JPH02212647A - Transmission belt tension regulating device for internal combustion engine - Google Patents

Abstract

PURPOSE:To enable compacting of a device and to suppress a load exerted on the tip side of a support shaft to a low value by a method wherein first and second tensioners are commonly supported to a support shaft, filled in an engine body in parallel to a crank shaft, in a state that the first tensioner is arranged on the base end side of the support shaft. CONSTITUTION:A support shaft 45 filled in an engine body 1 in parallel to a crank shaft commonly and rockably supports a first tensioner 46, exerting tension on a timing belt 36 of a first wrapping transmission system T1 for driving a cam shaft and a water pump, and a second tensioner 47 of a second wrapping transmission system T2, rotationally driving a balancer shaft, in a state that the first wrapping transmission system side having a high load is arranged on the base end side of the support shaft 45. Tension is exerted on a timing belt through first and second brackets 51 and 59 through the force of tension springs 55 and 62, respectively. This constitution causes compacting of arrangement of the tensioners and enables suppression of a load exerted on the tip of the support shaft to a low value.

Description

Detailed Description of the Invention A1 Object of the Invention (]) Industrial Field of Application The present invention provides a crankshaft, a valve drive camshaft, and a balancer shaft that are rotatably supported with their axes parallel to each other. A first tensioner that slides in contact with an endless first transmission band for power transmission between the shaft and the valve camshaft, and a second tensioner that slides in contact with an endless second transmission band for power transmission between the crankshaft and the balancer shaft are supported. The present invention relates to a transmission belt tension adjustment device for an internal combustion engine.

(2) Prior art Conventionally, a pair of tensioners for adjusting the tension of two endless power transmission bands are arranged coaxially, thereby making the tensioner arrangement more compact. It is known from the publication No.

(3) Problems to be Solved by the Invention However, when a pair of tensioners are arranged on the same axis as described above, a large load is applied to the common support shaft that supports the tensioners, so the strength of the support shaft is If the tensioner for adjusting the tension of the transmission belt, which has a particularly large tension, is supported on the tip side of the support shaft,
The load applied to the base end support portion of the spindle increases.

By the way, the tension force for driving the valve camshaft is caused by the reaction force from the cam side in addition to the frictional force at the bearing of the camshaft. Hel] - Greater than tension.

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

B1 Structure of the Invention (1) Means for Solving the Problems In the present invention, a support shaft parallel to the crankshaft is installed in the engine body, and the first tensioner is placed on the base end of the support shaft. The first and second tensioners are commonly supported.

According to the configuration described in (2) Operation, the first and second tensioners are supported by a common spindle, making it possible to make the tensioner arrangement more compact. Since the load applied to the support shaft is smaller than the load applied to the support shaft from the first tensioner on the base end side of the support shaft, it is possible to keep the load applied to the front end side of the support shaft small.

(3) Embodiments Hereinafter, embodiments 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, with reference to FIGS. 1 to 11, the first aspect of the present invention will be described.
Embodiments will be described. In FIGS. 1, 2, 3, and 4, the engine body E is constructed by connecting the cylinder head 2 to the upper part of the cylinder block 1, and the lower part of the cylinder block 1. An oil pan 3 is connected to the cylinder head 2, and a head cover 4 is connected to the top of the cylinder head 2.

The cylinder head 1b is made of aluminum alloy and has two halves of a cylinder barrel part 1a and a lower half crankcase part 1b. Cylinder barrel part 1a
is provided with four cylinder bores 5 arranged in series, and pistons 6 are slidably fitted into these cylinder bores 5, respectively. In addition, a plurality of journal bearings 7 are spaced apart from each other along the arrangement direction of each cylinder bore 5 in the crankcase portion 1b.
A bearing cap 8 fixed to the lower surface of each journal bearing 7, and each journal bearing 7...
The crankshaft 9 is rotatably supported by the crankshaft 9, and the crank pin 9a of the crankshaft 9 and each of the pistons 6 are connected via connecting rods 10. Further, each of the bearing caps 8... is connected to the bridge member 1.
1 are connected together.

