JP5783308B2 - Camshaft support structure - Google Patents

Description

  The present invention relates to a camshaft support structure in which a camshaft connected to a VVT (variable valve timing device) is supported by a rolling bearing.

  In recent years, an increasing number of automobile engines equipped with variable valve timing devices that control the valve timing of intake valves and exhaust valves according to the operating state of the engine for the purpose of high output, low fuel consumption and low exhaust gas. ing. Conventionally, in this type of variable valve timing device, a camshaft that drives an intake valve and an exhaust valve is supported by a slide bearing formed in a housing (see, for example, Patent Document 1). In this variable valve timing device, oil is supplied to the advance angle chamber and the retard angle chamber of the hydraulic equipment (VVT assembly) through the oil passage in the housing and the communication passage in the camshaft. Then, by supplying oil to the advance chamber and the retard chamber, the rotational phase of the camshaft relative to the crankshaft changes, and the valve timing is adjusted.

JP 2007-327362 A

  In the variable valve timing apparatus, the advance side and the retard side oil passages are formed side by side in the housing. The advance side and retard side oil passages in the housing communicate with the advance side and retard side communication passages in the camshaft via two annular grooves formed on the outer peripheral surface of the camshaft. ing. Adjacent annular grooves communicate with each other via a gap between the outer peripheral surface of the camshaft and the bearing surface. As a result, the oil flows between the two annular grooves and the operation responsiveness of the hydraulic equipment becomes dull. Therefore, it is desired to arrange the two annular grooves with a sufficient space in the direction of the rotation axis.

  By the way, in the structure which supports a camshaft with a sliding bearing, since friction is large and rotation resistance cannot fully be lowered | hung, the structure which supports a camshaft with a rolling bearing is proposed. However, in the structure in which the camshaft is supported by the rolling bearing, the width dimension in the rotation axis direction of the support portion (journal portion) of the housing and the camshaft is increased by the width of the bearing, and the engine is enlarged. In this case, if adjacent annular grooves are brought close to each other in order to reduce the width of the entire support portion, the oil circulates between the oil passages (annular grooves) on the advance side and the retard side, and the operation responsiveness of the hydraulic equipment is reduced. There was a problem of getting worse.

  The present invention has been made in view of the above points, and even if the camshaft is supported by a rolling bearing, the camshaft can improve the operation responsiveness of hydraulic equipment while reducing the size of the engine. It is an object to provide a support structure.

The support structure of the camshaft of the present invention, in the support structure of the camshaft to be supported by a rolling bearing provided with a cam shaft supporting the sprocket at one end to the housing, the housing is positioned a pre-Symbol camshaft in the axial direction And a plurality of oil passages having one end opened on a support surface that supports the camshaft, and the camshaft has a flange portion inserted into the thrust restriction groove on an outer peripheral surface thereof. A plurality of annular grooves arranged in parallel on the outer peripheral surface so as to communicate with the plurality of oil passages, and a communication path communicating the annular groove and a hydraulic chamber of a hydraulic device connected to the camshaft. is, the rolling bearing, so that to suppress the flow of oil between the annular groove adjacent said to partition between the annular groove adjacent Kamushi Are arranged to be pressed into the outer circumferential surface of the shift, and wherein arranged are possible between the outer peripheral surface of the cam shaft and the support surface of the housing.

Another camshaft support structure of the present invention is a camshaft support structure in which a camshaft supporting a sprocket at one end is supported by a rolling bearing provided in the housing, wherein the camshaft is axially disposed in the housing. And a plurality of oil passages having one end opened on a support surface that supports the camshaft, and a flange that is inserted into the thrust restriction groove on an outer peripheral surface of the camshaft. And an annular groove disposed on the outer peripheral surface so as to communicate with the oil passage, and a communication passage that communicates the annular groove and a hydraulic chamber of a hydraulic device connected to the camshaft. The bearing is axially external to the annular groove so as to prevent oil from flowing from the annular groove to the outside of the housing. Disposed Ri are arranged so as to partition the housing inside and outside, characterized in that it is press-fitted to the outer peripheral surface of the cam shaft.

