JPS6146284Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a timing belt tensioner device for a V-type engine equipped with an automatic tension adjustment function.

(Prior Art) As a prior art in the technical field to which the present invention pertains, there is, for example, a timing belt tensioner device for a V-type engine described in Japanese Utility Model Application No. 58-9554.

However, this conventional timing belt tensioner device uses a timing belt that is stretched between a pair of camshaft pulleys (toothed pulleys) and crankshaft pulleys (toothed pulleys) provided on the left and right banks of a V-type engine. Between the pair of camshaft pulleys of the (toothed belt), the free portion of the timing belt is biased and displaced in the thickness direction of the timing belt (in other words, the free portion of the timing belt is displaced between the pair of camshaft pulleys of the Since the idler pulley is arranged to adjust the tension of the timing belt by changing the effective length of the timing belt, the timing belt is pulled between the pair of camshaft pulleys by the urging force of the idler pulley. When the timing belt is bent, the effect of the timing belt bending directly appears as a change in the length of the timing belt stretched between the pair of camshaft pulleys, causing a shift in the rotational phase of the pair of camshaft pulleys. There was a problem in that the opening and closing timings of the valves provided in the left and right banks and driven to open and close by the camshafts did not match between the two banks, impairing the operating characteristics of the engine.

In addition, in this conventional timing belt tensioner device, the winding angle of the timing belt around each pulley is set to be relatively large, so the number of meshing teeth between the timing belt and each pulley that mesh with each other is small. As a result, there is a problem in that tooth skipping occurs between the timing belt and each pulley, and the rotational phase between the crank pulley and the pair of cam pulleys tends to shift.

(Purpose of the invention) The present invention was made in an attempt to solve or improve the problems pointed out in the prior art section above. In addition to preventing deviations in opening/closing timing between the two banks of valves provided in each bank, the timing belt wrap angle around each pulley is made as large as possible to prevent crankshaft problems caused by timing belt tooth skipping. The purpose of this is to prevent a shift in the rotational phase between the pulley and the pair of camshaft pulleys, and to maintain the tension of the timing belt at a set tension at all times.

(Means for Achieving the Object) As a means for achieving the above object, the present invention provides the following features: (1) Each of the above-mentioned A total of three idlers are provided, one for each, which act to press the timing belt stretched between the pulleys in the direction of its inner peripheral surface, and (2) among the three idlers, the rotation of the crankshaft pulley is The idler, which is located on the slack side with respect to the direction, is composed of a tensioner with an automatic tension adjustment function.

(Function) In the present invention, a total of three idlers are provided, one each at an intermediate position between a total of three pulleys: a crankshaft pulley and a pair of camshaft pulleys provided on the left and right banks, respectively, and a total of three idlers are provided. The free portions (unsupported portions) between each pulley are greatly bulged inward of the timing belt by each idler to maximize the winding angle of the timing belt around each pulley. This provides the effect of increasing the number of meshing teeth between the pulleys and preventing deviations in rotational phase between the pulleys due to tooth skipping of the timing belt.

In addition, by using a tensioner with an automatic tension adjustment function as the idler located on the slack side with respect to the rotational direction of the crankshaft pulley among the three idlers mentioned above, the belt tension adjustment function by the tensioner (i.e. This method prevents the length of the timing belt from changing between the pair of camshaft pulleys due to changes in the effective length of the timing belt (changes in the effective length of the timing belt), and adjusts the opening/closing timing of the valves provided in both banks. Two functions can be obtained at the same time: the function of always matching the two banks, and the function of automatically maintaining the tension of the timing belt at the set tension at all times.

(Embodiment) Hereinafter, a preferred embodiment of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 shows a V-type automobile engine 1 equipped with a tensioner device according to an embodiment of the present invention. This engine 1 has a cylinder block 21 having a pair of left and right banks, that is, a first bank 2 and a second bank 12, which are inclined in a V-shape.
A first cylinder head 3 and a second cylinder head 13 are provided at the upper end of each bank 2, 21 of the cylinder block 21, respectively, and a first head cover 4 is provided at the upper end of the first cylinder head 3 and second cylinder head 13, respectively. The second head covers 14 are each fastened and fixed. Also, the cylinder block 21
An oil pan 22 is attached to the lower end. As shown in FIGS. 1 and 2, a cover member 23 is assembled between the lower end of the cylinder block 21 and the oil pan 22. The cover member 23 has a sealing function to maintain a seal between the two.