At one axial end of the crankshaft 9, an oil pump 12 driven by the crankshaft 9 is disposed on the outer side wall 1c of the cylinder block 1. This oil pump 12 includes a rotor 14 fixed to a crankshaft 9 within a pump case 13 attached to the side wall outer surface IC of the cylinder block 1.
An oil strainer 17 is connected to a suction port 15 provided in the pump case 13 via a suction pipe 16. Further, a discharge port 18 provided in the pump case 13 is connected to a lubricating oil passage 19 bored in the cylinder block 1 parallel to the crankshaft 9 . The other axial end of the crankshaft 9 projects slightly 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, a pair of balancer shafts 21 and 22 are located above the crankshaft 9 at substantially symmetrical positions with respect to a vertical plane passing through the axis of the crankshaft 9. They are arranged parallel and rotatable. These balancer shafts 21 and 22 suppress secondary vibrations of the engine, and one end in the axial direction is connected to the side wall outer surface 1c of the cylinder block 1.
The cylinder block 1 is inserted into the cylinder block 1 while protruding from the cylinder block 1. Both balancer shafts 21 and 22 have eccentric weight portions 21a and 2 spaced apart from each other near the other end in the axial direction.
1b; 22a, 22b, the cylinder block 1 is provided with a pair of bearing holes 23 and 24 that support a portion of one balancer shaft 21 near the other end in the axial direction, and A pair of bearing holes 25 and 26 for supporting a portion of the balancer shaft 22 near the other end in the axial direction, and a bearing hole 27 for supporting a portion of the balancer shaft 22 near the one end in the axial direction are provided.

One end of the crankshaft 9 protrudes from the pump case 13 of the oil pump 12, and the first driving pulley 28 of the first winding transmission system TI is attached to the protruding end of the crankshaft 9.
is fixed, and the second drive pulley 29 of the second winding transmission system T2 is fixed to the side farther from the cylinder block 1 than the first drive pulley 28. These driving pulleys 28, 29 are then rotationally driven in the direction indicated by the arrow in FIG.

The first winding transmission system TI connects an intake side valve drive camshaft 30 rotatably supported on the cylinder head 2 in parallel with the crankshaft 9 to drive the intake side valve drive mechanism, and an exhaust side valve drive mechanism. The cylinder head 2 is parallel to the crankshaft 9 for driving.
This is a timing transmission system for driving an exhaust side valve drive camshaft 31 rotatably supported by the cylinder block 1, and a water pump 32 attached to the side wall outer surface 1c of the cylinder block 1.
The drive pulley 28, the camshaft drive driven pulleys 33 and 34 fixed to both camshafts 30 and 31, respectively, the water pump drive driven pulley 35 fixed to the pump shaft 32a of the water pump 32, and each boo U2B. , 33, 34
．． 35, and a first timing belt 36 as an endless first transmission band.

Further, the second winding transmission system T2 includes a pair of balancer shafts 21, .
22, and is disposed on the side farther from the cylinder block 1 than the first winding transmission system T1. The second winding transmission system T2 includes a second driving pulley 29, a driven pulley 37 for reverse rotation that is interlocked and connected to one balancer shaft 21, and a driven pulley 37 for driving forward rotation of the other balancer shaft 22. Pulley 38 and each pulley 2
9.37.38, and a second timing heald 39 as an endless second transmission band.

With reference to Part 7 and Fig. 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 the pump case 13 .

That is, the gear case 42 is attached to the cylinder block 1 together with the pump case 13 by bolts 43. The driven pulley 37 for reverse rotation driving is fixed to an end of a rotating shaft 44 that projects from the gear case 42 and is rotatably supported by the gear case 42 in parallel with the balancer shaft 21 . Moreover, one end of the balancer shaft 21 protrudes into the gear case 42 while being rotatably supported by the pump case 13, and between the pump case 13 and the gear case 42, the gear 41 fixed to the end of the balancer shaft 21 and , and a gear 40 integrally provided at the inner end of the rotating shaft 44 are meshed with each other.

Therefore, the power from the reverse rotation driven pulley 37 is transmitted to the balancer shaft 21 via the gears 40, 41 that mesh with each other. That is, both balancer shafts 21, 22 are driven to rotate in opposite directions.

Referring also to FIG. 9, above the crankshaft 9, in the side wall outer surface 1c of the cylinder block 1, a threaded hole 95 that is provided in the cylinder block 1 and that communicates with the drainage jacket 94 is parallel to the crankshaft 9. It is set up as
The support shaft 45 is screwed into the screw hole 95. In other words, the support shaft 4
5 is a first screw portion 4 on the proximal end that is screwed into the screw hole 95;
5a and a shaft portion 45b are coaxially connected via a flange portion 45d extending outward in the radial direction, and a second threaded portion having a smaller diameter than the first threaded portion 45a is provided at the tip of the shaft portion 45b.
A threaded portion 45c is provided.

