JP4236362B2 - Valve timing adjusting device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a valve timing adjusting device for an internal combustion engine, and in particular, when the supply hydraulic pressure of a rotation transmission member that changes the rotation phase between a camshaft driving a valve and a crankshaft of the internal combustion engine is reduced by hydraulic pressure, The present invention relates to a valve timing adjusting device for an internal combustion engine, in which fluctuations in the operation timing of intake valves and exhaust valves are reduced and the controllability is improved by controlling hydraulic pressure so that the amount of oil supply and oil discharge to a hydraulic chamber is reduced.
[0002]
[Prior art and problems to be solved by the invention]
It is desirable that the start timing and end timing of intake or exhaust of the internal combustion engine (engine) be set appropriately in accordance with the operating state of the engine. Therefore, conventionally, as a device for appropriately setting the start timing and end timing of intake or exhaust of an engine, a camshaft is used by using a rotation transmission member in which a retard chamber and an advance chamber are formed. There is known a valve timing adjusting device that changes the position in the rotation direction of the valve. In this valve timing adjusting device, the camshaft for driving the valve is controlled by controlling the hydraulic pressure in the retard chamber and advance chamber of the rotation transmitting member so that an appropriate valve timing can be obtained according to the operating state of the engine. The rotational phase with the engine crankshaft has been changed. The hydraulic pressure in the advance chamber and retard chamber is adjusted by controlling the duty ratio of the electromagnetic solenoid by an electronic control device and controlling the position of the spool of the hydraulic control valve connected to the oil pump and the oil pan.
[0003]
In this hydraulically driven valve timing adjusting device, the phase fluctuation range of the actual valve timing increases due to camshaft driving torque fluctuations due to the drop in hydraulic pressure supplied from the oil pump, the air mixed in the oil, oil leakage, etc. . As shown in FIG. 1, this phase fluctuation width is substantially inversely proportional to the supply pressure (supply hydraulic pressure) of the oil pump, and increases as the supply pressure of the oil pump decreases.
[0004]
As a conventional technique for reducing the phase fluctuation width of the actual valve timing due to cam shaft driving torque fluctuation, a technique described in Japanese Patent Laid-Open No. 9-144571 is known. In this technique, the correction duty ratio is calculated for each cam angle from the correction data corresponding to the torque change, the intake pressure, and the engine rotation speed, and the drive duty ratio of the hydraulic control valve is corrected.
[0005]
However, the conventional technology is a technology that prevents deterioration of controllability due to camshaft drive torque fluctuations under certain conditions where sufficient supply oil pressure can be obtained, and reduces the camshaft phase fluctuation width when supply oil pressure drops. It is not a technology to do. This is also clear from the fact that the supply hydraulic pressure is not taken into account in the correction data calculation formula in the above-described conventional technology. The supply hydraulic pressure decreases as the engine temperature increases and the engine rotation speed decreases. If the duty ratio for controlling the opening of the hydraulic control valve is constant, the camshaft drive torque cannot be balanced. That is, the cam shaft phase fluctuation caused by torque fluctuation is affected by the supply hydraulic pressure, and cannot be suppressed by the corrected duty ratio calculated without considering the hydraulic pressure.
[0006]
Therefore, in order to prevent deterioration of controllability in response to changes in hydraulic pressure in the above-described prior art, it is necessary to add a variable related to the supply hydraulic pressure to the correction duty ratio calculation formula, but adding this variable makes the calculation complicated. There is a problem of becoming.
[0007]
Further, the duty ratio correction control proportional to the torque change in the related art is compared with the case where the hydraulic control valve is controlled to a substantially fully closed position (near the holding duty ratio) where the oil supply amount and the oil discharge amount are reduced. Since the amount of oil flowing out from the chamber increases, the effect of reducing the camshaft fluctuation width is small.
[0008]
Further, in the above publication, in the helical gear type valve timing adjusting device, the valve timing is changed only when the direction in which the cam shaft is moved coincides with the direction of the cam shaft driving torque, and the torque direction is reversed. In this case, by controlling the hydraulic control valve to the holding duty ratio (fully closed), the force acting on the ring gear (the position in the rotational direction of the camshaft changes due to the movement in the axial direction) is limited to a certain direction, It describes that the camshaft moves smoothly to the target advance amount.
