JP2016166570A - Variable valve timing device of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the deterioration of a holding property of a control rotation phase by the rocking movement of a rotor vane when a driving load of a cam shaft is varied.SOLUTION: A variable valve timing device of an engine supplies control oil pressure into either one of an advance actuation chamber 307 composed of a housing 301 driven by a crank shaft of an engine and a rotor vane 302 fixed to the cam shaft or a delay actuation chamber 309, thereby controlling a rotation phase of the cam shaft. At a part on the opposite side of the either one of the advance actuation chamber 307 or the delay actuation chamber 309, a drain chamber 308 is formed across the rotor vane 302. The drain chamber 308 is provided with an oil drain hole 320 communicating with the outside, in an inner side part in a radial direction of the housing 301, so as to generate an oil reservoir Von an outer side part in the radial direction during actuation.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a variable valve timing device for an engine.

  Patent Document 1 discloses an air vent hole that smoothly unlocks a lock pin that locks a rotor vane fixed to a camshaft at the most retarded position and the most advanced position of a hydraulic variable valve timing (VVT) device. A technique is disclosed in which is arranged inside the working chamber in the radial direction.

  In the hydraulic VVT device, a plurality of advance working chambers and retard working chambers constituted by a housing driven by a crankshaft and a rotor vane fixed to the camshaft, and oil for discharging oil to the outside of the housing And a drain chamber having a drain hole, and the oil flowing into the drain chamber is discharged to enhance the operation response of the hydraulic VVT device.

JP 2009-215965 A

  However, the hydraulic VVT device is controlled so as to have a predetermined rotation phase angle in the low rotation region of the engine (hereinafter also referred to as “control rotation phase”). When drive load fluctuations occur, the rotor vane repeats a swinging movement due to the influence, and when the adjacent working chamber becomes negative pressure for a moment, the air in the drain chamber flows into the adjacent working chamber. As a result of repeated compression with respect to the inflowing air, there is a problem that the holding property for holding the camshaft at a predetermined control rotation phase deteriorates.

  The present invention has been made in view of such a point, and the problem is that the rotor vanes oscillate when the camshaft drive load fluctuates, and the control rotation phase retainability decreases particularly in the low rotation region. It is an object of the present invention to provide a variable valve timing device for an engine that can suppress the above.

  In order to solve the above problems, the present invention is characterized in that an oil drain hole in a drain chamber for draining oil provided in a housing of a variable valve timing device is provided in an inner portion in a radial direction of the housing.

  Specifically, the present invention is directed to a variable valve timing device for an engine, and the following solution is taken.

  That is, according to the first aspect of the present invention, the control hydraulic pressure is supplied to either the advance working chamber or the retard working chamber composed of a housing driven by the crankshaft of the engine and a rotor vane fixed to the camshaft. Targeted for engine variable valve timing devices that control the rotational phase of the camshaft, a drain chamber is formed on either side of either the advance working chamber or the retard working chamber with a rotor vane in between. In the drain chamber, an oil drain hole communicating with the outside is provided in the radially inner portion so that an oil reservoir is generated in the radially outer portion of the housing when the engine is operated.

  According to this, since a predetermined amount of oil is stored in the drain chamber driven by the cam when the engine is operated, the rotor vane oscillates when the driving load of the camshaft fluctuates, so Even if the angular working chamber becomes negative pressure, the air in the drain chamber does not flow into the advance working chamber or the retard working chamber through the gap between the seal members of the rotor vanes. As a result, it is possible to suppress a decrease in the holding property of the control rotation phase due to the elasticity of the air flowing into the hydraulic variable valve timing device in the low rotation range.

  In a second aspect based on the first aspect, a seal member is provided on a sliding surface of the rotor vane that slides with the housing, and the oil sump is at least the height of the seal member in the radial direction of the housing. Of oil.

  According to this, since at least oil corresponding to the height in the radial direction of the housing in the seal member is accumulated in the oil sump during the operation of the engine, the advance angle from the clearance of the seal member provided in the rotor vane that defines the drain chamber. Since air does not leak into the working chamber or the retarded working chamber, it is possible to more reliably suppress a decrease in the holding property of the control rotation phase.

