JP2849915B2 - Transmission band tension adjusting device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention (1) Industrial application field The present invention relates to an engine body in which a crankshaft, a valve operating camshaft, and a balancer shaft are rotatably supported with their axes parallel.
Endless first for power transmission between crankshaft and valve cam shaft
The present invention relates to a transmission band tension adjusting device for an internal combustion engine in which a first tensioner slidingly contacting a transmission band and a second tensioner slidingly contacting an endless second power transmission band between a crankshaft and a balancer shaft are supported.

(2) Prior Art Conventionally, a pair of tensioners for adjusting the tensions of two endless transmission belts are arranged coaxially, whereby the arrangement of the tensioners is made compact. It is known from Japanese Patent Publication No.

(3) Problems to be Solved by the Invention However, in the case where a pair of tensioners are coaxially arranged as described above, a large load is applied to a common support shaft that supports the tensioners. If the tensioner for adjusting the transmission band tension, which has a higher tension, is supported on the distal end side of the support shaft, the load applied to the base support portion of the support shaft increases.

By the way, the belt tension for driving the valve operating camshaft is a reaction force from the cam side in addition to the frictional force in the bearing portion of the camshaft, so that the belt tension for driving the balancer shaft is increased. Greater than.

The present invention has been made in view of such circumstances,
It is an object of the present invention to provide a transmission band tension adjusting device for an internal combustion engine that enables a compact arrangement by supporting two tensioners on a common support shaft and that can reduce a load applied to the support shaft.

B. Configuration of the Invention (1) Means for Solving the Problems In order to achieve the above object, according to the feature of the invention of claim 1, a support shaft parallel to the crankshaft has its base end screwed to the engine body. The first and second tensioners are commonly supported on the support shaft by disposing a first tensioner on the base end side of the support shaft. The first and second tensioners are
The first and second outer races slidingly contacting the first and second transmission belts, the first and second inner races through which the support shaft is inserted, and the plurality of rolling elements respectively provided between the outer races and the inner races. A lock nut abutting on an axially outer end surface of the second inner race is screwed to a tip end of a spindle protruding from the second tensioner, and a first screw provided at a base end of the spindle to be screwed to the engine body. The diameter of the portion is set to be larger than the diameter of the second screw portion provided at the tip of the spindle for screwing the lock nut, and according to the feature of the invention of claim 2, the feature of the invention of claim 1 In addition to the above, a flange portion protruding radially outward to abut on the engine body is provided at a portion near the base end of the support shaft.
In addition to the above features of the second aspect, a screw hole provided in the engine main body for screwing a base end of the support shaft is communicated with a water jacket provided in the engine main body, and the support shaft connects the seal member to the engine main body. And screwed into the screw hole.

According to the fourth aspect of the present invention, a support shaft parallel to the crankshaft has a base end screwed into the engine main body and protrudes from the engine main body. The support shaft has a first tensioner connected to the base end of the support shaft. The first and second tensioners are disposed on the same side and supported in common. The first and second tensioners have first and second outer races slidingly contacting the first and second transmission bands, respectively, and the support shaft is inserted therethrough. A first and second inner races, and a plurality of rolling elements respectively interposed between the outer races and the inner races, and a lock nut abutting on an axially outer end face of the second inner race protrudes from the second tensioner. At least the operation part of the lock nut is attached to the engine main body and screwed to the tip of the support shaft.
According to the invention of claim 5, the support shaft parallel to the crankshaft has its base end screwed to the engine main body and protrudes from the engine main body. The first and second tensioners are commonly supported on the support shaft by disposing a first tensioner on the base end side of the support shaft. The first and second tensioners slide on the first and second transmission bands, respectively. The first and second outer races are in contact with each other, the first and second inner races through which the support shaft is inserted, and a plurality of rolling elements interposed between the respective outer races and the respective inner races. A lock nut abutting on an end face is screwed to a tip end of a spindle protruding from the second tensioner, and is attached to the engine body to cover the first and second transmission bands. Openings for maintenance Is, maintenance cover covering the maintenance opening is detachably attached to the support shaft distal end by a screw member.

(2) Operation According to the present invention, since the first and second tensioners are supported by the common support shaft, the arrangement of the tensioner can be made compact, and the support from the second tensioner at the support shaft tip side to the support shaft. Since the load is smaller than the load applied to the support shaft from the first tensioner on the support shaft base end side, the load on the support shaft distal end side is reduced accordingly.

According to the first aspect of the present invention, the first thread portion at the base end of the spindle screwed to the engine body has a larger diameter than the second thread portion at the tip of the spindle for screwing the lock nut. When the lock nut is loosened, the small diameter second thread is easier to loosen,
The first screw portion is not easily loosened.

According to the second aspect of the present invention, the support shaft for guiding the first and second tensioners is screwed to the engine body such that the flange provided near the base end of the support shaft comes into contact with the outer surface of the side wall. Once the support shaft is mounted, there is no inclination of the axis, so the lock nut is loosened and the first
When the lock nut is tightened again after the adjustment of the second tensioner and the first tensioner, the first and second tensioners do not tilt.