This 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 IC. Moreover, an annular seal member 96 is interposed between the side wall outer surface IC and the flange portion 45d to prevent water from leaking from the water jacket 94.

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

10 and 11, the first tensioner 46
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 that is in pressure contact with the outer surface of the first timing belt 36, It is swingably supported by the cylinder block 1 via a first bracket l-51.

The first inner ring 48 is formed in a cylindrical shape with a bottom open 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 end surface on the open end side, and the cylinder block 1. be done.

Moreover, the axially outer end surface of the first inner ring 48 is disposed on the inner side of the axially outer end surface of the first outer ring 49 .

Further, the washer 97 is made of a material such as an iron-based material having a higher buckling strength than the material constituting the cylinder block 1, such as an aluminum alloy.

The first bracket 51 includes a short cylindrical main body 51a that is press-fitted onto the outer surface of the proximal end of the first inner ring 48, and a main body 51.
A protrusion 51.a protrudes radially outward from the cylinder block 1 side end. b, and an arm portion 51c extending outward from the cylinder block 1 side end of the main body 51a at a position substantially symmetrical to the protrusion 51b with respect to the axis. The main body 51a has a part connected to the first tensioner 46.
The first outer ring 49 is housed in the first
It is press-fitted and fixed to the inner ring 48. Further, a support hole 52 is bored in the protrusion 51a, and when a support pin 53 implanted in the cylinder block 1 is inserted into the support hole 52, the first bracket 51, that is, the first tensioner 46 swings. It is possible to support the cylinder block 1.

An arc-shaped elongated hole 54 centered on the support pin 53 is bored in the axially outer end, that is, the closed end of the first inner ring 48 , and the shaft of the support shaft 45 is inserted into the elongated hole 54 . 45
b is inserted. Further, the other end of a first tension spring 55 whose one end is engaged with the cylinder block 1 is engaged with the arm portion 51c, and the spring force of the first tension spring 55 causes the first outer ring 49 of the first tensioner 46 to It is pressed against the first timing belt 36 from the outside, thereby applying a certain tension to the first timing belt 36.

At the tip of the arm portion 51c of the first bracket 51, a temporary tightening elongated hole 9 is formed along an arc centered on the support pin 53.
8 is provided. On the other hand, a screw shaft 99 is implanted in the side wall outer surface 1c of the cylinder block 1 and protrudes outward through a long hole 98 for temporary tightening. By screwing and tightening the first bracket 51, the swinging position of 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 that is pressed against the second timing belt 39 .

The second inner ring 56 is formed in a cylindrical shape with a bottom open to the cylinder block 1 side, and the axially inner end surface, that is, the open end surface of the second inner ring 56 is inserted into the first outer ring 49 of the first tensioner 46. The first inner ring 48
is brought into contact with the axially outer end surface of the first and second
The tensioners 46 and 47 are arranged so as to be movable relative to each other in a plane perpendicular to the axis of the support shaft 45.

Also fixed to the second inner ring 56 of the second tensioner 47 is a second bracket 59 supported by the cylinder block 1 so as to be swingable about an axis parallel to the crankshaft 9. This second bracket 59 is supported by the cylinder block 1 at its longitudinally intermediate portion, and is bent so that one end is placed close to the side wall outer surface 1c of the cylinder block 1, and avoids the first and second timing belts 36 and 39. The second tensioner 47
The outer end of the inner ring 56 is press-fitted and fixed to the other end of the second bracket 59.

A cylindrical support protrusion 101 is protruded from the side wall outer surface 1c of the cylinder block 1 to swingably support the second bracket 59, and the middle part of the second bracket 59 is attached to the tip of the support protrusion 101. The second bracket 59 is brought into contact with the sliding plate 1 (12) via the second bracket 59 and the second bracket 59 is swung by a bolt 60 that passes through the second bracket 59 and the sliding plate 1 (12) and is screwed into the support protrusion 101. Possibly supported.

An arcuate long hole 61 centered around the bolt 60 is bored in the center of the second inner ring 56, and the shaft portion 45b of the support shaft 45 is inserted into the long hole 61.