[0009]
When this control method is applied when the supply oil pressure is lowered, the cam shaft phase fluctuation width is as shown in Conventional Example B of FIGS. 4 (a) and 4 (b). In the figure, the camshaft driving torque has a positive torque range when torque in the direction opposite to the rotation is generated. In this conventional example B, when the direction in which the cam shaft is moved coincides with the direction of the driving torque, the valve timing is changed. Therefore, when the hydraulic control valve is controlled to the driving duty ratio, the torque is balanced. Since the hydraulic chamber to be raised communicates with the oil discharge passage, the oil flows out and the pressure rise is moderated. In addition, when the direction of the camshaft movement and the direction of torque are opposite, the oil pressure control valve is controlled to the holding duty ratio (fully closed), so an oil pump is installed in the hydraulic chamber where the pressure should be increased to balance the torque. It becomes impossible to supply the hydraulic pressure from. Therefore, as shown in FIG. 4, the phase fluctuation width of the camshaft increases compared to the conventional example A in which the hydraulic control valve is controlled with a constant duty ratio regardless of the camshaft driving torque.
[0010]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a valve timing adjusting device that prevents an increase in the phase fluctuation width of the camshaft without impairing responsiveness.
[0011]
[Means for Solving the Problems]
  In order to achieve the above object, the present invention transmits rotation from a rotating body that rotates in conjunction with a crankshaft of an internal combustion engine to a camshaft that drives a valve via each hydraulic chamber on the advance side and retard side. And a rotation phase changing means for changing a rotation phase between the rotating body and the camshaft in accordance with a hydraulic pressure supplied to the hydraulic chamber, and an oil pressure supplied to the hydraulic chamber of the rotation phase changing means in an engine operating state. Hydraulic pressure control means for controlling in accordance with the hydraulic pressure drop detection means for detecting a drop in the hydraulic pressure supplied to the hydraulic pressure chamber of the rotation phase change means,When the direction in which the cam shaft is moved by the rotational phase changing means coincides with the direction of action of the driving torque of the cam shaft, oil flows out of the hydraulic chamber.Oil outflow determining means for determining oil outflow from the hydraulic chamber of the rotational phase changing means when a decrease in oil pressure is detected and it is determined that oil will flow out of the hydraulic chamber of the rotational phase changing means And a control means for controlling the hydraulic pressure control means so as to reduce the pressure.
[0012]
FIG. 2 shows the pressure fluctuation in the hydraulic chamber (advanced hydraulic chamber and retarded hydraulic chamber) and the phase of the camshaft caused by fluctuations in the camshaft drive torque when the camshaft is moved from the advance side to the retard side. Showing fluctuations. The camshaft driving torque in FIG. 2 is positive when torque in the direction opposite to the rotation of the camshaft is generated. In order to move the camshaft from the advance side to the retard side, the retard hydraulic chamber is communicated with the oil pump via the hydraulic control means, and the advance hydraulic chamber is communicated with the oil discharge passage via the hydraulic control means. When the camshaft drive torque is positive, the hydraulic pressure in the advance hydraulic chamber is higher than the hydraulic pressure in the retard hydraulic chamber, and this differential pressure is balanced with the camshaft drive torque, but the advance hydraulic chamber communicates with the oil discharge passage. Since the oil flows out from the oil discharge passage, the hydraulic pressure in the advance hydraulic chamber rises slowly. However, the amount of oil flowing out from the advance hydraulic chamber causes a decrease in the volume of the advance hydraulic chamber, resulting in a large delay in the phase of the cam shaft. This camshaft phase lag is recovered when the hydraulic pressure in the advance hydraulic chamber becomes lower than the hydraulic pressure in the retard hydraulic chamber when the camshaft drive torque is negative. The phase variation width of the shaft is increasing. In order to improve the stability of the actual valve timing when the supply hydraulic pressure decreases, it is necessary to suppress the increase in the phase fluctuation range.