According to the third aspect of the present invention, since the screw hole provided on the engine body side for screwing the support shaft communicates with the water jacket, the support shaft is cooled by the water in the water jacket, and the first shaft is cooled. And the second tensioner is also cooled efficiently.
Further, even if the screw hole communicates with the water jacket, water leakage from the screw hole is suppressed by the seal member between the spindle and the engine body.

According to the fourth aspect of the present invention, since the lock nut can be operated from the outside of the side cover, the tension can be easily adjusted by the first and second tensioners.

According to the fifth aspect of the present invention, if the maintenance cover is removed without removing the entire side cover, the two tensioners can be visually checked, and the maintenance cover is mounted on a rigid support shaft. The support rigidity for the maintenance cover is increased, and the closed state is reliably maintained.

(3) Embodiment Hereinafter, an embodiment in which the present invention is applied to a DOHC type in-line four-cylinder internal combustion engine will be described with reference to the drawings.

First, the first embodiment of the present invention will be described with reference to FIGS.
An embodiment will be described. In FIGS. 1, 2, 3, and 4, an engine body E is configured by connecting a cylinder head 2 to an upper portion of a cylinder block 1 and a lower portion of the cylinder block 1. An oil pan 3 is connected to the head, and a head cover 4 is connected to the upper part of the cylinder head 2.

The cylinder block 1 has an upper cylinder barrel portion 1a.
And a lower half crankcase portion 1b made of an aluminum alloy. The cylinder barrel portion 1a is provided with four cylinder bores 5 arranged in series, and a piston 6 is slidably fitted in each of the cylinder bores 5. A plurality of journal bearings 7 are spaced from each other along the direction in which the cylinder bores 5 are arranged in the crankcase portion 1b, and a bearing cap 8 fixed to the lower surface of each journal bearing 7 is provided. A crank shaft 9 is rotatably supported by the journal bearings 7. The crank pins 9 a of the crank shaft 9 are connected to the pistons 6 via connecting rods 10. The bearing caps 8 are integrally connected by a bridge member 11.

At one axial end of the crankshaft 9, the cylinder block 1
An oil pump 12 driven by the crankshaft 9 is disposed on the outer surface 1c of the side wall of the vehicle. The oil pump 12 includes a pump case 13 attached to the outer surface 1c of the side wall of the cylinder block 1 and a rotor 14 fixed to the crankshaft 9 housed therein. Is connected to an oil strainer 17 via a suction pipe 16. A discharge port 19 provided in the pump case 13
Is connected to a lubricating oil passage 19 formed in the cylinder block 1 in parallel with the crankshaft 9. The other axial end of the crankshaft 9 slightly projects from the other end side wall of the cylinder block 1, and a transmission is connected to the other end of the crankshaft 9 via a clutch (not shown).

5 and 6, the crankshaft 9
A pair of balancer shafts 21 and 22 are disposed at a position substantially symmetric with respect to a vertical plane passing through the axis of the crankshaft 9 so as to be rotatable in parallel with the crankshaft 9. These balancer shafts 21 and 22 are for suppressing secondary vibration of the engine,
The one end in the axial direction is inserted through the cylinder block 1 while protruding from the side wall outer surface 1c of the cylinder block 1. Thus, both balancer shafts 21 and 22 have eccentric weight portions 21a and 21b; 22a and 22b spaced apart from each other near their other ends in the axial direction. A pair of bearing holes for supporting the portion of the balancer shaft 21 near the other end in the axial direction.
23 and 24 are provided, and a pair of bearing holes 25 and 26 for supporting a portion near the other axial end of the other balancer shaft 22 and a bearing hole 27 for supporting a portion near one axial end of the balancer shaft 22 are provided. Can be

One end of the crankshaft 9 is a pump case of the oil pump 12
The first drive pulley 28 of the first winding transmission system T1 is fixed to the protruding end of the crankshaft 9 and is closer to the cylinder block 1 than to the first drive pulley 28. The second drive pulley 29 of the second winding transmission system T2 is fixed to the side going away. Thus, those drive pulleys 28, 29
Is driven to rotate in the direction indicated by the arrow in FIG.

The first winding transmission system T1 includes an intake-side valve operating cam mechanism 30 that is rotatably supported by the cylinder head 2 in parallel with the crankshaft 9 to drive the intake-side valve operating mechanism, and an exhaust-side valve operating mechanism. An exhaust valve camshaft 31 that is rotatably supported by the cylinder head 2 in parallel with the crankshaft 9 to be driven, and a water pump that is mounted on the outer surface 1c of the side wall of the cylinder block 1
32, a first drive pulley 28, driven pulleys 33 and 34 for driving camshafts respectively fixed to both camshafts 30 and 31, and a pump shaft 3 of the water pump 32.
A driven pulley 35 for driving a water pump fixed to 2a,
And a first timing belt 36 as an endless first transmission band suspended around each of the pulleys 28, 33, 34, 35.

Further, the second winding transmission system T2 is a transmission system for driving the pair of balancer shafts 21 and 22, and is disposed on a side farther from the cylinder block 1 than the first winding transmission system T1.
Thus, the second winding transmission system T2 includes a second drive pulley 29,
The driven pulley 37 for reverse rotation which is linked and connected to one balancer shaft 21, the driven pulley 38 for normal rotation drive of the other balancer shaft 22, and the endless second driven pulley 38 which is suspended around each pulley 29, 37, 38. And a second timing belt 39 as a transmission band.