Furthermore, the other end of the second bracket 59 and the cylinder block 1
A second tension spring 62 is stretched between the
Due to the spring force of the second tension spring 62, the second outer ring 5
8 is pressed against the second timing belt 39 from the outside, thereby applying a constant tension to the second timing belt 39. The width of the second outer ring 58 in the second tensioner 47 is set smaller than the width of the first outer ring 49 in the first tensioner 46 .

In FIG. 9A, the outer diameter D1 of the first inner ring 48 is set larger than the outer diameter D2 of the second inner ring 56 (DI>D2). Further, the ratio (D4/D2) of the outer diameter D4 of the second outer ring 58 to the outer diameter D2 of the second inner ring 56 is the outer diameter D of the first inner ring 48.
The ratio of the outer diameter D3 of the first outer ring 49 to 1 (D3/Di)
(D4/D2>D3/Di), and based on such a relationship, for example, the outer diameter D3 of the first outer ring 49 is smaller than the outer diameter D4 of the second outer ring 58 (D3< D4) The virtual circle diameter D5 in which the first ball 50 is arranged is set larger than the virtual circle diameter D6 in which the second ball 57 is arranged (D5>D6).

In this way, the first timing belt 36 in the first winding transmission system T1 presses the slack side between the first driving pulley 28 and the water pump driving driven pulley 35 from the outside to the inside with the first tensioner 46. As a result, the gear case 42 is curved deeply inward, and the gear case 42 is disposed in the empty space created by the curve. Moreover, the first timing belt 36 is operated by the first tensioner 46.
The angle α between the pressing direction of the second timing belt 39 and the pressing direction of the second timing belt 39 by the second tensioner 47 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 support shaft 45
The tip of the lock nut 66 penetrates the side cover 65 and projects outward, and the lock nut 66 also projects outward from the side cover 65 to enable operation from the outside. That is, the lock nut 66 that is screwed into the second threaded portion 45c at the tip of the support shaft 45 and abuts against the outer end surface of the second inner ring 56 of the second tensioner 47 is designed so that its operating portion is disposed outside of the side cover 65. It is rotatably engaged with the side cover 65, and the lock nut 66 can be rotated from outside the side cover 65. By tightening the lock nut 66, the first and second tensioners 4
Inner rings 48 and 56 of 6.47 are movable relative to each other in a plane perpendicular to the axis of the support shaft 45 and are brought into contact with each other.

A rotating ring 67 that protrudes outward from the side cover 65 is fixed to the crankshaft 9, and a third drive pulley 68 of the third winding transmission system T3 is attached to the axially inner side of the rotating ring 67. and the fourth winding transmission system T4
A fourth drive pulley 69 is integrally provided on the axially outer side.

The third winding transmission system T3 is a transmission system for driving the AC generator 70 and air conditioner compressor 71 attached to the cylinder block 1, and is fixed to the third drive pulley 68 and the input shaft of the AC generator 70. A driven pulley 72 for driving an AC generator, a driven pulley 73 for driving a compressor fixed to the input shaft of a compressor 71 for an air conditioner, and each pulley 68, 72.7.
3 and an endless heald 74 suspended from the shaft. The fourth winding transmission system T4 is a transmission system for driving the power steering hydraulic bomb 75 attached to the cylinder head 2, and is connected to the fourth drive pulley 69 and the hydraulic pressure fixed to the input shaft of the hydraulic pump 75. It is composed of a driven pulley 76 for driving the pump and an endless belt 777 that is suspended around both pulleys 69 and 76.

Next, to explain the configuration of the lubrication oil supply system, an oil pump 12 is connected to the lubrication oil passage 19 provided in the cylinder block 1.
The lubricating oil supplied from the oil filter 80 is guided to an oil filter 80 attached to the side surface of the cylinder block 1 at a portion corresponding to the journal bearing 7 located between the two inner cylinder pores 5, 5 along the arrangement direction. Furthermore, the cylinder block 1 includes an oil passage 81 that guides the lubricating oil from the oil filter 80 upward toward the valve mechanism side, and an oil passage 82 that guides the lubricating oil downward.
and are drilled.

On the other hand, the bridge member 11 that interconnects the bearing caps 8... has a central oil passage 83 corresponding to the crankshaft 9.
and each balancer shaft 21, 22 on both sides of the central oil passage 83.
Side oil passages 84 and 85 respectively corresponding to the lateral oil passages 84 and 85 are bored parallel to the crankshaft 9.

