 7), the cam torque generated in the intake cam shaft 19 is small. Therefore, the valve timing of each cylinder does not fluctuate greatly, fluctuations in engine output such as a decrease in engine speed are suppressed, and a sense of incongruity given to the driver can be reduced.

[Second Embodiment]
8 to 10 show a second embodiment of the present invention. In the first embodiment described above, the cleaning is performed when the cam follower that opens and closes the intake valve of each cylinder is on the overlapping region of the base circles of the intake cams 19a and 19a ′. Then, the operation is performed when the vane rotor 28 of the variable valve timing mechanism 21 is in the most advanced position or the most retarded position. In addition, about the component common in 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 9, when the cam crests of the intake cam 19a of the # 1 cylinder and the intake cam 19a 'of the # 2 cylinder try to open and close the intake valve via the cam follower, the first half, that is, the cam crest Until the peak is reached, a positive cam torque is generated in each of the intake cams 19a, 19a 'to return to the retard direction. On the other hand, in the second half after the cam followers have passed the tops of the cam peaks of the intake cams 19a and 19a ', negative cam torque is generated to advance the intake cams 19a and 19a' in the advance direction.

  Therefore, as shown in FIG. 10A, when the negative cam torque is generated with respect to the intake cams 19a and 19a 'when the rotational phase of the vane rotor 28 is at the most advanced angle state, The advance side surface of the vane 28a formed on the vane rotor 28 comes into contact with the partition wall of the housing 30, and the rotation in the advance direction is restricted. On the other hand, when a positive cam torque is generated with respect to the intake cams 19a and 19a 'when the rotational phase of the vane rotor 28 is in the most retarded state, as shown in FIG. The retard angle side end surface of the vane 28a formed on the vane rotor 28 contacts the partition wall of the housing 30, and the rotation in the retard angle direction is restricted.

  Accordingly, when the advance side surface of the vane 28a formed on the vane rotor 28 is in contact with the partition wall of the housing 30 and when the negative cam torque is generated, or the retard side end surface of the vane 28a is When the positive cam torque is generated while being in contact with the partition wall of the housing 30, the valve timing of the variable valve timing mechanism 21 is affected by the generated cam torque even if cleaning is performed. It does not fluctuate greatly.

  The cleaning mode execution subroutine shown in FIG. 8 is applied instead of the subroutine shown in FIG. 6 of the first embodiment described above. First, based on the cam position pulse output from the cam position sensor 46 in step S21, the intake air intake subroutine is applied. The cam positions of the cams 19a and 19a ′ are detected.

  Then, the process proceeds to step S22, where it is determined whether or not the rotational phase of the vane rotor 28 is in the most advanced angle state based on the cam position detected by the cam position sensor 46. If not, the process branches to step S23. In the most advanced angle state, the process proceeds to step S24.

  In step S24, whether or not negative cam torque is generated in the intake cams 19a and 19a ′ based on the cam position and preset cam follower position data, that is, the cam followers are cam crests of the intake cams 19a and 19a ′. It is determined whether or not it is in the second half. If the cam follower is in the second half of the cam crest of the intake cams 19a and 19a ', it is determined that negative cam torque is generated, and the process proceeds to step S26 to perform cleaning. On the other hand, if the cam follower is not in the second half of the cam crest of the intake cams 19a and 19a ', the routine is directly exited.

  Further, when the process proceeds from step S22 to step S23, it is checked whether or not the rotational phase of the vane rotor 28 is in the most retarded state based on the cam position detected by the cam position sensor 46. If it is missing or in the most retarded state, the process proceeds to step S25. In step S25, based on the cam position and preset position data of the cam follower, whether or not positive cam torque is generated in the intake cams 19a and 19a ', that is, the cam follower is a cam crest of the intake cams 19a and 19a'. It is determined whether or not it is in the first half. If the cam follower is in the first half of the cam crest of the intake cams 19a and 19a ', it is determined that the positive cam torque is generated, and the process proceeds to step S26 to perform cleaning.

  Then, when the process proceeds from step S24 or step S25 to step S26, the control duty dVVT of the current supplied to the hydraulic control valve 36 is set to 100 [%] of the maximum current and 0 [%] of the minimum current to perform cleaning. Then, the routine is switched over alternately at predetermined intervals. The cleaning operation for moving the spool 36g forward / backward by switching the control duty dVVT is the same as that in the first embodiment described above, and a description thereof will be omitted.

  Thus, in the present embodiment, when the rotational phase of the vane rotor 28 is in the most advanced angle state, cleaning is performed only when the negative cam torque is generated in the intake cams 19a and 19a ′. When the rotational phase is in the most retarded state, the cleaning is performed only when the positive cam torque is generated in the intake cams 19a and 19a '. Therefore, when cleaning, the spool 36g of the hydraulic control valve 36 is increased. Since the vane rotor 28 is pressed against the partition wall of the housing 30 even when the advancing / retreating operation is performed, the valve timing of each cylinder does not fluctuate greatly, and fluctuations in the engine output, such as a decrease in engine speed, are suppressed and operation is performed. The discomfort given to the person can be reduced.

  The present invention is not limited to the above-described embodiments. For example, both the cleaning execution area in the first embodiment and the cleaning execution area in the second embodiment may be combined for cleaning. .

19 ... intake camshaft,
19a, 19a '... intake cam,
21 ... Variable valve timing mechanism,
28 ... Vane rotor,
28a ... Vane,
36 ... Hydraulic control valve,
36g ... Spool,
44 ... Crank angle sensor,
45 ... Cam rotor,
46: Cam position sensor,
51 ... Electronic control unit,
dVVT: Control duty

Claims (4)

A variable valve timing mechanism that hydraulically adjusts the rotational phase between the engine drive shaft and the camshaft;
A valve body that opens and closes via a cam follower that is in sliding contact with a cam body provided on the camshaft;
Hydraulic control means for controlling the hydraulic pressure of the variable valve timing mechanism;
Control for operating the hydraulic control means to control the variable valve timing mechanism in accordance with an engine operating state, determining a cleaning mode execution condition, and causing the hydraulic control means to perform a clean operation when the cleaning mode execution condition is satisfied. Means and
When the cleaning mode execution condition is satisfied, the control means checks whether the cam follower is on the cam body and is in a position where the valve timing of the variable valve timing mechanism is not changed, and changes the valve timing. The valve timing control device for an engine, wherein the cleaning operation is performed when the position is not to be performed. 2. The valve timing control device for an engine according to claim 1, wherein the position where the valve timing of the variable valve timing mechanism is not varied is when the cam follower is on a base circle of the cam body. The position where the valve timing of the variable valve timing mechanism is not varied is a position where the variable valve timing mechanism is at the most advanced angle position and the cam follower generates a negative cam torque with respect to the cam body. The valve timing control device for an engine according to claim 1 or 2. The position where the valve timing of the variable valve timing mechanism is not varied is a position where the variable valve timing mechanism is at the most retarded position and the cam follower generates a positive cam torque with respect to the cam body. The valve timing control device for an engine according to any one of claims 1 to 3.

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