7 and 8, the balancer shaft 21
A gear case 42 that covers a part of the pump case 13 is attached to the pump case 13 at a portion corresponding to. That is, the gear case 42 is attached to the cylinder block 1 together with the pump case 13 by the bolt 43. The driven pulley 37 for reverse rotation is provided with a gear case 42 of a rotary shaft 44 rotatably supported by the gear case 42 in parallel with the balancer shaft 21.
Fixed to the protruding end from Moreover, one end of the balancer shaft 21 protrudes into the gear case 42 while being rotatably supported by the pump case 13, and a gear 41 fixed to the end of the balancer shaft 21 between the pump case 13 and the gear case 42.
And the gear 40 integrally provided at the inner end of the rotary shaft 44 are meshed with each other. Therefore, the balancer shaft 21 receives the power from the reverse driven driven pulley 37 and the gear meshing with each other.
It is transmitted via 40,41. That is, both balancer shafts 21 and 22
Are driven to rotate in opposite directions.

9, a screw hole 95 communicating with a water jacket 94 provided in the cylinder block 1 is formed on the outer surface 1c of the side wall of the cylinder block 1 above the crankshaft 9 so as to be parallel to the crankshaft 9. The support shaft 45 is screwed into the screw hole 95. That is, the support shaft 45 is configured such that the proximal first screw portion 45a and the shaft portion 45b that are screwed into the screw holes 95 are coaxially connected via the flange portion 45d that protrudes outward in the radial direction. And the first end of the shaft 45b.
A second screw portion 45c having a smaller diameter than the screw portion 45a is provided.

The support shaft 45 is implanted in the cylinder block 1 by screwing the first screw portion 45a into the screw hole 95 so that the flange portion 45d contacts the side wall outer surface 1c. Moreover, a water jacket 94 is provided between the side wall outer surface 1c and the flange portion 45d.
An annular seal member 96 is interposed in order to prevent water leakage.

A first tensioner 46 for adjusting the tension of the first timing belt 36 in the first winding transmission system T1 is fitted and inserted into the support shaft 45 implanted in the cylinder block 1.
A second tensioner 47 for adjusting the tension of the second timing belt 39 in the second winding transmission system T2 is inserted.

10 and 11, the first tensioner 46 is
A plurality of first balls 50 as a plurality of first rolling elements are interposed between a first inner ring 48 and a first outer ring 49 pressed against the outer surface of the first timing belt 36. It is swingably supported by the cylinder block 1 via the bracket 51.

The first inner ring 48 is formed in a cylindrical shape with a bottom opened to the cylinder block 1 side, and a washer 97 is interposed between the inner end surface of the first inner ring 48, that is, the open end side end surface, and the cylinder block 1. Is done. In addition, the axially outer end face of the first inner ring 48 is disposed more inward than the axially outer end face of the first outer ring 49. The washer 97 is made of a material having a higher buckling strength than a material forming the cylinder block 1, for example, an aluminum alloy, for example, an iron-based material.

The first bracket 51 is a short cylindrical main body 51a that is press-fitted and fixed to the outer surface of the base end of the first inner ring 48, and protrudes radially outward from an end of the main body 51a on the cylinder block 1 side. The main body 51a has a protrusion 51b and an arm 51c extending outward from an end of the main body 51a on the cylinder block 1 side at a position substantially symmetrical to the protrusion 51b. The main body 51a is press-fitted and fixed to the first inner ring 48 such that a part of the main body 51a is housed and disposed in the first outer ring 49 of the first tensioner 46. Also protrusion 51
a is provided with a support hole 52, and the cylinder block 1
The first bracket 51, that is, the first tensioner 46 is swingably supported by the cylinder block 1 by inserting the support pin 53 implanted in the support hole 52 into the support hole 52.

An arc-shaped long hole 54 centering on the support pin 53 is formed at an axially outer end portion, that is, a closed end portion of the first inner ring 48, and the shaft portion of the support shaft 45 is formed in the long hole 54. 45b is inserted. The other end of the first tension spring 55 whose one end is engaged with the cylinder block 1 is engaged with the arm portion 51c, and the first tension spring 46 is actuated by the spring force of the first tension spring 55.
The first outer ring 49 is pressed against the first timing belt 36 from outside thereof, whereby a constant tension is applied to the first timing belt 36.

At the end of the arm portion 51c of the first bracket 51, a temporary fastening long hole 98 is provided along an arc centered on the support pin 53. On the other hand, a screw shaft 99 projecting outward through the temporary fastening long hole 98 is implanted on the side wall outer surface 1c of the cylinder block 1, and the temporary fastening nut 100 is screwed onto the screw shaft 99. Then, the swinging position of the first bracket 51, that is, the first tensioner 46, can be temporarily fixed.

The second tensioner 47 includes a plurality of second balls 57 as second rolling elements interposed between a second inner ring 56 and a second outer ring 58 pressed against the second timing belt 39. 2nd inner ring
56 is formed in a cylindrical shape with a bottom opening to the cylinder block 1 side, and the inner end face in the axial direction of the second inner ring 56, that is, the open end face is inserted and arranged in the first outer ring 49 of the first tensioner 46. And abuts against the axially outer end face of the first inner ring 48, whereby the first and second tensioners 46 and 47
Are arranged so as to allow relative sliding in a plane orthogonal to the axis of the support shaft 45.