The lower part of the front end surface 1a of this engine 11 (i.e.
A crankshaft 24 protrudes from the lower part of the cylinder block 21, passing through the cover member 23 in the inner and outer directions. A toothed crankshaft pulley 27 is attached to the protruding end of the crankshaft 24.

On the other hand, of the first cylinder head 3 and the second cylinder head 13, the first cylinder head 3 has a first camshaft 6 that opens and closes the intake and exhaust valves of the cylinders on the first bank 2 side. Second camshafts 16 are arranged in the head 13 to open and close the intake and exhaust valves of the cylinders on the second bank 12 side. A first camshaft pulley 7 with teeth is attached to the first camshaft 6, and a second camshaft pulley 17 with teeth is attached to the second camshaft 16, respectively. That is, the first camshaft pulley 7, the second camshaft pulley 17, and the crankshaft pulley 27 are as follows:
They are arranged in such a relative positional relationship that they are located at each vertex of an inverted triangle.

A toothed timing belt 26 is stretched between three pulleys, the crankshaft pulley 27, the first camshaft pulley 7, and the second camshaft pulley 17, which are arranged in an inverted triangle shape.

Further, there are three free parts (non-meshing support parts) of the timing belt 26, namely, a first free part 26a located between the first camshaft pulley 7 and the second camshaft pulley 17, and a first free part 26a located between the crankshaft pulley 27 and the second camshaft pulley 17. The second free part 26b located between the first camshaft pulley 7 and the third free part 26c located between the crankshaft pulley 27 and the second camshaft pulley 17 are connected to the first The idler 31, the second idler 32, and the third idler 33 press the belt toward the inner peripheral surface thereof.

The center of rotation of each idler 31, 32, 33 is located closer to the timing belt 26 than the external tangent line _L1 , _L2 , _L3 between each pulley 7, 17, 27, respectively.
It is located closer to the center of the
The timing belt 26 has each pulley 7, 17,
27 in a substantially Y-shape. Therefore, the winding angle of the timing belt 26 around each pulley 7, 17, 27 is the outer tangent line L ₁ ,
The wrap angle is made as large as possible than the included angle between L ₂ and L ₃ , and the number of meshing teeth between the timing belt 26 and each pulley 7, 17, 27 is increased as much as possible. It will be done. As a result, the meshing engagement between the two becomes more reliable, teeth skipping of the timing belt 26 is prevented, and the timing belt 26
This prevents rotational phase shifts between the pulleys due to tooth skipping.

On the other hand, among the idlers 31, 32, and 33, the first idler 31 and the second idler 32 are both fixed idlers, but the third idler 3
Reference numeral 3 is made into a movable idler by means as described below, and is made to act as a tensioner for adjusting the belt tension of the timing belt 26. That is, the third idler 33 supports a fulcrum pin 4 provided on the cylinder block 21 as shown in FIGS. 1 and 2.
The timing belt 26 is rotatably attached to a swinging end 43a of a rotary lever 43 rotatably supported on the timing belt 26. The third free portion 26c of the third free portion 26c is configured to be moved in the direction of displacing the third free portion 26c in the inward and outward directions.

On the other hand, an actuator 52 of a damper 50 that provides an automatic tension adjustment function to the third idler is brought into contact with a pressing portion 44 formed on the rotary lever 43. This damper 50 includes a spring (not shown) that always presses the actuator 52 against the pressing part of the rotary lever 43 with a predetermined pressing force, and a spring (not shown) in the cylindrical casing 51. It is constructed of a known damper device equipped with a damper mechanism that suppresses sudden forward and backward displacement by the flow resistance of sealed oil, and when the belt tension of the timing belt 26 falls below a preset tension. In this case, the actuator 52 is projected by the spring force of the spring and the third idler 33 is displaced in the direction of arrow A, thereby acting to restore and maintain the belt tension of the timing belt 26 to the set tension.