  According to a third invention, in the first or second invention, the drain chamber, the plurality of advance working chambers, and the plurality of retard working chambers are formed by the housing and the rotor vane. .

  According to this, it is possible to achieve both the operation responsiveness of the rotational phase control and the retention of the control rotational phase by one drain chamber and a plurality of advance working chambers and retard working chambers.

  According to a fourth aspect of the present invention, in the first to third aspects of the present invention, an auxiliary machine driven by a cam portion of the cam shaft is further provided.

  According to this, even when the load fluctuation of the camshaft becomes large due to the driving load of the auxiliary machine, it is possible to suppress a decrease in control rotation phase holding ability.

  According to a fifth aspect, in the fourth aspect, the engine includes a turbocharger, and the auxiliary device is a high-pressure fuel pump of a fuel supply system that injects fuel into a combustion chamber of the engine. .

  According to this, even when the driving load of the high-pressure fuel pump is large, it is possible to suppress a decrease in the control rotation phase retention in the hydraulic variable valve timing device.

  According to the present invention, it is possible to suppress the lowering of the control rotation phase retention particularly in the low rotation region due to the swinging motion of the rotor vanes when the camshaft drive load fluctuates.

FIG. 1 is a partial sectional view showing a schematic configuration of an engine provided with a hydraulically operated variable valve timing device according to an embodiment of the present invention. FIG. 2 is a schematic side view of an engine showing a high-pressure fuel pump and the like as an example of an auxiliary machine driven together with the variable valve timing device according to the embodiment of the present invention. FIG. 3 is a cross-sectional view in a direction perpendicular to the camshaft at the most advanced angle position of the rotor vane in the variable valve timing device according to the embodiment of the present invention. FIG. 4 is a cross-sectional view in a direction perpendicular to the camshaft at the most retarded position of the rotor vane in the variable valve timing device according to the embodiment of the present invention. FIG. 5 is a schematic cross-sectional view taken along the line VV in FIG. FIG. 6 is a sectional view in the axial direction of the cam shaft in the variable valve timing device according to the embodiment of the present invention. FIG. 7 is a cross-sectional view in a direction perpendicular to the camshaft at the most advanced position of the rotor vane in the variable valve timing device according to the comparative example. FIG. 8 is a cross-sectional view in the direction perpendicular to the camshaft at the most retarded position of the rotor vane in the variable valve timing device according to the comparative example. FIG. 9 is a graph showing the results of measuring the holding performance of the predetermined angle (15 CA) of the camshaft together with the comparative example in the variable valve timing device according to the embodiment of the present invention by changing the rotation speed. FIG. 10 is a graph showing the result of measuring the retention of the predetermined angle (35CA) of the camshaft together with the comparative example in the variable valve timing device according to the embodiment of the present invention by changing the rotation speed. FIG. 11 is a cross-sectional view in a direction perpendicular to the camshaft at the most advanced position of the rotor vane in the variable valve timing device according to the modification of the embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the invention, its application, or its application. In addition, the ratio of dimensions between the constituent members in the drawings is partially enlarged or reduced for easy understanding, and is different from the actual scale.

(One embodiment)
FIG. 1 shows an engine 2 provided with a hydraulically operated variable valve timing device according to an embodiment of the present invention. The engine 2 is, for example, an in-line four-cylinder gasoline engine and is mounted on a vehicle such as an automobile. The engine 2 is configured by vertically connecting a cam cap 3, a cylinder head 4, a cylinder block 5, a crankcase (not shown), and an oil pan (not shown). Further, a piston 8 slidable in each of four cylinder bores 7 formed in the cylinder block 5 and a crankshaft 9 rotatably supported by the crankcase are connected by a connecting rod 10. A combustion chamber 11 is formed for each cylinder by the cylinder bore 7, the piston 8, and the cylinder head 4.