  According to the present invention, even when the camshaft is supported by the rolling bearing, the operation responsiveness of the hydraulic device can be improved while reducing the size of the engine.

1 is a schematic configuration diagram of a variable valve timing system according to a first embodiment. It is a front view of the valve timing device concerning a 1st embodiment. It is sectional drawing of the peripheral part of the support structure of the camshaft which concerns on 1st Embodiment. It is sectional drawing of the peripheral part of the support structure of the camshaft which concerns on a comparative example. It is sectional drawing of the peripheral part of the support structure of the camshaft which concerns on 2nd Embodiment. It is sectional drawing of the peripheral part of the support structure of the camshaft which concerns on a modification.

  Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. In the following, an example in which the camshaft support structure of the present invention is applied to a variable valve timing device (VVT) of a four-wheeled vehicle will be described, but the present invention is not limited to this and can be changed as appropriate. For example, the camshaft support structure of the present invention can be applied to engines such as motorcycles and ships. Moreover, in the following description, in the comparative example, the second embodiment, and the modified example, the parts having the same names in the first embodiment will be described with the same reference numerals.

  With reference to FIG.1 and FIG.2, schematic structure of the variable valve timing apparatus which concerns on 1st Embodiment is demonstrated. FIG. 1 is a schematic configuration diagram of a variable valve timing system according to the first embodiment. FIG. 2 is a front view of the valve timing apparatus according to the first embodiment. In the following description, the variable valve timing system on the intake side will be described, but the variable valve timing system on the exhaust side has the same configuration. A variable valve timing system may be provided only on the intake side or the exhaust side.

  As shown in FIGS. 1 and 2, the variable valve timing system varies the valve timing by changing the rotational phase of the camshaft 1 with respect to a crankshaft (not shown), and is a hydraulic variable valve timing device 2 ( Hydraulic equipment). Power from the crankshaft is transmitted to the camshaft 1 through a variable valve timing device 2 by a timing chain (not shown). The variable valve timing device 2 is provided at one end of the camshaft 1 and is configured to transmit power to the camshaft 1 via oil supplied to the inside.

  The case 21 of the variable valve timing device 2 is fastened and fixed with a bolt 23 to a sprocket 22 over which a timing chain is stretched, and rotates integrally with the sprocket 22. The sprocket 22 is rotatably supported at one end of the camshaft 1 together with the case 21. A rotor 24 with a vane 241 is fastened and fixed to one end of the camshaft 1 with bolts 25, and the rotor 24 is accommodated inside the case 21 so as to be relatively rotatable. Inside the case 21, a plurality of hydraulic chambers are formed by a plurality of partition walls 211, and each vane 241 of the rotor 24 is accommodated in each hydraulic chamber. Each hydraulic chamber is partitioned into an advance chamber S1 and a retard chamber S2 by vanes 241 respectively.

  The advance chamber S1 and the retard chamber S2 communicate with an oil passage formed in the camshaft 1 and the housing 7 (see FIG. 3). When the volume of the advance chamber S1 is increased by the hydraulic pressure, the rotor 24 is rotated relatively to the advance side with respect to the case 21. Thereby, the camshaft 1 fixed to the rotor 24 rotates, and the valve timing changes to the advance side. On the other hand, when the volume of the retard chamber S2 is increased by the hydraulic pressure, the rotor 24 is rotated relatively to the retard side with respect to the case 21. Thereby, the camshaft 1 fixed to the rotor 24 rotates, and the valve timing changes to the retard side. The details of the oil passages of the camshaft 1 and the housing 7 will be described later.