A second bracket 59 supported on the cylinder block 1 so as to be swingable about an axis parallel to the crankshaft 9 is fixed to the second inner ring 56 of the second tensioner 47.
The second bracket 59 is bent and formed so that one end thereof is disposed close to the outer surface 1c of the side wall of the cylinder block 1 while being supported by the cylinder block 1 at an intermediate portion in the longitudinal direction, while avoiding the first and second timing belts 36 and 39. The outer end of the second inner ring 56 of the second tensioner 47 is press-fitted and fixed to the other end of the second bracket 59.

To support the second bracket 59 so as to be able to swing, a cylindrical support protrusion 101 is provided on the outer surface 1c of the side wall of the cylinder block 1, and an intermediate part of the second bracket 59 is
1 is in contact with the front end via a sliding plate 102. In addition, the second bracket 59 is swingably supported by the bolt 60 that passes through the second bracket 59 and the sliding plate 102 and is screwed to the support projection 101.

An arc-shaped long hole 61 centering on the bolt 60 is formed in the center of the second inner ring 56, and the shaft portion 45 b of the support shaft 45 is inserted into the long hole 61. Furthermore, a second tension spring 62 is provided between the other end of the second bracket 59 and the cylinder block 1.
The second outer ring 58 is pressed against the second timing belt 39 from the outside thereof by the spring force of the second tension spring 62, whereby a constant tension is applied to the second timing belt 39. In the second tensioner 7, the width of the second outer ring 58 is equal to the width of the first outer ring 49 in the first tensioner 46.
Is set to be smaller than the width.

In FIG. 9A, the outer diameter D1 of the first inner ring 48 is set to be larger than the outer diameter D2 of the second inner ring 56 (D1> D2). The ratio of the outer diameter D4 of the second outer ring 58 to the outer diameter D2 of the second inner ring 56 (D4 / D
2) is the outer diameter D of the first outer ring 49 with respect to the outer diameter D1 of the first inner ring 48
3 (D3 / D1) (D4 / D2> D3 / D1). Based on such a relationship, for example, the first
The outer diameter D3 of the outer ring 49 is smaller than the outer diameter D4 of the second outer ring 58 (D3
<D4) The virtual circle diameter on which the first ball 50 is set and set
D5 is set to be larger than the virtual circle diameter D6 where the second ball 57 is arranged (D5> D6).

In this manner, the first timing belt 36 in the first winding transmission system T1 moves the slack side between the first drive pulley 28 and the driven pulley 35 for driving the water pump to the first tensioner 46.
When the gear case 42 is pressed inward from the outside to the inside, the gear case 42 is deeply bent inward, and the gear case 42 is disposed in an empty space generated by the bending. Moreover, the pressing direction of the first timing belt 36 by the first tensioner 46,
The angle α between the direction in which the second tensioner 47 presses the second timing belt 39 is set to 90 degrees or more, preferably 120 degrees or more.

The first winding transmission system T1 and the second winding transmission system T2 are covered by a side cover 65, and the tip of the support shaft 45 projects outward through the side cover 65 and locks. The nut 66 also protrudes outward from the side cover 65 to enable operation from outside. That is, the second tensioner 47 is screwed into the second threaded portion 45c at the tip of the support shaft 45.
Lock nut 66 abutting on the outer end surface of the second inner ring 56 at
However, the operation portion is rotatably engaged with the side cover 65 so as to arrange the operation portion outside the side cover 65, so that the lock nut 66 can be rotated from the outside of the side cover 65. By tightening the lock nut 66, the inner rings 48, 56 of the first and second tensioners 46, 47 are relatively movable in a plane orthogonal to the axis of the support shaft 45 and are brought into contact with each other.

A rotating wheel 67 protruding outward from the side cover 65 is fixed to the crankshaft 9, and a third driving pulley 68 of a third winding transmission system T <b> 3 is attached to the rotating wheel 67 on the inner side in the axial direction. And the fourth drive pulley 69 of the fourth winding transmission system T4 is integrally provided on the outer side in the axial direction.

The third winding transmission system T3 is a transmission system for driving the AC generator 70 and the air conditioner compressor 71 attached to the cylinder block 1, and includes a third drive pulley 68.
And a driven pulley 72 for driving the AC generator fixed to the input shaft of the AC generator 70, a driven pulley 73 for driving the compressor fixed to the input shaft of the compressor 71 for the air conditioner, and each pulley 68, 72, 73. Endless endless belt 74
It is composed of The fourth winding transmission system T4 is a transmission system for driving a power steering hydraulic pump 75 mounted on the cylinder head 2, and includes a fourth drive pulley 69.
And a driven pulley 76 for driving the hydraulic pump, which is fixed to the input shaft of the hydraulic pump 75, and an endless belt 77 suspended by the two pulleys 69, 76.