  The cylinder head 4 is provided with an intake port 12 and an exhaust port 13 that open to the combustion chamber 11, and an intake valve 14 and an exhaust valve 15 that open and close the intake port 12 and the exhaust port 13, respectively. Each is equipped. The intake valve 14 and the exhaust valve 15 are urged in the closing direction (upward in the figure) by return springs 16 and 17, respectively. For example, cam followers 20a and 21a that are rotatably provided at substantially central portions of the swing arms 20 and 21 are pushed downward by cam portions (cam noses) 18a and 19a provided on the outer circumferences of the rotating cam shafts 18 and 19, respectively. Then, the swing arms 20 and 21 swing around the top of the pivot mechanism 25a provided on one end side of the swing arms 20 and 21 as a fulcrum. As a result, the intake valve 14 and the exhaust valve 15 are opened by being pushed downward against the urging force of the return springs 16 and 17 at the other end of the swing arms 20 and 21. It is configured.

  As shown in FIG. 2, the engine 2 is provided with a high-pressure fuel pump 6 such as a plunger-type reciprocating pump driven by an exhaust-side camshaft 19, for example. The pump 6 is a fuel supply system pump that injects fuel into each combustion chamber. For example, a vane type vacuum pump 22 is provided at the side of the high-pressure fuel pump 6.

  Although not shown, the engine 2 is equipped with a turbocharger that supercharges the intake air by the kinetic energy of the exhaust, and the fuel via the high-pressure fuel pump 6 is shown in FIG. It is injected directly into each combustion chamber 11 shown.

  Next, a hydraulically operated variable valve timing device 30 (hereinafter referred to as a VVT device 30) according to the present embodiment will be described with reference to FIGS. In the present embodiment, the VVT device 30 is connected to, for example, the exhaust-side camshaft 19, and in FIG. 3, the VVT device 30 is controlled so that the displacement of the rotational phase of the cam portion 19a becomes the most advanced position. FIG. 4 shows a state in which the VVT device 30 is controlled so that the displacement of the rotational phase of the cam portion 19a is at the most retarded position.

  As shown in FIGS. 3 and 4, the VVT device 30 according to the present embodiment includes a substantially annular housing 301 and a rotor vane 302 accommodated in the housing 301. The rotor vane 302 includes a rotor main body 302a constituting a central portion of the rotating body and four vane bodies 302b protruding from the rotor main body 302a to the outer peripheral surface thereof. As a sliding portion with respect to the housing 301 in each vane body 302b, a seal member 324 for oil seal is provided in a groove formed in the width direction of the vane body 302b (see FIG. 5).

  The housing 301 is connected to a sprocket 303 that rotates in synchronization with the crankshaft 9 so as to rotate integrally therewith, and rotates in conjunction with the crankshaft 9. The rotor vane 302 is connected to the camshaft 19 for opening and closing the exhaust valve 15 and a bolt 205 (see FIG. 6) so as to be integrally rotatable.

  A plurality of advance working chambers 307 and retard working chambers 309 defined by the inner peripheral surface of the housing 301 and the rotor vane 302 are formed inside the housing 301.

  The camshaft 19 and the rotor vane 302 are provided with an advance side oil passage 311 and a retard side oil passage 312 for supplying oil (engine oil) to the advance working chamber 307 and the retard working chamber 309, respectively. The oil passages 311 and 312 provided in the camshaft 19 are supplied with controlled oil via a solenoid valve (not shown).

  As shown in FIG. 3, the advance side oil passage 311 is connected to two advance angle working chambers 307 that extend radially from two portions in the vicinity of the central portion of the rotor main body 302 a of the rotor vane 302 and face each other. . Here, one advance working chamber 307 on the rotational direction side of the sprocket 303 from a lock pin 331 (to be described later) in the plurality of advanced working chambers 307 and another advance working chamber 307 located on the rotational direction side thereof. These are communicated by a concave oil passage 311 a provided on the inner wall of the housing 301.

  On the other hand, as shown in FIGS. 3 and 4, the retard angle side oil passage 312 extends radially from the other two portions in the vicinity of the central portion of the rotor main body 302a, and two retard angle working chambers 309 facing each other. Connected. Here, the remaining two retarded-side oil passages 312 in which no oil supply port is provided are connected to the bolt 205 shown in FIG. 6 through a recess provided in the neck portion. One of the four retarded oil passages 312 is formed at a position where the vane body 302b is not formed on the outer peripheral surface of the rotor main body 302a at the most advanced position, and a lock pin 331 described later is fitted. It connects with the bottom face of the fitting recessed part 302c to match.