  The vane 241 is provided with a lock pin 26 that connects the rotor 24 to the case 21 until the hydraulic pressure reaches a certain level when the engine is started. The lock pin 26 is accommodated in a bottomed accommodation hole 242 formed in the vane 241 and is urged toward the front side of the case 21 by a spring 27 disposed on the bottom surface of the accommodation hole 242. A lock hole 212 is formed on the front surface of the case 21 corresponding to the lock pin 26, and the rotor 24 and the case 21 are integrated by the lock pin 26 entering the lock hole 212. Further, the lock pin 26 is configured to be returned into the accommodation hole 242 against the urging force of the spring 27 by the release hydraulic pressure.

  The variable valve timing device 2 is operated by hydraulic pressure from the oil control valve 3 (OCV). Oil is pumped from the oil pan 5 and supplied to the oil control valve 3 by an oil pump 4 driven by engine power. The oil control valve 3 is a so-called electromagnetic spool valve, and includes an advance port P1, a retard port P2, an input port P3, a discharge port P4, and the like. The advance port P1 and the retard port P2 are connected to the advance chamber S1 and the retard chamber S2 via the oil passages of the camshaft 1 and the housing 7, respectively. The input port P3 is connected to the oil pump 4 via the oil filter 6, and the discharge port P4 is connected to the oil pan 5. The oil control valve 3 switches the communication state between the ports by moving the spool 31 forward and backward to change the internal flow path.

  For example, when the advance port P1 communicates with the input port P3 and the retard port P2 communicates with the discharge port P4, the oil is supplied to the advance chamber S1 with the oil discharged from the retard chamber S2, and the valve timing Is changed to the advance side. Further, when the advance port P1 communicates with the discharge port P4 and the retard port P2 communicates with the input port P3, the oil is supplied to the retard chamber S2 in a state where the oil is discharged from the advance chamber S1, and the valve timing. Is changed to the retard side. Further, when the advance port P1 and the retard port P2 are disconnected from the input port P3 and the discharge port P4, the hydraulic pressure in the advance chamber S1 and the retard chamber S2 is maintained, and the valve timing is fixed.

  In the variable valve timing system configured as described above, the sprocket 22 and the camshaft 1 are connected by the lock pin 26 at the time of engine start when hydraulic pressure does not work. The variable valve timing system releases the lock when the hydraulic pressure reaches a certain level, and adjusts the valve timing by driving the oil control valve 3 according to the operating state such as the engine speed.

  Here, a camshaft support structure, which is a characteristic part of the variable valve device according to the present embodiment, will be described in comparison with a comparative example. FIG. 3 is a cross-sectional view of a peripheral portion of the camshaft support structure according to the first embodiment. FIG. 4 is a cross-sectional view of a peripheral portion of a camshaft support structure according to a comparative example.

  As shown in FIG. 3, the camshaft 1 according to the present embodiment is rotatably supported by the housing 7 via a rolling bearing 8. The housing 7 includes an upper housing 71 that supports the upper half of the camshaft 1 and a lower housing 72 that supports the lower half of the camshaft 1. A cylindrical support surface 75 is formed on the upper housing 71 and the lower housing 72. The camshaft 1 is inserted into a cylindrical support space formed by the support surface 75. In the lower housing 72, oil passages 724 and 725 on the advance side and the retard side are formed side by side in the rotation axis direction of the camshaft 1.

  The advance side oil passage 724 has one end opened to the support surface 75 and the other end connected to the advance port P 1 of the oil control valve 3. The retard side oil passage 725 has one end opened to the support surface 75 and the other end communicated with the retard port P 2 of the oil control valve 3. The support surface 75 is formed with an annular housing groove 76 for housing the rolling bearing 8 press-fitted into the camshaft 1. The housing groove 76 is located between the adjacent oil passages 724 and 725 in the lower housing 72, and causes the rolling bearing 8 to function as a partition wall between the oil passages 724 and 725. A semi-annular thrust restricting groove 717 for positioning the camshaft 1 in the axial direction is formed in the support surface 75 of the upper housing 71 at a position opposite to the sprocket 22 side with respect to the accommodating groove 76.