[0013]
The present invention controls the hydraulic pressure control means in accordance with the direction of camshaft movement and the direction of camshaft drive torque, and when moving the camshaft from the advance side to the retard side as in FIG. FIG. 3 shows the pressure fluctuation in the hydraulic chamber and the camshaft phase fluctuation caused by the fluctuation of the camshaft driving torque according to the present invention. In the region where the camshaft drive torque is negative, the retard hydraulic chamber is communicated with the oil pump via the hydraulic control means, and the advance hydraulic chamber is communicated with the oil discharge passage via the hydraulic control means, as in FIG. When the camshaft driving torque is positive, that is, when the camshaft driving torque is acting in the direction in which oil flows out of the advance hydraulic chamber of the rotation phase changing means, the amount of oil supply and oil discharge decreases. Control is made to a substantially fully closed position (near the holding duty ratio), and control is performed so that the oil outflow from the advance hydraulic chamber of the rotation phase change means is reduced, so that the oil in the advance hydraulic chamber flows out from the oil discharge passage. In order to suppress the amount of outflow to be reduced, even if the supply hydraulic pressure is reduced, an increase in the cam shaft phase fluctuation width due to a decrease in the volume of the advance hydraulic chamber can be suppressed.
[0014]
  Contrary to the above, an increase in the phase variation width of the cam shaft due to a decrease in the volume of the hydraulic chamber is also caused by a variation in the cam shaft driving torque when the cam shaft is moved from the retard side to the advance side. Also, when the camshaft drive torque acts in a direction that reduces the volume of the hydraulic chamber (retarding hydraulic chamber) communicating with the oil drain passage, control is performed so that the oil outflow from the retarding hydraulic chamber is reduced.YouJust do it.
  The hydraulic pressure outflow determining means of the present invention determines that oil flows out from the hydraulic chamber when the direction in which the camshaft is moved by the rotational phase changing means coincides with the operating direction of the camshaft driving torque.
[0015]
As a result, an increase in the cam shaft phase fluctuation width due to a decrease in the volume of the hydraulic chamber can be suppressed, and the stability of the actual valve timing can be improved.
[0016]
In the hydraulically driven valve timing adjusting device, the hydraulic pressure supplied from the oil pump decreases when the engine cooling water temperature is high and the engine rotation speed is low, so the engine cooling water temperature is equal to or higher than a predetermined value and the engine rotation speed is predetermined. By determining whether or not the value is less than or equal to the value, it is possible to detect a decrease in the hydraulic pressure in the hydraulic chamber of the rotation phase changing means.
[0017]
  Also,When the direction of moving the camshaft by the rotational phase changing means is opposite to the direction of operation of the driving torque of the camshaft, the control means supplies the hydraulic pressure supplied to the hydraulic chamber of the rotational phase changing means by the hydraulic control means. It can be controlled according to the operating state.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 5, the valve timing adjusting device of the present embodiment pumps oil to the rotation transmission member 11 using the rotation transmission member 11 attached to the intake side camshaft 12 and the driving force of the engine as a power source. An oil pump 15, an oil control valve (hydraulic control valve) 16 that changes the oil passage of oil pumped by the oil pump 15, and an electronic control circuit (ECU) 17 that controls the opening of the oil control valve are provided. Yes.
[0019]
The intake side camshaft 12 is rotatably supported between the upper end surface of the cylinder head 18 of the engine and the bearing cap 19, and a cam is formed on the outer periphery of the intake side camshaft 12. Each cam is in contact with the upper end of an intake valve provided for each cylinder of the engine, and the intake valve is opened and closed by rotating the cam together with the intake side camshaft 12.
[0020]
A large-diameter portion 21 is formed on a portion of the intake-side camshaft 12 that is pivotally supported by the cylinder head 18 and the bearing cap 19, and an annular driven gear is formed on the outer periphery of the large-diameter portion 21. 22 is rotatably mounted. A plurality of external teeth 22 a are formed on the outer peripheral portion of the driven gear 22, and the external teeth 22 a mesh with external teeth of a drive gear (not shown) attached to the exhaust side camshaft.