  The VVT device 30 according to the present embodiment is provided with a lock pin 331 that locks the operation of the VVT device 30. The lock pin 331 fixes the phase angle of the camshaft 19 with respect to the crankshaft 9 at a specific phase angle. In the present embodiment, the specific phase angle is the most advanced angle, but is not limited thereto, and may be any phase angle. In the present embodiment, as an example, after the engine 2 is operated, the lock pin 331 is disengaged from the fitting recess 302c by hydraulic pressure.

  For example, as shown in FIG. 4, when oil is supplied to the retarded working chamber 309 with a larger supply amount (higher hydraulic pressure) than the advanced working chamber 307, each vane body 302b receives the hydraulic pressure, whereby the camshaft 19 (rotor main body 302a) rotates in the direction opposite to the rotation direction with respect to the housing 301 (crankshaft 9). For this reason, the opening timing of the exhaust valve 15 is delayed. On the other hand, as shown in FIG. 3, when oil is supplied to the advance working chamber 307 with a larger supply amount (higher hydraulic pressure) than the retard working chamber 309, the camshaft 19 rotates in its rotational direction. Thus, the opening timing of the exhaust valve 15 is advanced.

  By the way, when the rotational phase angle of the cam shaft 19 is to be changed, for example, from the most advanced position in FIG. 3 to the most retarded position in FIG. Changes cannot be made quickly. For example, when changing the rotor vane 302 from the most advanced position to the most retarded position all at once, oil is supplied to the four retarded side oil passages 312 with a predetermined hydraulic pressure, and the retarded working chamber 309 is filled with oil. On the other hand, it is necessary to extract oil from the two advance side oil passages 311.

  Therefore, in the present embodiment, as shown in FIG. 3, for example, the lock pin 331 is positioned on the opposite side to the rotation direction of the sprocket 303, and is partitioned by the inner peripheral surface of the housing 301 and the rotor vane 302. One drain chamber 308 is provided to quickly extract oil (oil pan) that is unnecessary for changing the phase angle to the outside (oil pan). The position where the drain chamber 308 is provided is not limited to the above, and the drain chamber 308 may be provided at a position opposite to one of the advance working chamber 307 and the retard working chamber 309 and at a position sandwiching the vane body 302b of the rotor vane 302. it can.

  As shown in FIGS. 3 and 4, the drain chamber 308 is provided with one oil drain hole 320 in the vicinity of the radially inner side of the housing 301. Further, as shown in FIG. 4, the oil drain hole 320 is provided at a position where the vane body 302b is not blocked even when the vane body 302b is at the most retarded position.

  7 and 8 show a cross-sectional configuration of the VVT device 34 according to the comparative example. The difference from the VVT device 30 according to this embodiment shown in FIGS. 3 and 4 is that the arrangement position of the oil drain hole 320 provided in the drain chamber 308 is provided in the radially outer portion of the housing 301. An oil drain hole 322 is provided. The other structural members are the same, and are given the same reference numerals.

  As shown in FIGS. 9 and 10, the inventors of the present application measured retention of a predetermined control angle of the cam shaft in the comparative example and this embodiment.

  In FIG. 9, in both the comparative example and the present embodiment, the holding phase angle is 15 CA (crank angle), the engine speed is 850 rpm and 1250 rpm, and the hydraulic pressure supplied to the VVT devices 30 and 34 is The relatively low 45 kPa. In FIG. 10, in both the comparative example and the present embodiment, the holding phase angle is 35 CA (crank angle), the engine speeds are 850 rpm and 1250 rpm, and the hydraulic pressure supplied to the VVT devices 30 and 34 is 45 kPa. It is said.

  When the predetermined holding phase angle shown in FIG. 9 is 15 CA, the VVT device 30 according to the present embodiment is compared with the VVT device 34 according to the comparative example when the engine speed is 850 rpm and 1250 rpm. However, it can be seen that the phase fluctuation is clearly small, and the rotational phase retention by the control is good.

  On the other hand, when the predetermined holding phase angle shown in FIG. 10 is 35 CA, the amplitude of the phase fluctuation is not greatly changed.

  Hereinafter, the reason why the rotational phase angle retention in the VVT device 34 according to the comparative example is not good and the reason why the rotational phase angle retention in the VVT device 30 according to the present embodiment is good will be described.

