JPH057904U - Timing belt device - Google Patents

Abstract

(57) [Abstract] [Purpose] A timing belt device that can be applied to an engine with offsets on the left and right banks, such as a horizontally opposed engine and a V type engine, to reduce the noise of the timing belt device itself and the engine that drives it. I will provide a. [Structure] A crank sprocket 5 arranged in the center of the engine 1 having offsets in the left and right banks 2 and 3.
And one timing belt 10 is wound between the cam sprockets 8 and 9 arranged on the left and right banks 2 and 3,
A group of idlers 1 pressed against the timing belt 10.
In a timing belt device in which the support shafts 3, 14, 15, 16, 17 are fixed to the mounting bosses protruding from the left and right banks 2, 3, the timing belt device is sandwiched between the mounting bosses and the support shafts. The idler plate 21 is provided, and the attachment bosses are connected to each other via the idler plate 21.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a timing belt device suitable for a horizontally opposed engine or a V-type engine having a step in the crankshaft direction, that is, an offset, on the left and right banks.

[0002]

[Prior Art]

 In an engine equipped with an OHC (overhead camshaft) type valve operating mechanism, a camshaft driven by a timing belt device is generally known. This timing belt device has a timing belt wound between a crank sprocket fixed to the crankshaft, a cam sprocket fixed to the camshaft, and other drive pulleys for auxiliary equipment such as a water pump. A group of belt idlers including a belt tensioner are pressed against the timing belt. Here, the group of belt idlers are rotatably supported by the support shafts, respectively, and a plurality of mounting bosses are provided on the wall surface of the engine so as to fix the support shafts with bolts or the like.

Here, in a horizontally opposed engine or a V-type engine, two cam sprockets corresponding to the left and right banks are arranged on both sides of the crank sprocket as a center, and the left and right banks where these crank sprockets are arranged have a crankshaft. There is a step in the direction, that is, an offset. Therefore, in such an engine having an offset in the left and right banks, two crank sprockets b and c in front and rear are provided on the crankshaft a as shown in FIG. 5, and one crank sprocket b and one cam sprocket d are provided between them. It has been generally practiced to wind the timing belt e and similarly wind the timing belt g between the other crank sprocket c and the other cam sprocket f.

However, such a configuration requires two front and rear crank sprockets b and c, and two timing belts e and g wound around these crank sprockets, which complicates the structure and further reduces the manufacturing cost. Is also bulky. Therefore, there is also a timing belt device with a structure in which only one crank sprocket is provided on the crankshaft, and one timing belt is wound between this crank sprocket and each cam sprocket arranged on the left and right banks. It has been implemented.

[0005]

[Problems to be solved by the device]

 By the way, as described above, in the horizontally opposed engine and the V-type engine, an offset occurs in the left and right banks where the cam sprockets are respectively arranged, and therefore, one cam is provided between these cam sprockets and the crank sprockets. In the timing belt device that winds the timing belt, the protruding length of the mounting boss that protrudes on the engine wall surface to fix the support shaft of the group of idlers differs between the left and right banks, and the protruding length is long. There is a dislike for the mounting boss to lose rigidity. For this reason, the idler whose support shaft is fixed to the mounting boss vibrates due to fluctuations in the tension of the timing belt, which causes the timing belt to vibrate, increasing the noise of the timing belt device, and driving the timing belt. There was a problem that the noise of the building also increased.

Therefore, the present invention is a timing belt device that can be applied to an engine having offsets in the left and right banks such as a horizontally opposed engine and a V-type engine to reduce noise of the timing belt device itself and the engine that drives the timing belt device. The purpose is to provide.

[0007]

[Means for Solving the Problems]

 For this purpose, the present invention winds a single timing belt between a crank sprocket located in the center of the engine with offsets on the left and right banks and cam sprockets located on the left and right banks respectively. In a timing belt device in which each support shaft of a group of idlers pressed against this timing belt is fixed to each mounting boss protruding from the left and right banks, it is sandwiched between each mounting boss and each support shaft. An idler plate is provided, and the above-mentioned mounting bosses are connected to each other through the idler plate.

[0008]

[Action]

 With such a means, the mounting bosses that fix the respective support shafts of the group of idlers are connected to each other via the idler plate and are stiffened in the falling direction. As a result, vibration of the idler due to fluctuations in the tension of the timing belt is alleviated, and vibrations of the timing belt and the crank sprockets, crank shafts, cam sprockets and cam shafts that are transmitted to the timing belt are also suppressed. Therefore, the noise of the timing belt device itself and the engine that drives it is reduced.

[0009]

【Example】

 Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. For example, in FIG. 1 showing an embodiment applied to a horizontally opposed four-cylinder engine, reference numeral 1 is an engine body, and left and right banks 2 and 3 have predetermined steps along the axial direction of the crankshaft 4, that is, An offset is formed. A crank sprocket 5 fixed to the crankshaft 4 is arranged at the center of the engine body 1, and cam sprockets 8 and 9 fixed to the camshafts 6 and 7 are provided on the left and right banks 2 and 3, respectively. Are arranged. A single timing belt 10 is wound between the central crank sprocket 5 and the left and right cam sprockets 8 and 9.

The timing belt 10 is wound diagonally below the crank sprocket 5 so that the back surface of the timing belt 10 is pressed against the driving pulley 12 of the water pump 11 arranged in the left bank 2. .. Also, the two belt idlers 13 and 14 and the two toothed belts that regulate the winding shape of the timing belt 10 so that the timing belt 10 is sufficiently wound around the crank sprocket 5, the cam sprockets 8 and 9, and the drive pulley 12. The idlers 15 and 16 are provided. Here, the two belt idlers 13, 14 are arranged in the right bank 3 and are pressed against the back surface of the timing belt 10 from above and below, and the two toothed belt idlers 15, 16 are arranged in the left bank 2. And meshes with the timing belt 10 under pressure. A belt tensioner 17 that is pressed against the back surface of the timing belt 10 to adjust its tension is disposed in the left bank 2 adjacent to the crank sprockets 5.