[0021]
The driven gear 22 and the drive gear engaged in this way are bridged by a timing belt on a crank pulley attached to the end of the crankshaft.
[0022]
The rotation transmitting member 11 includes a substantially hollow cylindrical housing 28 and a rotor 29 that is rotatably fitted in the housing 28. The housing 28 is fixed to the driven gear 22 with a bolt 30 together with a cover 38 that covers the rotor 29, and rotates together with the driven gear 22 together with the cover 38. Inside the housing 28, a plurality of protrusions protruding toward the axial center of the intake side camshaft 12 are formed at equal intervals, and the protrusions and the fixing portion of the rotor 29 are radially provided. As shown in FIG. 10, a plurality of advance hydraulic chambers 13 and retard hydraulic chambers 14 are formed by the same number of pressure receiving portions formed in the two. The rotor 29 is fixed to the intake side camshaft 12 by a mounting bolt 41 inserted in a center hole provided at the center of the fixing portion, and is engaged with the intake side camshaft 12 by a knock pin (not shown). It rotates integrally with the intake camshaft 12.
[0023]
Since the rotor 29 is rotatably inserted into the housing 28, the rotor 29 can rotate with the intake side camshaft 12 with respect to the housing 28, and has a rotational phase with respect to the housing 28 by this rotational angle. . Since the housing 28 rotates in synchronization with the crankshaft, this rotational phase is a rotational phase with respect to the crankshaft, and the position of the rotor 29 in the rotational direction relative to the housing 28, that is, the advance hydraulic chamber 13 and the retard hydraulic chamber 14. The rotational phase of the intake camshaft 12 relative to the crankshaft can be changed by adjusting the size. The rotation phase is changed by supplying oil from the oil control valve 16 through the advance side oil passage P1 and the retard side oil passage P2 communicating with the advance hydraulic chamber 13 and the retard hydraulic chamber 14 to advance the advance angle. This can be done by controlling the hydraulic pressure in the hydraulic chamber 13 and the retarded hydraulic chamber 14.
[0024]
A through hole 42 is formed in the pressure receiving portion of the rotor 29, and a bottomed cylindrical lock pin 43 is inserted into the through hole 42. A spring 48 is disposed inside the lock pin 43, and the lock pin 43 is always urged toward the driven gear 22 side. An engagement hole 49A into which the lock pin 43 can be inserted is formed at a position corresponding to the lock pin 43 on the rotor 29 side of the driven gear 22, and by inserting the lock pin 43 into the engagement hole 49A, the rotor 29 The rotational phase can be fixed on the maximum advance side.
[0025]
The oil pump 15 is a pump that operates using the driving force of the engine as a driving source, and pumps oil stored in the oil pan 57 to the oil control valve 16. An oil filter 55 that removes foreign matters in the oil is provided between the oil pump 15 and the oil control valve 16.
[0026]
The oil control valve 16 includes a casing 70, a spool 76 fitted in the casing 70, an electromagnetic solenoid 78 that drives the spool 76 in the axial direction, and a spring 79 that biases the spool 76 toward the electromagnetic solenoid 78. I have. The casing 70 includes an advance angle side port 71 connected to the advance angle side oil path P1, an advance angle side drain port 72 that discharges oil flowing from the advance angle side oil path P1 to the oil pan 57, and a retard angle side. The retarded-side port 73 connected to the oil passage P2, the retarded-side drain port 74 for discharging the oil flowing from the retarded-side oil passage P2 to the oil pan 57, and the oil pump 15 via the oil filter 55 An inflow port 75 which is an inflow port for the oil to be formed is formed.