  A rotor 24 with a vane 241 is fixed to the end face 18 via a bolt 25 on the camshaft 1. The rotor 24 is positioned with respect to the camshaft 1 via a knock pin 28 press-fitted into the end face 18 of the camshaft 1. A sprocket 22 is rotatably supported near the end surface 18 of the camshaft 1. On the side of the camshaft 1, an advance chamber S1 and a retard chamber S2 are formed by the case 21 fixed to the sprocket 22 and the vane 241 of the rotor 24 (see FIG. 2). On the outer peripheral surface 11 of the camshaft 1, an advance side and a retard side annular groove 12, 13 are formed corresponding to the advance side and retard side oil passages 724, 725 of the lower housing 72.

  The advance-side annular groove 12 communicates with the advance chamber S1 through a communication passage 14 extending in the direction of the rotation axis in the camshaft 1. The retarded-side annular groove 13 communicates with the retarded chamber S2 through a communication passage 15 extending in the direction of the rotation axis in the camshaft 1. A rolling bearing 8 is press-fitted into the partition wall 16 between the adjacent annular grooves 12 and 13. The rolling bearing 8 is configured by arranging a plurality of rolling elements 83 between an outer ring 81 and an inner ring 82. A seal member 84 is provided between the outer ring 81 and the inner ring 82 at both ends in the rotation axis direction of the rolling bearing 8, and the inside of the rolling bearing 8 is liquid-tightly sealed by the seal member 84. Further, the outer peripheral surface 11 of the camshaft 1 is formed with a flange portion 17 to be inserted into the thrust restricting groove 717 of the upper housing 71.

  The camshaft 1 is supported by the housing 7 with a slight gap C <b> 1 between the outer peripheral surface 11 and the support surface 75. For this reason, when oil flows into the annular grooves 12 and 13 from the oil passages 724 and 725, part of the oil enters the gap C <b> 1 between the outer peripheral surface 11 and the support surface 75. At this time, the oil flow between the adjacent annular grooves 12 and 13 is blocked by the rolling bearing 8 with the seal member 84. In addition, the flow of oil that has entered the housing groove 76 is suppressed by a narrow gap C <b> 2 between the outer peripheral surface of the outer ring 81 and the bottom surface of the housing groove 76 that are designed in consideration of the thermal expansion of the rolling bearing 8. With such a configuration, the deterioration of the operation responsiveness of the variable valve timing device 2 due to the oil flow between the oil passages 724 and 725 on the advance side and the retard side is prevented.

  For the oil going out of the housing 7, the width L2 between the annular groove 12 on the advance side and the end face 73 on the sprocket 22 side of the housing 7, the annular groove 13 on the retard side and the sprocket 22 side of the housing 7 is By ensuring the sufficient width dimension L3 between the opposite end surface 74, an increase in the amount of leakage to the outside can be suppressed. Thereby, deterioration of the operation responsiveness of the variable valve timing apparatus 2 due to an increase in oil leakage to the outside of the housing 7 is prevented.

  Further, since the width dimension L1 of the partition wall 16 between the annular grooves 12 and 13 and the width dimension L4 of the rolling bearing 8 are formed to be substantially the same width, and the rolling bearing 8 is installed in the partition wall 16, the housing 7 and the support portion (journal portion) of the camshaft 1 need not be extended to newly provide an installation portion for the rolling bearing 8. Therefore, it is not necessary to increase the width L5 in the rotation axis direction of the support portion for the rolling bearing 8, and the engine can be downsized. As described above, in this embodiment, even when the camshaft 1 is supported by the rolling bearing 8, it is possible to improve the operation responsiveness of the variable valve timing device 2 while reducing the size of the engine. is there.

  As shown in FIG. 4, in the camshaft support structure according to the comparative example, the installation position of the rolling bearing 8 is different from the camshaft support structure according to the present embodiment. The rolling bearing 8 according to the comparative example is disposed in a housing groove 76 formed on the sprocket 22 side of the housing 7, and the adjacent annular grooves 12 and 13 are cams sandwiching a partition wall portion having a predetermined width dimension L1. It is formed on the outer peripheral surface 11 of the shaft 1.