Moreover, in the bridge member 11, each of the oil passages 83, 84.8
A communication oil passage 86 that connects the oil passages 83 to 5 communicates with each other.
The oil passages 83 to 85 are perforated at a longitudinally intermediate portion thereof to be orthogonal to each of the oil passages 83 to 85.

The bridge member 11 and each bearing cap 8...
In order to supply lubricating oil to the supporting portion of the crankshaft 9, oil supply passages 87 are formed, each extending upward and communicating with the central oil passage 83 at its lower end. In addition, the balancer shaft 210 bearing hole 23.2
4, the bridge member 11, the bearing cap 8, and the cylinder block 1 have a lower end connected to a side oil passage 84.
Oil supply passages 88 and 88 are drilled to communicate with the bearing holes 23 and 24, respectively, and the lower ends of the bridge member 11, the bearing cap 8, and the cylinder block 1 are provided at one end of the crankshaft 9 in the axial direction. An oil supply passage 89 that communicates with the side oil passage 84 extends vertically and is bored;
The oil supply passage 89 communicates with an oil supply passage 90 bored in the pump case 13 .

This oil supply path 90 is connected to the balancer shaft 2 in the pump case 13.
It communicates with the rotary shaft 44 support in the gear case 42 as well as with the rotary shaft 44 support in the gear case 42 . Bearing hole 2 of balancer shaft 22
In the part corresponding to 5.26.27, the bridge member 11,
The bearing cap 8 and the cylinder block 1 have a lower end communicating with the side oil passage 85 and an upper end communicating with the bearing hole 25,
26 and 27, respectively, are drilled therein.

Oil passage 82 that guides lubricating oil from oil filter 80 downward
are communicated with the intermediate portion of the oil supply passage 88 at a portion corresponding to the bearing hole 24, and therefore the lubricating oil from the oil filter 80 is delivered to each oil passage 83, 84, . . . of the bridge member 11 via the oil supply passage 8. 85.

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

A first tensioner 46 for adjusting the tension of the first timing belt 36 in the first winding transmission system T1;
Second timing belt 39 in second winding transmission system T2
Since the second tensioner 47 for adjusting the tension of the tensioner and the second tensioner 47 are guided by the common support shaft 45, the tensioner arrangement can be made compact. Moreover, the first winding transmission system T1
In order to drive the valve train camshaft 30.31 and the water pump 32, which require a large drive torque, a larger drive load acts on the second winding transmission system T2. Since the shaft is also axially inward and supported by the support shaft 45, the load applied to the distal end side of the support shaft 45 can be minimized.

Further, the first and second tensioners 46 and 47 are connected to the support shaft 45.
Since they are relatively movable in a plane orthogonal to the axis of the tensioners 46, 47, the degree of freedom in the arrangement of the first and first wrap transmission systems TI, T2 can be increased, and the corresponding timing belts 36, 47 of both tensioners 46, 47 can be moved relatively. 39 can be individually set, so the tension setting is stabilized. Moreover, the first
By setting the angle α between the pressing directions of the second tensioners 46 and 47 to 90 degrees or more, preferably 1.20 degrees or more, the direction of the load applied to the support shaft 45 can be shifted to keep the overall load small. '' Together with the arrangement of the two series of first and second tensioners 46 and 47, the load applied to the support shaft 45 can be suppressed to a smaller level. Also the first
The second tensioner 46.41 is pressed against the outer peripheral surfaces of the first and second timing belts 36.39 from the outside, and this is connected to the pulleys on both sides of both tensioners 46.47, that is, the first drive Boo IJ28 and driven boob IJ35 for water pump drive, driven boob IJ37 for reverse rotation drive, and driven boop IJ3 for forward rotation drive.
The winding of the first and second timing healds 36 and 39 around the timing heald 8 increases the angle, which is advantageous in terms of power transmission.

Furthermore, the load on the second winding transmission system T2 is increased by the first winding transmission system T1.
Since the load is smaller than the load of It is possible to reduce the amount of protrusion and contribute to making the entire engine more compact. Further, the first bracket 51 is fixed to the first inner ring 48 so as to be partially housed in the first outer ring 49 of the first tensioner 46, and the second inner ring 56 is at least partially inserted into the first outer ring 49. Since the first inner ring 48 slides in contact with the outer end surface of the first inner ring 48 in this manner, the first and second tensioners 46 .
The overall axial length of 47 can be made as small as possible, thereby also achieving compactness.