Here, the toothed belt idler 15 will be described on behalf of a group of belt idlers including the belt idlers 13 and 14, the toothed belt idlers 15 and 16 and the belt tensioner 17, as shown in FIG. The toothed belt idler 15 is rotatably fitted to the support shaft 19 via the bearing 18. The support shaft 19 is joined to a mounting boss 20 projecting from the left bank 2 with an idler plate 21 sandwiched therebetween, and is fixed to the mounting boss 20 together with the idler plate 21 via a bolt 22. The belt idlers 13 and 14, toothed belt idler 16 and belt tensioner 17 that are similarly configured have respective support shafts 23, 24, 25 and 26 projecting from the left and right banks 2 and 3 as shown in FIG. The idler plate 21 is sandwiched between the attachment bosses 27, 28, 29, 30 and joined together, and is fixed to the attachment bosses 27, 28, 29, 30 together with the idler plate 21 via bolts 31, 32, 33, 34. ing.

The idler plate 21 is made of a metal having a predetermined thickness and has rigidity, and is bent so as to connect the mounting bosses 27, 28, 29, 30, 20. Further, the mounting bosses 27, 28, 29, 30 and 20 each having a long and short projecting amount due to the offset of the left and right banks are supported by being connected to each other by the idler plate 21.

In the timing belt device of one embodiment configured in this manner, when the crank sprocket 5 rotates together with the crankshaft 4, the rotation of the crank sprocket 5 via the timing belt 10 causes the cam sprockets 8 and 9 of the left and right banks 2 and 3 to rotate. And the camshafts 6 and 7 are driven to rotate at half the rotation speed of the crankshaft 4. Further, the water pump 11 is operated by rotationally driving the drive pulley 12 that is in pressure contact with the timing belt 10. During such rotation of the timing belt 10, the winding shape of the timing belt 10 is restricted by the belt idlers 13 and 14 and the toothed belt idlers 15 and 16, and the tension is adjusted by the belt tensioner 17. It

Here, each mounting boss to which the respective support shafts 23, 24, 25, 26, 19 of the group of idlers such as the belt idlers 13, 14, the toothed belt idlers 15, 16 and the belt tensioner 17 are fixed by bolts. 27, 28, 29, 30, 20 are mutually connected and supported by an idler plate 21. In this way, the mounting bosses 27, 28, 29, 30, 20 are stiffened in the tilting direction, so that the group of idlers 13, 14, 15, 16, 17 is affected by the tension fluctuation of the timing belt 10 and the like. Vibration is alleviated. Therefore, the vibrations of the timing belt 10, the crank sprocket 5 and the cam sprockets 8 and 9 which are transmitted to the timing belt 10 are suppressed, and the vibrations of the crankshaft 4 and the camshafts 6 and 7 are also suppressed. Therefore, the noise of the timing belt device itself and the engine that drives it is reduced.

FIG. 4 shows the sound pressure level of the engine sound measured at a position 30 cm before the crank sprocket 5, and the sound pressure level (dotted line A) when the idler plate 21 is provided as in one embodiment is It can be seen that the overall value is reduced by 2 to 3 dB over the entire engine speed as compared with the sound pressure level of the conventional example (solid line B) in which the idler plate 21 is not provided.

Although the above-described embodiment is applied to a horizontally opposed engine, the present invention can be applied to an engine such as a V-type engine or an L-type engine having an offset in the left and right banks.

[0017]

[Effect of the device]

 As described above, according to the present invention, the mounting bosses that fix the respective support shafts of the group of idlers are stiffened in the falling direction by being connected to each other via the idler plate. Therefore, vibration of the idler due to fluctuations in the tension of the timing belt is suppressed, and vibrations of the timing belt, the crank sprocket, the crankshaft, the cam sprocket, and the camshaft that are transmitted to the timing belt are also suppressed. Therefore, it is possible to reduce the noise of the timing belt device itself and the engine that drives it.

[Brief description of drawings]

FIG. 1 is a front view showing a schematic configuration of an embodiment of a timing belt device according to the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is an exploded perspective view showing the work of assembling the idler plate in the embodiment.

FIG. 4 is a graph of a noise level comparing one example with a conventional example.

FIG. 5 is an exploded perspective view of a conventional example.

[Explanation of symbols]

 1 Engine Main Body 2 Left Bank 3 Right Bank 4 Crankshaft 5 Crank Sprocket 6,7 Camshaft 8,9 Cam Sprocket 10 Timing Belt 11 Water Pump 12 Drive Pulley 13,14 Belt Idler 15,16 Toothed Belt Idler 17 Belt Tensioner 18 Bearing 19, 23, 24, 25, 26 Support shaft 20, 27, 28, 29, 30 Mounting boss 21 Idler plate 22, 31, 32, 33, 34 Bolt

Claims (1)

[Claims for utility model registration] [Claim 1] One between a crank sprocket arranged in the center of an engine having offsets on the left and right banks and cam sprockets arranged on the left and right banks respectively. In the timing belt device in which the timing belt is wound and the supporting shafts of the group of belt idlers that are pressed against the timing belt are fixed to the mounting bosses protruding from the left and right banks, A timing belt device characterized in that an idler plate sandwiched therebetween is provided, and the mounting bosses are connected to each other via the idler plate.