  In the camshaft support structure according to this comparative example, adjacent annular grooves 12 and 13 are formed with a partition wall having a predetermined width dimension L1 interposed therebetween, but the support surface 75 of the housing 7 and the outer periphery of the camshaft 1 are formed. The surface 11 communicates with the gap C1. Therefore, the flow of oil between the advance-side and retard-side annular grooves 12 and 13 cannot be sufficiently suppressed, and the operation responsiveness of the variable valve timing device 2 becomes dull. Further, an installation portion for the rolling bearing 8 is newly provided in the support portion of the housing 7 and the camshaft 1 with a width L4 in order to arrange the rolling bearing 8. Therefore, the width dimension L5 in the rotation axis direction of the support portion of the housing 7 and the camshaft 1 increases, and the engine cannot be downsized.

  As described above, the camshaft support structure according to the first embodiment has an operational responsiveness of the variable valve timing device 2 while downsizing the engine as compared with the camshaft support structure according to the comparative example. Can be improved. In the present embodiment, the seal member 84 that closes the space between the outer ring 81 and the inner ring 82 is provided at both ends of the rolling bearing 8 in the rotation axis direction. As long as the oil flow between the grooves 12 and 13 can be suppressed, the seal member 84 may not be provided.

  As described above, according to the support structure for the camshaft 1 according to the present embodiment, the oil flow between the adjacent annular grooves 12 and 13 is suppressed by the rolling bearing 8, and the rotational resistance of the camshaft 1 is reduced. The operation responsiveness of the variable valve timing device 2 can be improved. Further, since the rolling bearing 8 is disposed between the annular grooves 12 and 13, there is no increase in the width L5 of the support portion due to the rolling bearing 8, and the engine can be downsized.

  In addition, this invention is not limited to the said embodiment, It can change and implement variously. In the above-described embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited to this, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  For example, in the first embodiment, the width dimension L1 of the partition wall portion 16 between the adjacent annular grooves 12 and 13 and the width dimension L4 of the rolling bearing 8 are formed to be substantially the same width, but this configuration is limited. It is not something. As shown in the second embodiment in FIG. 5, the width dimension L <b> 1 of the partition wall 16 may be smaller than the width dimension L <b> 4 of the rolling bearing 8. Even in this configuration, since the adjacent annular grooves 12 and 13 are partitioned by the rolling bearing 8, the oil flow between the annular grooves 12 and 13 can be suppressed.

  In the second embodiment, since the mutual oil flow can be suppressed even if the interval between the annular grooves 12 and 13 is narrowed, the support portions of the housing 7 and the camshaft 1 are compared with those of the first embodiment. The width dimension L5 in the rotation axis direction can be further narrowed. In this case, annular grooves 77 and 78 may be formed on the support surfaces 75 of the upper housing 71 and the lower housing 72 so as to face the annular grooves 12 and 13 of the camshaft 1.

  With this configuration, even if part of the outlets of the advance side and retard side oil passages 724 and 725 formed on the support surface 75 are blocked by the rolling bearing 8, the annular grooves that continue to the outlets of the oil passages 724 and 725 Oil can flow into the annular grooves 12 and 13 from the periphery of the camshaft 1 through 77 and 78. Therefore, a sufficient amount of oil can be secured to the advance chamber S1 and the retard chamber S2, and the operation responsiveness of the variable valve timing device 2 can be improved.

  In addition, as shown in the modification of FIG. 6, the rolling bearing 8 may be arranged in the accommodation groove 76 formed on the sprocket 22 side of the housing 7 so as to overlap with a part of the annular groove 12 on the advance side. According to this configuration, even if the portion near the sprocket 22 of the camshaft 1 is supported by the rolling bearing 8, the width L5 in the rotation axis direction of the support portion of the housing 7 and the camshaft 1 is set to the first dimension. It can be suppressed to the same extent as the embodiment. In addition, since a part of the outlet of the advance side oil passage 724 formed in the support surface 75 is blocked by the rolling bearing 8, the support surface 75 of the upper housing 71 and the lower housing 72 is provided in the second embodiment. An annular groove 77 is formed in the same manner as in FIG.