  In the case of the VVT device 34 according to the comparative example shown in FIGS. 7 and 8, since the oil drain hole 322 of the drain chamber 308 is provided in the radially outer portion of the housing 301, the housing 301 is rotated ( When the camshaft 19 rotates), the oil in the drain chamber 308 flows out from the oil drain hole 322 by the centrifugal force. Thereby, for example, in the most advanced angle position of the rotor vane 302 shown in FIG. 7, the retarded working chamber 309 generated when the vane body 302 b that defines the drain chamber 308 swings on the opposite side of the rotation direction of the housing 301. Due to the negative pressure, air flows from the gap between the seal member 324 attached to the vane body 302b and the housing 301 into the retarded working chamber 309 having a negative pressure. It is considered that the inflow of air having a bulk modulus smaller than that of oil increases the amplitude of oscillation generated in the vane body 302b, and the retention of the rotational phase angle is not good.

On the other hand, as shown in FIG. 3, in the VVT device 30 according to the present embodiment, the oil drain hole 320 of the drain chamber 308 causes the oil reservoir V _{0 to} be generated in the radially outer portion of the housing 301. In addition, it is provided in the radially inner portion of the housing 301. The oil reservoir V _0, the seal member 324 is attached to the vane body 302b is, with volume enough to soak in remaining oil. Thereby, even when the vane body 302b constituting the drain chamber 308 swings in the opposite direction of the rotation direction of the housing 301, the inflow of air into the retarded working chamber 309 having a negative pressure is prevented. Can do. In addition, the flow of oil into the retarded working chamber 309 that has become negative pressure is very small, and even if it flows, the volume change due to the rocking pressure can be ignored.

Here, as shown in FIG. 4, in the most retarded state of the rotor vane 302, when the oil drain hole 320 of the drain chamber 308 is provided at the innermost side in the radial direction of the housing 301, the volume of the oil reservoir V ₁ is increased. Maximum. The oil reservoir oil collected in V ₁ was in the V ₀ oil sump in the most advanced state shown in FIG. 3, at least the seal member 324 the amount of only soaked in the oil is ensured.

  In addition, when the holding phase angle is 35 CA, the effect of this embodiment is not clear. When the rotational phase angle becomes relatively large, the oil passages 311 and 312 are completely opened, and the advance working chamber 307 or This is because the supply of oil to the retarded working chamber 309 increases. As a result, oil leakage from the working chambers 307 and 309 to the drain chamber 308 increases, so in the comparative example, for example, the inflow of oil from the drain chamber 308 to the retarded working chamber 309 increases. It is considered that the inflow of air from the drain chamber 308 to the retarded working chamber 309 is suppressed.

  Moreover, even if it is the structure which provides the oil drain hole 320 inside the radial direction of the housing 301 like this embodiment, the operation responsiveness (oil discharge | emission performance) of the rotor vane 302 is comparable as a comparative example. I have confirmed that.

  In the present embodiment, as shown in FIG. 2, a high-pressure fuel pump 6 that injects fuel in the combustion chamber 11 of the engine 2 as an auxiliary machine is attached to the engine 2. As described above, the high-pressure fuel pump 6 is driven by the exhaust-side camshaft 19, and even if the driving load is relatively large, the holdability of the controlled predetermined rotational phase angle is reduced. Can be suppressed.

  In this embodiment, the VVT device 30 is provided on the exhaust-side camshaft 19, but may be provided on the intake-side camshaft 18. Further, the camshafts 18 and 19 on both the intake side and the exhaust side can be provided and controlled independently.

-Effect-
As described above, according to the present embodiment, in order to improve the control responsiveness of the rotor vane 302 in the VVT device 30, for example, one of the four advance working chambers 307 is drained from the drain chamber 308. It is said. Further, an oil drain hole 320 of the drain chamber 308 is provided in the radially inner portion of the housing 301 so that an oil reservoir V ₀ is generated in the radially outer portion of the housing 301. The oil reservoir V ₀ has a volume that allows the seal member 324 attached to the vane body 302 b to be immersed in the oil. As a result, the swing of the vane body 302b that defines the drain chamber 308 prevents air from flowing into the retarded working chamber 309 adjacent to the drain chamber 308 and the vane body 302b with the gap between the seal members 324 interposed therebetween. Therefore, it is possible to suppress a decrease in the retention of the predetermined rotational phase angle.