Next, the structure of the lubricating oil supply system will be described. The lubricating oil supplied from the oil pump 12 to the lubricating oil passage 19 provided in the cylinder block 1 is provided between the two inner cylinder bores 5 along the arrangement direction. The portion corresponding to the located journal bearing 7 is guided to an oil filter 80 attached to the side surface of the cylinder block 1. Moreover, cylinder block 1
An oil passage 81 for guiding the lubricating oil from the oil filter 80 to the valve operating mechanism above and an oil passage 82 for guiding the lubricating oil downward are formed.

On the other hand, a bridge member 11 for interconnecting the bearing caps 8 is provided with a central oil passage 83 corresponding to the crankshaft 9 and side portions corresponding to the balancer shafts 21 and 22 on both sides of the central oil passage 83, respectively. Oil passages 84 and 85 are formed in parallel with the crankshaft 9. The bridge member 11 includes the oil passages 83, 84, 85
Are connected to each other at a longitudinally intermediate portion of the oil passages 83 to 85 so as to be orthogonal to the oil passages 83 to 85.

Each of the bridge member 11 and each of the bearing caps 8 is provided with an oil supply passage 87 extending upward with a lower end communicating with a central oil passage 83 so as to supply lubricating oil to a support portion of the crankshaft 9. In the portions corresponding to the bearing holes 23 and 24 of the balancer shaft 21, the lower end of the bridge member 11, the bearing cap 8 and the cylinder block 1 is communicated with the side oil passage 84, and the upper end is connected to the bearing holes 23 and 24, respectively. Lubrication channels 88, 88 to communicate
And a bridge member 11, a bearing cap 8 and a cylinder block 1 at one axial end of the crankshaft 9.
An oil supply passage 89 having a lower end communicating with the side oil passage 84 is formed so as to extend vertically, and the oil supply passage 89 is connected to an oil supply passage 90 formed in the pump case 13. This oil supply passage 90 communicates with the balancer shaft 21 support portion of the pump case 13,
It also communicates with a rotating shaft 44 support in the gear case 42. In a portion corresponding to the bearing holes 25, 26, 27 of the balancer shaft 22, the bridge member 11, the bearing cap 8, and the cylinder block 1 have:
The lower end communicates with the side oil passage 85 and the upper end
Oil supply passages 91 communicating with 5, 26, and 27 are respectively formed.

Oil passage 82 for guiding lubricating oil from oil filter 80 downward
Is communicated with the intermediate portion of the oil supply passage 88 at a portion corresponding to the bearing hole 24.Therefore, the lubricating oil from the oil filter 80 is supplied to the oil passages 83, 84, 85 of the bridge member 11 through the oil supply passage 88.
Will be supplied.

Next, the operation of this embodiment will be described. The rotation of the crankshaft 9 drives the first to fourth winding transmission systems T1 to T4. As a result, in the first winding transmission system T1, the valve train camshafts 30, 31 are driven with a 1/2 reduction ratio with respect to the crankshaft 9, and the water pump 32 is driven. In the second winding transmission system T2, both balancer shafts 21, 22 are driven in opposite directions with a speed increase ratio of 2/1 with respect to the crankshaft 9.

Thus, a first tensioner 46 for adjusting the tension of the first timing belt 36 in the first winding transmission system T1,
Since the second tensioner 47 for adjusting the tension of the second timing belt 39 in the winding transmission system T2 is guided by the common support shaft 45, the arrangement of the tensioner can be made compact. Moreover, in the first winding transmission system T1, the valve operating camshafts 30 and 31 and the water pump 3 which require a large driving torque are required.
In order to drive the second tension transmission system T2, a large driving load acts, but the first tensioner 46 is connected to the second tensioner.
Since the support shaft 45 is provided on the inner side in the axial direction than the support shaft 47, the load applied to the distal end side of the support shaft 45 can be minimized.

Since the first and second tensioners 46 and 47 are relatively movable in a plane perpendicular to the axis of the support shaft 45, the degree of freedom of arrangement of the first and second winding transmission systems T1 and T2 is increased. And the pressing force of the tensioners 46 and 47 on the corresponding timing belts 36 and 39 can be set individually, so that the tension setting is stabilized. Moreover, by setting the angle α formed by the pressing directions of the first and second tensioners 46 and 47 to 90 degrees or more, preferably 120 degrees or more, the load direction applied to the support shaft 45 can be shifted to reduce the overall load. In combination with the arrangement of the first and second tensioners 46 and 47, the load applied to the support shaft 45 can be reduced. The first and second tensioners 46, 47 are pressed against the outer peripheral surfaces of the first and second timing belts 36, 39 from outside thereof.
The winding angles of the first and second timing belts 36 and 39 around the pulleys on both sides, that is, the first drive pulley 28 and the driven pulley 35 for driving the water pump, and the driven pulley 37 for reverse rotation and the driven pulley 38 for normal rotation. And this is advantageous for power transmission.

Further, since the load of the second winding transmission system T2 is smaller than the load of the first winding transmission system T1, the outer ring of the second tensioner 47 is
It is possible to make the width of 58 smaller than the width of the outer ring 49 of the first winding transmission system T1, thereby reducing the projecting amount of the support shaft 45 from the cylinder block 1 and contributing to the compactness of the entire engine. can do. Further, the first tensioner 46 is configured such that a part thereof is stored
The bracket 51 is fixed to the first inner race 48, and the second inner race 56 is inserted into the first outer race 49 at least partially so that the first
Since the outer peripheral surface of the inner ring 48 is in sliding contact with the outer peripheral surface, the overall length of the first and second tensioners 46, 47 in the axial direction can be reduced as much as possible while securing the necessary width of the first and second timing belts 36, 39. This also achieves compactness.