  In the modified example, the amount of oil flowing between the adjacent annular grooves 12 and 13 is substantially the same as that in the comparative example, but the oil from the annular groove 12 on the advance side to the outside of the housing 7 is attached to the seal member 84. Reduced by the rolling bearing 8. Therefore, the operation responsiveness to the advance side of the variable valve timing device 2 can be improved. Further, instead of the configuration in which the rolling bearing 8 is disposed so as to prevent the oil from flowing out of the housing 7 from the annular groove 12, the rolling is performed so as to suppress the oil from flowing out of the housing 7 from the annular groove 13. A bearing 8 may be arranged.

  Further, in each of the above-described embodiments, the seal member that closes the space between the inner ring and the outer ring is provided at both ends in the rotation axis direction of the rolling bearing, but the present invention is not limited to this configuration. The sealing member should just be provided in either one of the both ends of the rotating shaft direction of a rolling bearing. Further, the seal member is not limited to a configuration disposed between the inner ring and the outer ring, and may be configured to be affixed to end faces of the inner ring and the outer ring.

  In each of the above embodiments, one oil passage, an annular groove, and a communication passage are provided on the advance side and the retard side, respectively. However, the present invention is not limited to this configuration. A plurality of oil passages, annular grooves, and communication passages may be provided on the advance side and the retard side, respectively.

DESCRIPTION OF SYMBOLS 1 Camshaft 11 Outer peripheral surface 12, 13 Annular groove 14, 15 Communication path 2 Variable valve timing device 7 Housing 71 Upper housing 72 Lower housing 724, 725 Oil path 75 Support surface 76 Housing groove 77, 78 Annular groove 8 Rolling bearing 81 Outer ring 82 Inner ring 84 Seal member S1 Advance chamber S2 Delay chamber

Claims (2)

In a camshaft support structure in which a camshaft supporting a sprocket at one end is supported by a rolling bearing provided in a housing,
It said housing includes a thrust regulating groove for positioning the pre-Symbol camshaft axially, a plurality of oil passages having an open end on the supporting surface for supporting the cam shaft is provided,
The camshaft has a flange portion inserted into the thrust regulating groove on an outer peripheral surface thereof, a plurality of annular grooves arranged in parallel on the outer peripheral surface so as to communicate with the plurality of oil passages, and the annular groove And a communication path that connects the hydraulic chamber of the hydraulic device connected to the camshaft,
The rolling bearing is press-fitted and arranged on the outer peripheral surface of the camshaft so as to partition the adjacent annular grooves so as to suppress the oil flow between the adjacent annular grooves , and the support surface of the housing. A camshaft support structure, wherein the camshaft support structure is disposed between the camshaft and an outer peripheral surface of the camshaft. In a camshaft support structure in which a camshaft supporting a sprocket at one end is supported by a rolling bearing provided in a housing,
The housing is provided with a thrust restricting groove for positioning the camshaft in the axial direction, and a plurality of oil passages having one end opened on a support surface that supports the camshaft,
The cam shaft has a flange portion inserted into the thrust restricting groove on an outer peripheral surface thereof, an annular groove disposed on the outer peripheral surface so as to communicate with the oil passage, and connected to the annular groove and the cam shaft. A communication passage communicating with the hydraulic chamber of the hydraulic equipment is formed,
The rolling bearing is disposed so as to partition the inside and outside of the housing in an axial direction with respect to the annular groove so as to prevent oil from flowing from the annular groove to the outside of the housing. A camshaft support structure, wherein the camshaft is press-fitted into an outer peripheral surface of the camshaft.

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