By the way, in the second tensioner 4647, the first inner ring 4
The outer diameter DI of the second inner ring 56 is set larger than the outer diameter D2 of the second inner ring 56, and as the tightening force increases due to tightening of the lock nut 66, the axially inner end surface of the first inner ring 48 and the washer 97
The second inner ring 56 can be stably supported by the first inner ring 48 by alleviating the increase in contact surface pressure between the second inner ring 56 and the second inner ring 48 by allowing changes in the relative positions of the first and second tensioners 46 and 47. Can be done. Moreover, the moment i generated by the load applied from the first and second timing belts 36.39 to each tensioner 46.47
A large load is applied locally to the cylinder block 1 side. For this reason, if the first inner ring 48 were brought into direct contact with the cylinder block 1 made of aluminum alloy to reduce weight, plastic deformation such as caving and fretting would occur in the cylinder block 1, causing the lock nut 66 to loosen. Although this may occur, a washer 97 made of a material with high buckling strength is installed 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 does not loosen.

By the way, the running speed of the second timing belt 39 in the second winding transmission system T2 is higher than the running speed of the first timing belt 36 in the first winding transmission system T1 (about 2
times). However, the first and second tensioners 46.47
, the second outer ring 5 with respect to the outer diameter D2 of the second inner ring 56
8 is larger than the ratio of the outer diameter D3 of the first outer ring 49 to the outer diameter D1 of the first inner ring 48 (D4/
D2>D3/DI) 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, and the virtual circular diameter D5 of the first ball 50 is set smaller than the outer diameter D4 of the second outer ring 58. It is set larger than the virtual circle diameter D6 of the two poles 57. Therefore, even though the running speed of the second timing belt 39 is high, the rotational speed of the second outer ring 58 can be suppressed, and the second balls 57 can be arranged compactly to improve durability.

Support shaft 4 that guides the first and second tensioners 46 and 47
5 is screwed onto the cylinder block 1 so that the flange portion 45d provided in the middle thereof is in contact with the side wall outer surface 1a, so that once it is installed, there is no inclination of the axis, and the lock nut 66 can be loosened. After adjusting the first and second tensioners/16.47, tighten the lock nut 66.
Even when retightening (-1), the first and second tensioners 46 and 47 do not tilt, making it possible to set a stable tension.Moreover, the first threaded portion 45a that is screwed into the cylinder block 1 is connected to the lock nut 66. The second threaded portion 45 that screws together the
Since the diameter is larger than c, there is no fear that the first threaded portion 45a will loosen when the lock nut 66 is loosened. Furthermore, the support shaft 4
Since the threaded hole 95 for screwing the tensioner 5 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 4.6.47 are also efficiently cooled. Ru. Further, since the lock nut 66 can be operated from the outside of the side cover 65, the tension adjustment by the first and second tensioners 46, 47 can be performed extremely easily.

Furthermore, when assembling the first and second tensioners 46, 47, the first tensioner 46 can be fixed by tightening the temporary tightening nut 1 (10).Therefore, it is not necessary to assemble both tensioners 46, 41 at the same time. After the first tensioner 46 has been assembled and temporarily fixed, the second tensioner 47 can be assembled, improving the ease of assembly.

After completing the assembly of the second tensioner 47, both tensioners 4, 6, 41 are attached to the first and second timing bells 1-36, 39 by removing the temporary tightening nut 1 (10) and loosening the lock nut 66. It will come into contact with elastic pressure.

In the first embodiment described above, the second bracket 59 is rotationally biased by the second tension spring 62, but after the tension of the second timing heald 39 is determined by the second tensioner 47, the second bracket 1- 59 may be fixed.

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

A fitting part 48a formed in a cross-sectional shape other than circular, for example, an oval shape, is provided on the outer surface of the first inner ring 48 of the first tensioner 46 closer to the cylinder block 1. The bracket 51' is provided with a fitting hole 1 (13) that fits into the fitting portion 48a.

By doing this, the first bracket 51 is connected to the first inner ring 48.
Compared to the first embodiment described in Section 2, the axial length of the first inner ring 48 required for connection with the first bracket 51' is shortened, and the length of the first inner ring 48 is shortened by that amount.
and the second tensioner 46, 47 in the cylinder block 1
By placing it close to the side, it can contribute to compactness.

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

The side cover 65 includes first and second tensioners 46.
．． Maintenance opening 1 (14
A maintenance cover 1 (15) that closes the opening 1 (14) is removably attached to the tip of the support shaft 45 by a screw member 106.