Therefore, when such a damper 50 is biased against the third idler 33, the belt tension of the timing belt 26 is not only automatically maintained at the set tension by the biasing force of the damper 50, but also
The belt tension of the timing belt 26 is adjusted by changing the belt length of the third free portion 26c which is on the slack side with respect to the rotational direction of the crankshaft pulley 27. Therefore, a change in belt length between the first free portion 26a and the second free portion 26b located on the tension side is prevented. Therefore, the third
The crankshaft pulley 27, the first camshaft pulley 7, and the second camshaft pulley 17, regardless of the operation of the idler 33 (in other words, the state of change in the belt length of the third free portion 26c).
The rotational phase of each of the banks 2, 2, and 2 is always maintained at an appropriate phase, and not only is a deviation in valve opening/closing timing between the first bank 2 and the second bank 12 prevented from occurring, but also the rotational phase of each bank 2, This also prevents deviations in the opening/closing timing of the 12 valves. That is, each bank 2,
The opening and closing timings of the intake and exhaust valves provided in each of the 12 cylinders are always maintained at appropriate timings.

Note that this damper 50 has a casing 51
a pocket portion 53 formed on the cover member 23;
The cover member 23 is detachably attached to the cover member 23 by a simple means of being inserted into the cover member 23. That is, the damper 50 has the casing 5 inside the pocket portion 53.
1 is inserted and the outer circumferential surface 51b of the casing 51 and the inner circumferential surface 53b of the pocket portion 53 are engaged in the radial direction of the casing 51, thereby restricting the movement in the lateral direction, and the distal end surface of the casing 51 51a is abutted against the bottom surface 53a of the pocket portion 53, and the actuator 52 is brought into contact with the pressing portion 44 of the rotary lever 43, and is housed in the casing 51 between the pressing portion 44 and the bottom surface 53a of the pocket portion. Movement in the axial direction is restricted by applying a spring force from the spring (not shown). Therefore, the engagement between the third idler 33 and the timing belt 26 is released, and the idler 33 is rotated integrally with the rotary lever 43 in the direction of arrow C, so that the rotary lever 43 and the actuator of the damper 50 are rotated. By disengaging the actuator 52 from the actuator 52 in the advancing and retracting direction, the damper 50 can be moved into the pocket portion 5 without removing bolts or the like.
3, which makes it easier to maintain and inspect the damper.

Incidentally, in FIG. 2, reference numeral 54 denotes a belt cover disposed to cover the outside of the timing belt 26.

(Effects of the invention) As is clear from the above explanation, the timing belt tensioner device for a V-type engine according to the invention has the following features: The intermediate position between the respective pulleys of the timing belt being stretched is urged by three idlers that respectively apply a pressing force to the timing belt in the direction of its inner circumferential surface. Since the winding angle around each pulley is made as large as possible, the winding angle of the timing belt around the pulley is made as large as possible, as in the conventional timing belt tensioner device (for example, Japanese Utility Model Application No. 58-9554). The meshing engagement force between each pulley and the timing belt is improved compared to the case where the timing belt is relatively small, and as a result, timing belt tooth skipping is prevented, and the valve opening and closing timing of each bank relative to the crankshaft is adjusted to the appropriate timing. maintained.

(2) Among the above idlers, the idler located on the loose side with respect to the rotational direction of the crankshaft pulley is made to act as a tensioner for adjusting belt tension, so the belt length changes due to the belt tension adjustment action. The effect of (3) Since the idler, which acts as a tensioner, has an automatic tension adjustment function, the belt tension of the timing belt is maintained at an appropriate tension over a long period of time. It has the effect of

[Brief explanation of the drawing]

FIG. 1 is a front view of a V-type engine equipped with a timing belt tensioner device according to an embodiment of the present invention, and FIG. 2 is a longitudinal cross-sectional view of the main part of FIG. 1. 1...V-type engine, 2,12...Bank, 3,1
3...Cylinder head, 4,14...Head cover,
6, 16...Camshaft, 7, 17...Camshaft pulley, 21...Cylinder block, 22...Oil pan, 23...Cover member, 24...Crankshaft, 26...Timing belt, 27...Crankshaft pulley, 31, 32, 33 …Idler,
50...damper, 52...actuator.

Claims (1)

[Scope of utility model registration request] In a V-type engine in which the rotation of the crankshaft pulley is transmitted via a timing belt to two camshaft pulleys arranged in the cylinder head portions of left and right banks, between the two camshaft pulleys and between the two camshaft pulleys. Idlers are provided at a total of three locations between the crankshaft pulley and each idler that applies a pressing force in the direction of the inner peripheral surface of the timing belt. A timing belt tensioner device for a V-type engine, characterized in that the located idler is a tensioner with an automatic tension adjustment function.