[0027]
The spool 76 is formed with valve bodies 77 at positions where the advance angle side port 71 and the retard angle side port 73 can be closed simultaneously, and the advance angle side drain port 72 and the retard angle side drain port 74 are opened. As shown, valve bodies 77 are formed on both sides. Accordingly, the spool 76 is moved so that the inflow port 75 and the retard side port 73 communicate with each other, and the advance side port 71 and the advance side drain port 72 communicate with each other via the retard side oil passage P2. Thus, oil can be supplied to the retard hydraulic chamber 14 and discharged from the advance hydraulic chamber 13 via the advance oil passage P1, so that the rotor 29 can be rotated to the retard side. On the contrary, the spool 76 is moved to connect the inflow port 75 and the advance side port 71 and the retard side port 73 and the retard side drain port 74 are connected to each other via the advance side oil passage P1. Thus, oil can be supplied to the advance hydraulic chamber 13 and discharged from the retard hydraulic chamber 14 via the retard oil passage P2, and the rotor 29 can be rotated to the advance side. The spool 76 stops at a position where the urging force by the spring 79 and the urging force against the urging force of the spring 79 by the electromagnetic solenoid 78 are balanced. The position can be controlled.
[0028]
Connected to the ECU 17 are a rotation speed sensor 66 for detecting the engine rotation speed, an air flow meter 67 for detecting the intake air amount, a crank angle sensor 68 for detecting the crankshaft angle, and a cam angle sensor 69 for detecting the camshaft angle. Has been.
[0029]
A rotational speed sensor 66 and an air flow meter 67 connected to the ECU 17 detect the engine rotational speed and the intake air amount, respectively. Further, the ECU 17 calculates a target advance amount of the camshaft 12 that matches the operating state of the engine based on detection signals input from the crank angle sensor 68 and the cam angle sensor 69 connected to the ECU 17. At the same time, the actual advance amount of the camshaft 12 is detected. Then, the ECU 17 controls the duty ratio of the oil control valve 16 so that the deviation between the actual advance angle amount of the cam shaft 12 and the target advance angle amount becomes a predetermined value or less.
[0030]
When the electromagnetic solenoid 78 is driven at a duty ratio of 100% by the ECU 17, the position of the spool 76 is set to the advance position. Thereby, the advance side oil passage P1 is connected to the discharge side of the oil pump 15 via the inflow port 75 and the advance side port 71, and the retard side oil passage P2 is connected to the retard side port 73 and the retard side drain. It is connected to the oil pan 57 via the port 74. As a result, oil is supplied into each advance hydraulic chamber 13 through the advance side oil passage P1. On the other hand, the oil in each retarded hydraulic chamber 14 is returned to the oil pan 57 through the retarded oil passage P2.
[0031]
Further, when the electromagnetic solenoid 78 is driven with a duty ratio of 0% (stop of energization control for the solenoid), the position of the spool 76 is set to the retard position. As a result, the retard side oil passage P <b> 2 is connected to the discharge side of the oil pump 15 via the inflow port 75 and the retard side port 73. On the other hand, the advance side oil passage P <b> 1 is connected to the oil pan 57 via the advance side port 71 and the advance side drain port 72. As a result, oil is supplied into each retarded hydraulic chamber 14 through the retarded oil passage P2. On the other hand, the oil in each advance hydraulic chamber 13 is returned to the oil pan 57 through the advance side oil passage P1.
[0032]
Further, when the electromagnetic solenoid 78 is driven at a duty ratio (hereinafter referred to as a holding duty ratio) that minimizes the oil supply amount and the oil discharge amount of about 50%, the position of the spool 76 can be held at the holding position. . Thereby, the valve body 77 of the spool 76 closes the advance side port 71 and the retard side port 73. As a result, oil is not supplied to or discharged from the advance hydraulic chamber 13 and the retard hydraulic chamber 14, and the hydraulic pressure in the advance hydraulic chamber 13 and the retard hydraulic chamber 14 is maintained in the current state.
[0033]
With reference to FIG. 6, the process routine of ECU17 of this Embodiment is demonstrated. This routine is repeatedly executed at a predetermined time period. First, in step 110, the output of the engine speed sensor is input, the current engine speed is detected based on the output of the speed sensor, and various air flow meter output, crank angle sensor output, cam angle sensor output, etc. Capture sensor output. In step 120, an optimal target advance amount r corresponding to each of the signals indicating the engine operating state is calculated based on a map stored in advance. This map is created and stored in advance based on the engine coolant temperature, the engine speed, the intake air amount, and the like.