By the way, in the second tensioners 46 and 47, the first inner ring 48
Is set larger than the outer diameter D2 of the second inner race 56, and the contact surface between the axial inner end surface of the first inner race 48 and the washer 97 due to the increase in the tightening force due to the tightening of the lock nut 66. It is possible to alleviate the increase in surface pressure and to allow the relative position change between the first and second tensioners 46 and 47 to allow the second inner ring 5 to move.
6 can be stably supported by the first inner ring 48.
In addition, a large load is locally applied from the first inner ring 46 to the cylinder block 1 due to the moment generated by the loads applied to the tensioners 46, 47 from the first and second timing belts 36, 39. Therefore, if the first inner ring 48 is directly in contact with the cylinder block 1 made of an aluminum alloy in order to reduce the weight, plastic deformation such as depression and fretting occurs in the cylinder block 1 and the lock nut 66 becomes loose. However, since the washer 97 made of a material having high buckling strength is interposed between the first inner ring 48 and the cylinder block 1, the plastic deformation of the cylinder block 1 is prevented, and therefore the lock nut 66 is prevented. Will not loosen.

By the way, the traveling speed of the second timing belt 39 in the second winding transmission system T2 is equal to the first speed in the first winding transmission system T1.
Greater than the traveling speed of the timing belt 36 (second
Times). However, in the first and second tensioners 46 and 47, the outer diameter D4 of the second outer ring 58 relative to the outer diameter D2 of the second inner ring 56
Is the outer diameter of the first outer ring 49 to the outer diameter D1 of the first inner ring 48
The ratio is set to be larger than the ratio of D3 (D4 / D2> D3 / D1). In particular, the outer diameter D3 of the first outer ring 49 is set smaller than the outer diameter D4 of the second outer ring 58. Virtual circle diameter of ball 50
D5 is set to be larger than the virtual circle diameter D6 of the second ball 57. Accordingly, the rotation speed of the second outer wheel 58 is suppressed despite the traveling speed of the second timing belt 39 being high,
In addition, the durability can be improved by arranging the second ball 57 compactly.

A spindle 45 for guiding the first and second tensioners 46, 47
Is screwed to the cylinder block 1 such that the flange portion 45d provided at the intermediate portion thereof is brought into contact with the outer surface 1a of the side wall, so that once it is mounted, there is no inclination of the axis, and the lock nut 66 is loosened. After the adjustment of the first and second tensioners 46 and 47, the first and second tensioners 46 and 47 do not tilt even when the lock nut 66 is tightened again, so that a stable tension can be set. Moreover, since the first screw portion 45a screwed to the cylinder block 1 has a larger diameter than the second screw portion 45c screwing the lock nut 66, the first screw portion 45a becomes loose when the lock nut 66 is loosened. Don't worry. Further, since the screw hole 95 for screwing the support shaft 45 communicates with the water jacket 94, the support shaft 45 is cooled by the water in the water jacket 94, and the first and second tensioners 46 and 47 are also efficiently cooled. Is done. Further, since the lock nut 66 can be operated from outside the side cover 65, the first and second lock nuts 66 can be operated.
Tension adjustment by the tensioners 46 and 47 can be performed very easily.

Further, when assembling the first and second tensioners 46 and 47,
The first tensioner 46 can be fixed by tightening the temporary tightening nut 100. Therefore, it is not necessary to assemble both the tensioners 46 and 47 at the same time, and the second tensioner 47 can be assembled after the first tensioner 46 has been assembled and temporarily fixed, so that the assembling workability is improved. After the assembly of the second tensioner 47 is completed, the temporary tightening nut 100 is removed and the lock nut 66 is loosened, so that the tensioners 46, 47 are elastically pressed against the first and second timing belts 36, 39. I will be.

In the first embodiment described above, the second bracket 59 is rotationally urged by the second tension spring 62. However, after the tension of the second timing belt 39 by the second tensioner 47 is determined, the second bracket 59 is moved. It may be fixed.

FIG. 12 and FIG. 13 show a second embodiment of the present invention, in which parts corresponding to those in the first embodiment are denoted by the same reference numerals.

An outer surface of the first tensioner 46 near the cylinder block 1 of the first inner ring 48 is provided with a fitting portion 48a formed in a cross-sectional shape other than a circle, for example, an oval shape, and a first portion for supporting the first tensioner 46 is provided. The bracket 51 '
A fitting hole 103 that fits into 48a is provided.

In this way, the shaft of the first inner ring 48 necessary for connection with the first bracket 51 'is different from the first embodiment in which the first bracket 51 is press-fitted and fixed to the first inner ring 48. The length in the direction is shortened, and the first and second tensioners 46 and 47 are brought closer to the cylinder block 1 side by that amount, which can contribute to compactness.

FIG. 14 shows a third embodiment of the present invention, in which parts corresponding to the above embodiments are given the same reference numerals.