According to this third embodiment, it is possible to visually check the first and second tensioners 46, 47 by simply removing the entire side cover 65, and moreover, it is possible to visually check the first and second tensioners 46, 47 by simply removing the entire side cover 65. Moreover, instead of using the side cover 65, which has relatively low rigidity, it is possible to visually check the first and second tensioners 46, 47. By attaching it to the maintenance cover 1 (15), the closed state of the maintenance cover 1 (15) can be maintained reliably.

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

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

This fifth embodiment has first and second tensioners 46, 4
7, the first and second timing belts 36 and 39 can be pressed in the same direction, and the first inner ring 48 of the first tensioner 46 and the second inner ring 56 of the second tensioner 47 are Formed in one piece. Moreover, the first inner ring 4
8 and the second inner ring 56 are provided with long holes 54 and 61 that extend in the same direction in order to disperse the force applied to the support shaft 45, and the support shaft 45 is inserted through these long holes 54 and 61. Moreover, the first and second tensioners 46.

47 move integrally in the same direction, the second bracket 59 used in each of the above embodiments is unnecessary, and the bracket 51 used in FIGS. 14 and 15 is fixed to the first inner ring 48. be done.

According to this fifth embodiment, the twelfth and second tensioners 46 and 47 can be assembled to the cylinder block 1 at the same time, and the assembly can be carried out at any time.

C8 Effects of the Invention As described above, according to the present invention, a support shaft parallel to the crankshaft is installed in the engine body, and the first tensioner is disposed on the base end side of the support shaft. Since the first and second tensioners are supported in common, the tensioner arrangement can be made compact and the load applied to the tip end of the support shaft can be kept small.

[Brief explanation of the drawing]

1 to 11 show a first embodiment of the present invention, in which FIG. 1 is a vertical sectional side view, FIG. 2 is a view taken along the line ■-■ in FIG. 1, and FIG. Cross-sectional view along the ■-■ line in the figure, Figure 4 is the 1st
Figure 5 is a cross-sectional view taken along the line IV-TV in Figure 5, the fifth is a cross-sectional view taken along the line V-V in Figure 3, and Figure 6 is a cross-sectional view taken along the ■-■ line in Figure 3.
Figure 7 is a sectional view taken along the line ■-■ in Figure 3, and Figure 8 is a cross-sectional view taken along the line ■ in Figure 3.
9 is an enlarged sectional view taken along line IX-IX in FIG. 2, FIG. 9A is an enlarged view of the main part of FIG. FIG. 10 is a plan view of the first tensioner, FIG. 11 is a sectional view taken along the line XI>1 in FIG. A cross-sectional plan view corresponding to FIG. 9, FIG. 13 is a cross-sectional view taken along the xm-xm line in FIG. 12, and FIG. 14 is a cross-sectional plan view corresponding to FIG. 9 of the third embodiment of the present invention.
15 and 16 show a fourth embodiment of the present invention, and FIG. 15 is a plan view corresponding to FIG.
6 is a sectional view taken along line xvh-x■ in FIG. 15, and FIG. 17 is a sectional view corresponding to FIG. 9 of the fifth embodiment of the present invention. 9... crankshaft, 21. ．． 22...Parantha axis,
30.31... Valve drive camshaft, 36... First timing belt as a first transmission band, 39... Second timing belt as a second transmission band, 45... Support shaft, 4. 5
a...First threaded part, 45c...Second threaded part, 45
d...Flange portion, 46...First tensioner, 47
...Second tensioner, 48...First inner ring, 48a.
. . . Fitting portion, 49 . . . First outer ring, 50 . . . First ball as the first rolling element, 51, 5], ' . . . Bracket, 56 . . . Second inner ring, 57 . . . -Second ball as second rolling element, 58...Second outer ring, 65...Zite copper, 66...Lock nut, 94...Water jacket, 95...Threaded hole, 96...Seal Part, 9
7... Washer, 1 (14... Maintenance opening, 1 (15... Maintenance cover, 106...
Screw member, E...engine body

Claims (17)