[0034]
In the next step 130, the actual advance amount y of the cam shaft 12 is calculated based on the pulse signals from the crank angle sensor 68 and the cam angle sensor 69. In step 140, the driving duty ratio of the valve timing driving device is calculated. This drive duty ratio is a duty ratio for controlling the actual advance amount y to the target advance amount r, and the difference between the actual advance amount y and the target advance amount r using a preset arithmetic expression. Is calculated based on
[0035]
In the next step 150, it is determined whether or not the hydraulic pressure has decreased by determining whether or not the hydraulic pressure decrease flag F is set (F = 1). This oil pressure reduction flag F is set and reset by a hydraulic pressure reduction diagnosis routine which will be described later. When the oil pressure reduction flag F is not set, the drive duty ratio calculated in step 140 is output to the electromagnetic solenoid 78 in step 160. As a result, the electromagnetic solenoid 78 is driven in accordance with the drive duty ratio, the spool 76 is controlled to a position in accordance with the drive duty ratio, and the supply amount of oil fed by the oil pump 15 to the valve timing adjusting device and the oil pan are controlled. The outflow amount to 57 is adjusted. Thereby, the rotation angle of the camshaft 12 is fed back to the optimum target advance amount in accordance with the operating state of the engine.
[0036]
On the other hand, when the oil pressure drop flag F is set in step 150, a low oil pressure control routine described later is executed in step 170. This routine is repeatedly executed at a predetermined time period.
[0037]
The hydraulic pressure supplied from the oil pump to the valve timing adjusting device is substantially determined according to the engine speed and the engine temperature. Therefore, in the oil pressure reduction diagnosis routine of FIG. 7, the engine coolant temperature is compared with a predetermined first predetermined value, and the engine rotation speed is compared with a predetermined second predetermined value. It is determined that the hydraulic pressure supplied from the oil pump to the valve timing adjusting device has decreased when the engine speed is equal to or higher than the predetermined value and the engine speed is equal to or lower than the second predetermined value.
[0038]
Hereinafter, the hydraulic pressure drop diagnosis routine of FIG. 7 will be described. First, in step 210, it is determined whether or not the hydraulic pressure has decreased by determining whether or not the detected engine coolant temperature is equal to or higher than a predetermined value. If the engine coolant temperature is less than the predetermined value, it is determined that the hydraulic pressure has not decreased, and the hydraulic pressure decrease flag F is reset in step 240. On the other hand, if the engine coolant temperature is equal to or higher than the predetermined value, it is determined in step 220 whether the engine speed is equal to or lower than the predetermined value. If the engine speed exceeds the predetermined value, it is determined that the oil pressure has not decreased, and the oil pressure decrease flag F is reset in step 240. If the engine speed is less than the predetermined value, the oil pressure decreases. In step 230, the hydraulic pressure reduction flag F is set.
[0039]
Next, the details of the low hydraulic pressure control routine in step 170 will be described. In this routine, when the oil pressure supplied from the oil pump to the valve timing adjusting device decreases, the direction in which the camshaft 12 is moved to the target advance amount coincides with the drive torque generated in the camshaft 12. In other words, when the camshaft drive torque acts in a direction that reduces the volume of the hydraulic chamber communicating with the oil drainage passage, the oil control valve is set to a substantially fully closed position (near the holding duty ratio) where the amount of oil supply and oil draining decreases. ) Is controlled so as to reduce the outflow of oil from the hydraulic chamber. On the other hand, when the hydraulic pressure supplied from the oil pump to the valve timing adjusting device decreases, the direction in which the camshaft is moved to the target advance amount and the drive torque generated on the camshaft are opposite, that is, the oil pump When the camshaft driving torque acts in the direction in which the volume of the hydraulic chamber communicating with the valve decreases, the valve timing is changed. As a result, an increase in the cam shaft phase fluctuation width due to a decrease in the volume of the hydraulic chamber is suppressed, and the stability of the actual valve timing is improved.