The side cover 65 includes first and second tensioners 46, 4
A maintenance opening 104 is provided at a portion corresponding to 7, and a maintenance cover 105 for closing the opening 104 is detachably attached to the tip of the support shaft 45 by a screw member 106.

According to the third embodiment, the maintenance cover 105 can be removed without removing the entire side cover 65.
In addition, the second tensioners 46 and 47 can be visually checked, and the maintenance cover 105 can be reliably maintained in the closed state by being attached to the rigid support shaft 45 instead of the relatively weak rigid side cover 65. .

FIGS. 15 and 16 show a fourth embodiment of the present invention, in which an arm 51c having a temporary fastening slot 98 as shown in FIGS. 10 and 11 of the first embodiment is used. The first tensioner 46 may be swingably supported by the eliminated first bracket 51.

FIG. 17 shows a fifth embodiment of the present invention, and portions corresponding to the above embodiments are given the same reference numerals.

The fifth embodiment includes first and second tensioners 46 and 47.
In which the first and second timing belts 36, 39 can be pressed in the same direction. The first inner ring 48 of the first tensioner 46 and the second inner ring 56 of the second tensioner 47 are integrally formed. Formed. Moreover, the first inner ring 48 and the second inner ring
Elongated holes 54 and 61 extending in the same direction are provided in the 56 to disperse the force applied to the support shaft 45, and the support shaft 45 is inserted through the long holes 54 and 61. Moreover, since the first and second tensioners 46 and 47 move integrally and in the same direction, the second bracket 59 used in each of the above embodiments is unnecessary, and the first and second tensioners 46 and 47 used in FIGS. 14 and 15 are used. The bracket 51 is fixed to the first inner race 48.

According to the fifth embodiment, the twelfth and second tensioners
46 and 47 can be assembled to the cylinder block 1 at the same time, and the assemblability is improved.

C. Effects of the Invention As described above, according to the present invention, the first and second tensioners are supported by the common support shaft, so that the arrangement of the tensioners can be made compact, and the first and second tensioners can be mounted at the front end side of the support shaft. Since the load applied to the support shaft from the two tensioners is smaller than the load applied to the support shaft from the first tensioner at the base end side of the support shaft, the load applied to the support shaft distal end side can be suppressed to be small. The burden is effectively reduced.

According to the first aspect of the present invention, the first thread portion at the base end of the spindle screwed to the engine body has a larger diameter than the second thread portion at the tip of the spindle for screwing the lock nut. When the lock nut is loosened, the loosening of the first screw portion can be effectively prevented, and the support shaft does not come off or loosen from the engine body.

According to the second aspect of the present invention, the support shaft for guiding the first and second tensioners is screwed to the engine body such that the flange provided near the base end of the support shaft comes into contact with the outer surface of the side wall. Can be effectively prevented from tilting of the support shaft in the set state.
Also, after the adjustment of the second tensioner, the first and second tensioners do not tilt even when the lock nut is tightened again, so that stable tension setting is possible.

According to the third aspect of the present invention, since the screw hole provided on the engine body side for screwing the support shaft communicates with the water jacket, the support shaft and both tensioners are more effectively used by the water in the water jacket. Even if the screw hole communicates with the water jacket, water is prevented from leaking from the screw hole by the seal member interposed between the support shaft and the engine body.

In particular, according to the invention of claim 4, since the lock nut can be operated from the outside of the side cover, the tension adjustment by the first and second tensioners can be performed very easily.

In particular, according to the invention of claim 5, it is possible to visually check the first and second tensioners only by removing the maintenance cover without removing the entire side cover,
In addition, by attaching the maintenance cover to the rigid support shaft instead of the relatively rigid side cover, the closed state of the maintenance cover can be reliably maintained.

[Brief description of the drawings]

1 to 11 show a first embodiment of the present invention. FIG. 1 is a longitudinal side view, FIG. 2 is a view taken along the line II-II of FIG. 1, and FIG. FIG. 4 is a sectional view taken along line III-III, FIG. 4 is a sectional view taken along line IV-IV in FIGS. 1 and 5, FIG. 5 is a sectional view taken along line VV in FIG. 3, and FIG. 7 is a sectional view taken along line VI-VI of FIG. 7, FIG. 7 is a sectional view taken along line VII-VII of FIG. 3, and FIG.
9 is an enlarged sectional view taken along the line IX-IX of FIG. 2; FIG. 9A is an enlarged view of a main part of FIG. 9 showing a dimensional relationship between the first and second tensioners; 10 is a plan view of the first tensioner, FIG. 11 is a sectional view taken along the line XI-XI of FIG. 10, and FIGS. 12 and 13 show a second embodiment of the present invention.
12 is a cross-sectional plan view corresponding to FIG. 9, and FIG. 13 is a cross-sectional view of FIG.
XIII-XIII sectional view, FIG. 14 is a cross-sectional plan view corresponding to FIG. 9 of the third embodiment of the present invention, FIGS. 15 and 16 show a fourth embodiment of the present invention, 15 is a plan view corresponding to FIG. 10, FIG. 16 is a cross-sectional view taken along line XVI-XVI of FIG.
FIG. 17 is a sectional view corresponding to FIG. 9 of the fifth embodiment of the present invention. 9 ... Crank shaft, 21,22 ... Balancer shaft, 30,31 ... Valve camshaft, 36 ... First timing belt as first transmission band, 39 ... Second timing as second transmission band Belt, 45: Support shaft, 45a: First screw part, 45c: Second screw part, 45d: Flange part, 46: First tensioner, 47 ...
... second tensioner, 48 ... first inner ring, 48a ... fitting part, 4
9 first outer ring, 50 first ball as first rolling element, 51, 51 'bracket, 56 second inner ring, 57
The second ball as the second rolling element, 58... The second outer ring, 65.
... Side cover, 66 ... Lock nut, 94 ... Water jacket, 95 ... Screw hole, 96 ... Seal member, 97 ... Washer, 104 ... Maintenance opening, 105 ... Maintenance cover, 106 ... ... Screw member, E ... Engine body