(One variation)
FIG. 11 shows a cross-sectional configuration of a variable valve timing (VVT) device according to a modification of the present embodiment.

  The present modification is different from the above embodiment in that two drain chambers 308 are provided at positions facing the housing 301. About another point, since it is the structure similar to embodiment, the same code | symbol is attached | subjected about the structural member similar to the structural member of this embodiment.

  As shown in FIG. 11, the VVT device 30A according to the present modification is different from the VVT device 30 according to the embodiment in the shape of the side surface of the rotor vane 302, in particular, the vane body 302b. Although the configuration of the advanced angle side oil passage 311 and the retarded angle side oil passage 312 is different, the operation thereof is equivalent to that of the VVT device 30 according to the embodiment. Here, the VVT device 30A shown in FIG. 11 shows a state in which the cam shaft (vane body 302b) is at the most advanced position.

  In this modification, since two drain chambers 308 for discharging unnecessary oil from one of the working chambers 307 and 309 are provided, the oil is quickly discharged, so that the control responsiveness is improved. To do.

  As in the above embodiment, the oil drain hole 320 of each drain chamber 308 is provided in the radially inner portion of the housing 301 so that an oil reservoir is generated in the radially outer portion of the housing 301. Accordingly, also in this modification, the vane bodies 302b that define the respective drain chambers 308 swing to the advance working chambers 307 adjacent to the drain chambers 308 with the vane bodies 302b interposed between the gaps of the seal members 324. Since air does not flow in, it is possible to suppress a decrease in retention of a predetermined rotational phase angle.

  In this modification, although the control responsiveness is improved, the number of working chambers 309 driven by oil is reduced, and the driving force for the camshaft is reduced. Accordingly, the set number of drain chambers may be appropriately selected in consideration of the presence or absence of auxiliary equipment of the engine 2 or the driving load of the auxiliary equipment.

  The variable valve timing device for an engine according to the present invention can be applied to an application or the like that needs to suppress a decrease in control rotation phase retention due to a swinging motion of a rotor vane when a camshaft drive load varies.

2 Engine 6 High-pressure fuel pump 9 Crankshaft 18 Camshaft (intake side)
18a Cam part 19 Cam shaft (exhaust side)
19a Cam part 205 Bolt 30, 30A Variable valve timing device 301 Housing 302 Rotor vane 303 Sprocket 307 Advance working chamber 308 Drain chamber 309 Delay working chamber 311 Advance oil passage 312 Delay oil passage 324 Seal member 331 Lock pin V _{0, V 1} oil sump

Claims (5)

Control hydraulic pressure is supplied to either the advance working chamber or retard working chamber composed of a housing driven by the crankshaft of the engine and a rotor vane fixed to the camshaft to control the rotational phase of the camshaft A variable valve timing device for the engine,
A drain chamber is formed on the opposite side of either the advance working chamber or the retard working chamber with the rotor vane interposed therebetween,
In the drain chamber, an oil drain hole communicating with the outside is provided in the radially inner portion so that an oil reservoir is generated in the radially outer portion of the housing when the engine is operated. A variable valve timing device for engine. The variable valve timing apparatus for an engine according to claim 1,
A seal member is provided on a sliding surface that slides with the housing in the rotor vane,
The variable valve timing device for an engine according to claim 1, wherein the oil reservoir stores at least oil corresponding to a height in a radial direction of the housing in the seal member. The variable valve timing apparatus for an engine according to claim 1 or 2,
A variable valve timing apparatus for an engine, wherein the housing and the rotor vane form a drain chamber, a plurality of advance working chambers, and a plurality of retard working chambers. The variable valve timing apparatus for an engine according to any one of claims 1 to 3,
A variable valve timing apparatus for an engine, further comprising an auxiliary machine driven by a cam portion of the cam shaft. The variable valve timing apparatus for an engine according to claim 4,
The engine comprises a turbocharger;
The variable valve timing apparatus for an engine, wherein the auxiliary machine is a high-pressure fuel pump of a fuel supply system that injects fuel into a combustion chamber of the engine.

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