[0040]
Hereinafter, the low hydraulic pressure control routine of FIG. 8 will be described. First, in step 310, the direction of movement of the camshaft is determined by comparing the target advance amount r and the actual advance amount y. In other words, if the target advance angle amount r> the actual advance angle amount y, it is determined that the advance angle should be advanced, and it is determined in step 320 whether or not it is in the positive torque range. On the other hand, if the target advance angle amount r <the actual advance angle amount y, it is determined that the angle should be retarded, and it is determined in step 350 whether or not it is in the negative torque range.
[0041]
The camshaft drive torque varies periodically with respect to the cam angle depending on the load of the valve spring and the inertial force of the reciprocating parts. However, when the engine speed is low, the load of the valve spring becomes the camshaft drive torque. On the other hand, it becomes dominant and fluctuates sinusoidally as shown in FIG. For this reason, if data indicating whether the cam shaft driving torque is in the positive torque range or the negative torque range with respect to the cam angle shown in FIG. 2 is stored in the ECU 17 in advance, the cam angle sensor 69 or the crank angle sensor 68 detects the data. It is possible to determine whether the torque range is positive torque range or negative torque range.
[0042]
If it is determined in step 320 that positive torque is acting on the camshaft from the detected cam angle, that is, in the positive torque range, the drive duty ratio calculated in step 140 in step 330 is set to oil control. If it is in the negative torque range, it outputs to the valve, and in step 340, the duty ratio that reduces the oil supply amount and the oil discharge amount is output. Here, as shown in FIG. 9, the duty ratio at which the oil supply amount and the oil discharge amount are reduced is an oil control valve whose duty ratio (holding duty ratio) at which the oil supply amount and the oil discharge amount are minimized is 50%. Indicates a range of holding duty ratio (50%) ± 10%. Generally, holding duty ratio ± It may be about 10%.
[0043]
On the other hand, if negative torque is acting on the camshaft in step 350 and it is determined that the torque is in the negative torque range, the drive duty ratio calculated in step 140 in step 360 is output to the oil control valve, and in the positive torque range. If there is, in step 340, a duty ratio that reduces the oil supply amount and the oil discharge amount is output.
[0044]
As described above, according to the present embodiment, in the engine operating state in which the hydraulic pressure supplied from the oil pump decreases, the valve timing is only when the direction of moving the camshaft and the direction of the camshaft driving torque are opposite. When the camshaft moving direction matches the camshaft drive torque direction, the oil control valve should be set to the fully closed position where the oil supply amount and oil discharge amount are reduced. I have control. As a result, oil can be prevented from flowing out of the hydraulic chamber where the pressure should be increased in order to balance the camshaft drive torque, and the phase fluctuation range of the camshaft can be reduced without impairing the responsiveness of the valve timing adjusting device. it can.
[0045]
FIG. 4 shows the phase fluctuation width of the cam shaft when moving toward the retard side and when moving toward the advance side, comparing the conventional examples A and B with the present embodiment. In this embodiment, the oil outflow amount is held and controlled when the camshaft drive torque is positive when moving to the retard side, and the oil outflow amount is held when the cam drive torque is negative when moving to the advance side. Therefore, the oil outflow amount is held and controlled when the camshaft drive torque is negative when moving to the retard side, and the oil outflow amount is held when the cam drive torque is positive when moving to the advance side. Conventional example B in which the cam shaft phase fluctuation width is much smaller than that in the conventional example B to be controlled, and the conventional camshaft phase fluctuation width is smaller than that in the conventional example B. Compared with the control method), the cam shaft phase fluctuation width is halved.
[0046]
In the above description, the embodiment in which the present invention is applied to a so-called rotor type valve timing adjusting device has been described. However, the present invention can also be applied to a helical gear type valve timing adjusting device as long as it is hydraulically driven.
[0047]
【The invention's effect】
As described above, according to the present invention, since a decrease in oil pressure is detected and it is determined that oil flows out from the hydraulic chamber, the oil outflow from the hydraulic chamber is reduced. The oil can be prevented from flowing out of the hydraulic chamber where the pressure should be increased in order to balance the pressure, and the cam shaft phase fluctuation width can be reduced without impairing the responsiveness of the valve timing adjusting device. .
[Brief description of the drawings]
FIG. 1 is a diagram showing a relationship between a supply pressure to a valve timing adjusting device and a cam shaft phase fluctuation range;
FIG. 2 is a diagram showing changes in cam shaft drive torque, retard hydraulic chamber hydraulic pressure, advance hydraulic chamber hydraulic pressure, and cam shaft phase with respect to the cam angle when the cam shaft is moved from the advance side to the retard side. is there.
FIG. 3 is a diagram showing changes in cam shaft driving torque, retard hydraulic chamber hydraulic pressure, advance hydraulic chamber hydraulic pressure, and cam shaft phase with respect to the cam angle when the cam shaft is moved from the retard side to the advance side. is there.
FIG. 4A is a diagram comparing the cam shaft phase fluctuation widths of the conventional example A, the conventional example B, and the present embodiment when the rotation transmitting member is moving to the retard side; (B) is a diagram showing comparison between camshaft phase fluctuation widths of the conventional example A, the conventional example B, and the present embodiment when the rotation transmitting member moves to the advance side.
FIG. 5 is a schematic diagram of a valve timing adjusting device of the present embodiment.
FIG. 6 is a flowchart showing a main routine of the present embodiment.
FIG. 7 is a flowchart showing a hydraulic pressure reduction diagnosis routine according to the present embodiment.
FIG. 8 is a flowchart showing a drive duty ratio control routine at the time of low oil pressure according to the present embodiment.
FIG. 9 is a diagram showing a relationship between a drive duty ratio, an oil supply amount, and an oil discharge amount.
FIG. 10 is a schematic view of an advance hydraulic chamber and a retard hydraulic chamber of the valve timing adjustment device of the present embodiment.
[Explanation of symbols]
11 Rotation transmission member
12 Inlet camshaft
13 Advance hydraulic chamber
14 Delayed hydraulic chamber
15 Oil pump
16 Oil control valve
28 Housing
29 Rotor
57 oil pan
70 casing
76 spools
77 Disc
78 Electromagnetic solenoid

Claims (3)

The rotation is transmitted from the rotating body that rotates in conjunction with the crankshaft of the internal combustion engine to the camshaft that drives the valve via the hydraulic chambers on the advance side and the retard side, and the hydraulic pressure supplied to the hydraulic chamber A rotation phase changing means for changing a rotation phase between the rotating body and the camshaft,
Hydraulic control means for controlling the hydraulic pressure supplied to the hydraulic chamber of the rotational phase changing means according to the engine operating state;
A hydraulic pressure drop detecting means for detecting a drop in the hydraulic pressure supplied to the hydraulic chamber of the rotational phase changing means;
Oil outflow determining means for determining that oil flows out of the hydraulic chamber when the direction in which the camshaft is moved by the rotation phase changing means and the direction of action of the driving torque of the camshaft coincide ;
Oil pressure control means so that the oil outflow from the hydraulic chamber of the rotation phase change means is reduced when a decrease in oil pressure is detected and it is determined that oil flows out of the hydraulic chamber of the rotation phase change means Control means for controlling
A valve timing adjusting device for an internal combustion engine, including: The hydraulic pressure drop detecting means detects a drop in hydraulic pressure in a hydraulic chamber of the rotation phase changing means by determining whether or not the engine coolant temperature is equal to or higher than a predetermined value and the engine rotational speed is equal to or lower than a predetermined value. 2. A valve timing adjusting device for an internal combustion engine according to 1. When the direction of moving the camshaft by the rotational phase changing means is opposite to the direction of operation of the driving torque of the camshaft, the control means causes the hydraulic chamber of the rotational phase changing means by the hydraulic control means. The valve timing adjusting device for an internal combustion engine according to claim 1 or 2 , wherein the hydraulic pressure supplied to the engine is controlled in accordance with an engine operating state .

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