[Claims] (1) The engine body, in which the crankshaft, valve camshaft, and balancer shaft are rotatably supported with their axes parallel to each other, slides into contact with the endless first transmission band for power transmission between the crankshaft and the valve camshaft. In a transmission band tension adjustment device for an internal combustion engine in which a first tensioner and a second tensioner that slides in sliding contact with an endless second transmission band for power transmission between a crankshaft and a balancer shaft are supported, a support shaft parallel to the crankshaft is supported. Transmission band tension for an internal combustion engine, which is installed in the engine body, and the first tensioner is disposed on the base end side of the support shaft, and the first and second tensioners are commonly supported by the support shaft. Adjustment device. (2) The first and second tensioners have first and second outer rings that are in sliding contact with the first and second transmission bands, respectively, first and second inner rings through which the support shafts are inserted, and a space between each outer ring and each inner ring. and a plurality of rolling elements interposed respectively in the second
The power transmission band tension adjustment device for an internal combustion engine according to item (1), wherein the lock nut that abuts the axially outer end surface of the inner ring is screwed onto the tip of the support shaft protruding from the second tensioner. (3) The transmission band tension adjusting device for an internal combustion engine according to item (2), wherein the width of the second outer ring is set smaller than the width of the first outer ring. (4) The power transmission band tension adjusting device for an internal combustion engine according to item (2) or item (3), wherein the first and second inner rings are integrally formed. (5) The transmission band tension adjustment device for an internal combustion engine according to item (4), wherein the first and second inner rings are each provided with an elongated hole through which the support shaft is inserted. (6) Items (2) and (3), characterized in that the outer diameter of the first inner ring is set larger than the outer diameter of the second inner ring.
The transmission belt tension adjustment device for an internal combustion engine according to item (4) or item (5). (7) The ratio of the outer diameter of the second outer ring to the outer diameter of the second inner ring in the second tensioner is set to be larger than the ratio of the outer diameter of the first outer ring to the outer diameter of the first inner ring in the first tensioner. Items (2), (3), and (
The transmission belt tension adjustment device for an internal combustion engine according to item 4), item (5), or item (6). (8) The outer diameter of the first outer ring is set smaller than the outer diameter of the second outer ring, and the diameter of the virtual circle in which the first rolling element is arranged is set larger than the diameter of the virtual circle in which the second rolling element is arranged. The transmission band tension adjusting device for an internal combustion engine according to item (7), characterized in that: (9) The base end of the spindle is screwed into the engine body, and the diameter of the first threaded portion provided at the base end of the spindle to be screwed into the engine body is the same as the diameter of the first threaded portion provided on the base end of the spindle to be screwed into the engine body. The power transmission band tension adjusting device for an internal combustion engine according to item (2), wherein the diameter is set larger than the diameter of the second threaded portion provided at the tip. (10) Transmission band tension of the internal combustion engine according to item (9), characterized in that a flange portion protruding radially outward so as to come into contact with the engine body is provided on a portion near the base end of the support shaft. Adjustment device. (11) A screw hole provided in the engine body to screw the base end of the support shaft communicates with the water jacket provided in the engine body, and the support shaft is screwed with a sealing member interposed between it and the engine body. The transmission band tension adjusting device for an internal combustion engine according to item (9) or item (10), characterized in that the device is screwed into the hole. (12) A fitting portion having a cross-sectional shape other than circular is provided on the outer surface of the first inner ring of the first tensioner closer to the engine body, and a bracket supported by the engine body is fitted into the fitting portion. The transmission belt tension adjustment device for an internal combustion engine according to item (2), characterized in that: (13) The transmission belt tension of the internal combustion engine according to item (2) or item (12), wherein the bracket is fixed to the first inner ring by inserting at least a portion thereof into the first outer ring. Adjustment device. (14) Item (2) characterized in that a washer made of a material having higher buckling strength than the material constituting the engine body is interposed between the axially inner end surface of the first inner ring and the engine body.
Transmission belt tension adjustment device for an internal combustion engine as described in 2. (15) Item (2) characterized in that the first and second transmission bands are covered with a side cover attached to the engine body, and at least the operating portion of the lock nut projects outward from the side cover. The transmission belt tension adjustment device for the internal combustion engine described above. (16) The first and second transmission bands are covered by a side cover attached to the engine body, and a maintenance cover covers a maintenance opening provided in the side cover at a portion corresponding to the first and second tensioners. The power transmission band tension adjustment device for an internal combustion engine according to item (1), item (2), or item (15), characterized in that the device is removably attached to the tip of the support shaft by a screw member. (17) The first and second tensioners are connected to the first and second tensioners.
(1) characterized in that it is pressed against the outer circumferential surface of the transmission band;
Transmission belt tension adjustment device for an internal combustion engine as described in 2.