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-165405 (JP, A) JP-A-62-27412 (JP, A) Fully open Showa 64-7940 (JP, U) Really open show 58- 65453 (JP, U) Japanese Utility Model Showa 62-165405 (JP, U) Japanese Utility Model Showa 62-126656 (JP, U) (58) Fields surveyed (Int. Cl. ⁶ , DB name) F16H 7/00-7 / 24 F02B 67/06

Claims (5)

(57) [Claims] An engine body in which a crankshaft, a valve operating camshaft and a balancer shaft are rotatably supported with their axes parallel to each other.
Endless first for power transmission between crankshaft and valve cam shaft
In a transmission band tension adjustment device for an internal combustion engine, a first tensioner slidingly contacting a transmission band and a second tensioner slidingly contacting an endless second transmission band for power transmission between a crankshaft and a balancer shaft are supported. A parallel support shaft has a base end screwed into the engine main body and protrudes from the engine main body. The first tensioner is disposed on the base end side of the support shaft, and the first and second tensioners are commonly supported. The first and second tensioners are provided between the first and second outer rings slidingly contacting the first and second transmission bands, the first and second inner rings through which the support shaft is inserted, and the outer and inner rings, respectively. And a lock nut, which is in contact with the axially outer end surface of the second inner race, is screwed to a tip end of a support shaft protruding from the second tensioner, and is screwed to the engine body. The first screw provided at the base end of the spindle A transmission band tension adjusting device for an internal combustion engine, wherein a diameter of a thread portion is set to be larger than a diameter of a second thread portion provided at a tip end of a spindle for screwing a lock nut. 2. A power transmission for an internal combustion engine according to claim 1, wherein a flange portion protruding radially outward to abut on the engine body is provided at a portion near a base end of the support shaft. Band tension adjustment device. 3. A screw hole provided in the engine main body for screwing a base end of the support shaft is communicated with a water jacket provided in the engine main body, and the support shaft has a seal member interposed between the water jacket and the engine main body. The transmission band tension adjusting device for an internal combustion engine according to claim 1 or 2, wherein the device is screwed into a screw hole. 4. An engine body in which a crankshaft, a valve operating camshaft and a balancer shaft are rotatably supported with their axes parallel to each other.
Endless first for power transmission between crankshaft and valve cam shaft
In a transmission band tension adjustment device for an internal combustion engine, a first tensioner slidingly contacting a transmission band and a second tensioner slidingly contacting an endless second transmission band for power transmission between a crankshaft and a balancer shaft are supported. A parallel support shaft has a base end screwed into the engine main body and protrudes from the engine main body. The first tensioner is disposed on the base end side of the support shaft, and the first and second tensioners are commonly supported. The first and second tensioners are provided between the first and second outer rings slidingly contacting the first and second transmission bands, the first and second inner rings through which the support shaft is inserted, and the outer and inner rings, respectively. A plurality of rolling elements respectively interposed in the lock nut, and a lock nut abutting on the axially outer end face of the second inner ring is screwed to a tip end of a support shaft protruding from the second tensioner, and at least operation of the lock nut is performed. Department is responsible for A transmission band tension adjusting device for an internal combustion engine, wherein the transmission band tension adjusting device is attached to and protrudes outward from a side cover that covers the first and second transmission bands. 5. An engine body in which a crankshaft, a valve operating camshaft and a balancer shaft are rotatably supported with their axes parallel to each other.
Endless first for power transmission between crankshaft and valve cam shaft
In a transmission band tension adjustment device for an internal combustion engine, a first tensioner slidingly contacting a transmission band and a second tensioner slidingly contacting an endless second transmission band for power transmission between a crankshaft and a balancer shaft are supported. A parallel support shaft has a base end screwed into the engine main body and protrudes from the engine main body. The first tensioner is disposed on the base end side of the support shaft, and the first and second tensioners are commonly supported. The first and second tensioners are provided between the first and second outer rings slidingly contacting the first and second transmission bands, the first and second inner rings through which the support shaft is inserted, and the outer and inner rings, respectively. A lock nut, which is in contact with the axially outer end surface of the second inner race, is screwed to a tip end of a support shaft protruding from the second tensioner, and is attached to the engine body. To cover the first and second drive belts The side cover is provided with a maintenance opening at a portion corresponding to the first and second tensioners, and the maintenance cover covering the maintenance opening is detachably attached to the tip of the spindle with a screw member. A transmission band tension adjusting device for an internal combustion engine, characterized by: