JPH0738751Y2 - Belt tensioning device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a seal structure of a belt tensioning device in a pulley belt transmission system from a crankshaft to a driven part such as a camshaft in an internal combustion engine.

[Conventional technology]

In an internal combustion engine, a pulley belt transmission system may be adopted to transmit the rotation of the crankshaft to a driven part such as a camshaft. As the belt, a combination of a timing belt and a timing pulley is adopted in order to prevent the timings of the crank shaft and the cam shaft from shifting. A tension pulley for maintaining the belt at a predetermined tension and a tension control mechanism for urging the tension pulley are provided.
Since the timing belt is vulnerable to foreign matter such as lubricating oil of the internal combustion engine, a timing belt cover is attached to the front surface of the cylinder block to prevent the foreign matter from entering. As a tension control mechanism, in Japanese Utility Model Publication No. 56-49451, a main body is fixed on a cylinder block, and a rod is arranged in the main body so as to be retractable by elastic force. The elastic force from the rod is transmitted to the timing belt via the tension pulley,
The tension of the belt will be controlled. Then, in order to facilitate the wearing of the belt during assembly, a bolt is provided as a means for holding the rod in the retracted state, and when the bolt is loosened after the assembly is completed, the rod is advanced by the elastic force, and the timing is adjusted by the tension pulley. Appropriate tension is applied to the belt. The body can be externally inserted into an insertion hole formed in the cylinder block.
Therefore, the tension adjusting mechanism can be attached after the timing belt cover is attached. This is to facilitate replacement of the tension adjusting mechanism. Further, there is an advantage that the timing mark can be easily adjusted during maintenance. That is, the timing belt cover is composed of separate upper and lower parts, and if the tension adjusting mechanism is removed, the position of the timing pulley on the camshaft can be adjusted by removing only the upper timing belt cover. Can be done.

[Problems to be solved by the device]

In the case of the conventional technique, as described above, the means for contracting and holding the rod before assembly is the bolt, and by loosening the bolt after the assembly is completed, the rod extends and the tension pulley takes the original position. And, for the purpose of sealing, the part where the bolt is removed is plugged. This work consists of multi-step processes and has a problem that workability is not good. Therefore, the rod has a structure that is slidable via a sealing material, and
There is a structure in which a pop-out prevention pin is provided, the rod is held in a contracted state by the pin before assembly, the pin is pulled out at the time of assembly, and the rod is projected through a sealing material (for example, JP-A-62-283245). reference). In this case, the pop-out prevention pin is provided on a part of the main body which is different from the sealing material. The pop-out prevention pin is inserted into the rod through an elastic material embedded in the recess of the main body for sealing.

However, in this structure, when the pop-out prevention pin is pulled out and the rod is popped out, the pin hole of the elastic material and the pin hole of the main body remain aligned, and there is a risk of foreign matter entering.

An object of the present invention is to solve the problems of the prior art and to avoid the possibility of foreign matter entering through the pin hole after the pop-out prevention pin is removed.

[Means for Solving the Problems]

According to the present invention, the pulley belt transmission system that connects the rotational force from the crankshaft to the driven portion such as the camshaft and the tension pulley urged by the elastic tension control mechanism for controlling the tension of the belt are provided. The tension control mechanism is covered from the outside by a belt cover fixed to the front surface of the cylinder block, and the tension control mechanism cooperates with a main body that is inserted into the insertion hole of the cylinder block from the outside and elastically retractable with respect to the main body. The tension member for applying tension to the belt, the detachable pop-out prevention pin that holds the tension member in the contracted position in the main body before mounting, the insertion hole of the pop-out prevention pin, and the sliding portion of the tension member. And elastic means for sealing the insertion part of the main body into the insertion hole of the cylinder block, the elastic means being formed as a bottomed cylindrical seal member. The seal member is mounted by sandwiching the opening-side end surface between the seating surface of the main body and the mating mounting seat surface, and the sliding portion of the tension member seals against the bottom surface of the seal member. The slide-out prevention pin is inserted into the pin hole of the sliding portion of the tension member through the pin hole of the cylindrical portion of the seal member and the pin hole of the insertion portion before mounting, and the seal The end face on the opening side of the member has a gap between it and the seating surface of the opposing body before it is attached to the mating mounting seating surface, and seals when the body is attached to the mating mounting seating surface by pulling out the pop-out prevention pin. A belt tensioning device is provided, wherein the member is deformed by the amount of the gap, and the pin hole of the cylindrical portion and the pin hole of the insertion portion are displaced from each other.

〔Example〕

FIG. 5 is a schematic view of the pulley belt system of the present invention as seen from the front of the cylinder block. 10 is a crank shaft, 12 is a crank pulley, 14 is an intake cam shaft, 16 is an intake cam pulley, 18
Is an exhaust cam shaft, 20 is an exhaust cam pulley, and 22 is a tension pulley. A timing belt 24 is wound around the crank pulley 12, the intake cam pulley 14, and the exhaust cam pulley 18.
The tension pulley 22 is provided on a lever 28 which is rotatable around a pin 26, and the tension adjusting mechanism 30 of the present invention urges the lever 28 to rotate around the pin 26 in the clockwise direction in the drawing. As a result, the tension of the timing belt 24 is adjusted to a predetermined value. In FIG. 5, 29 is a timing belt.
It is a raised portion integrally formed with the cylinder block so as to surround 24, and a timing belt cover (not shown) is placed on the raised portion 29 and fixed to the cylinder block with bolts. Reference numeral 32 indicates one of the boss portions formed with screw holes to receive the bolt. The cylinder block is integrally formed with a seat portion 40 for receiving the tension adjusting mechanism 30. As shown in FIG. 1, the tension adjusting mechanism 30 has a tubular body.
42, a piston 44 that slides in the main body, a rod 46 at the tip of the piston 44, a coil spring 48 that urges the piston 44 in the main body 42 in the direction of jumping out of the main body, and a lower lid portion 50. . Cylinder block S in FIGS. 4 and 5
The seat portion 40 has a cylindrical insertion hole 52, and the main body 42 is inserted into the insertion hole 52.
Is inserted. On the other hand, the main body 42 has a flange portion 42a, and the flange portion 42a comes into contact with the receiving surface of the seat portion 40 when the tip of the main body 42 is inserted into the insertion hole 52. The mounting bolt 56 is inserted through a bolt insertion hole 58 formed in the flange portion 42a, and its tip is a screw hole formed in the seat portion 40.
Screwed into 60. As a result, the tension adjusting mechanism 30 is attached to the cylinder block.

In FIG. 1, reference numeral 64 denotes a pop-out prevention pin, which is provided before the assembling of the tension adjusting mechanism 30 to the cylinder block.
64 is inserted into the pin hole 70 of the rod 46 via the pin hole 66 of the main body. This state corresponds to the contracted state of the rod 46, and the rod 70 is located apart from the lever 28. Therefore, the tension pulley 22 does not apply tension to the timing belt 24. By assembling the tension adjusting mechanism 30 to the seat 40 of the cylinder block with the bolt 56 and then pulling out the pin 64, the spring 48 advances the rod 46, and the tip thereof engages with the lever 28 as shown in FIG. The lever rotates clockwise around the pin 26, the engagement between the tension pulley 22 and the timing pulley 24 is deepened, and the tension pulley 24 is adjusted to the desired tension.

According to the present invention, an elastic seal member 80 is provided for sealing the sliding portion of the rod 46, the insertion portion of the main body 42 and the insertion portion of the pin 64. The elastic seal member 80 has a bottomed tubular portion 82 that covers the tip of the main body 42, a plurality of lip portions 84 that are formed on the outer periphery of the tubular portion 82, and rises above the tubular portion 82 at the insertion point of the pin 64. And a raised portion 88 formed as a result.
The raised portion 88 has a shape that engages with a U-shaped notch 90 formed in the seat portion 44 of the cylinder block without a gap (see FIGS. 2 and 4).

Prior to assembly, the pin 64 is attached to hold the rod 46 in the retracted position as described above.
As shown in FIGS. 5 and 5, the tension adjusting mechanism 30 is inserted,
At this time, the raised portion 88 of the seal member 80 has the cylinder block S
It is fitted into the notch 90 of the seat portion 40. By pulling out the pin 64, the rod 70 is allowed to advance, and the tension pulley 32 is engaged with the timing belt 24 as shown in FIG. By tightening the bolt 56, the tension adjustment mechanism 30
Is fixed to the cylinder block, but the protrusion 88
Since there is a slight tightening allowance between the notch 90 and the cut 90, the seal member 80 is not tightened when the bolt 56 is completely tightened.
The tubular portion 82 is pulled toward the flange portion 42a of the main body 42, and the pin insertion hole 93 on the seal member side and the pin insertion hole on the main body side are formed.
As shown in FIG. 3, the core is displaced from 66. as a result,
Foreign matter is prevented from entering from the outside through the pin hole 93. On the other hand, the seal between the main body 42 and the cylinder block insertion hole 52 is supported by the tubular portion 82 of the seal member 80,
The presence of lip 84 provides a good seal.
In addition, the seal with the protruding / retracting portion of the rod 70 is the bottom surface 95 of the tubular portion 82.
Secured by. Therefore, the oil filled in the main body for lubricating the piston 44 does not leak to the timing belt side.

〔effect〕

According to this invention, in the tension adjusting mechanism of the external insertion type, by providing a seal on the insertion portion of the main body, the rod and the pin and providing a gap between the seal and the seating surface thereof, the pop-out pin can be removed. Afterwards, when mounted on the mating mounting surface of the cylinder block, etc., the pin hole is misaligned between the seal member and the main body, so foreign matter can be prevented from entering the main body through the pin hole, and workability is improved. It is possible to improve the sealing property while maintaining the above.

[Brief description of drawings]

FIG. 1 is a sectional view of the tension adjusting mechanism of this invention. FIG. 2 is a top view of the tension adjusting mechanism for explaining the positional relationship with the cylinder block before assembly. FIG. 3 is a sectional view of the front end portion of the tension adjusting mechanism after the assembly is completed. FIG. 4 is a schematic perspective view showing the positional relationship between the tension adjusting mechanism and the mounting portion of the cylinder block during assembly. FIG. 5 is a view showing a configuration of a pulley belt drive system as seen from the front surface of the cylinder block in a completed assembled state. 10 …… Crank shaft, 12 …… Crank pulley, 22 …… Tension pulley, 24 …… Timing belt, 30 …… Tension adjusting mechanism (Tensioner), 40 …… Seat, 42 …… Main body, 44…
… Piston, 46 …… Rod, 48 …… Coil spring, 64 ……
Pop-out prevention pin, 66, 70, 93 ... pin hole, 80 ... sealing member, 82 ... tubular portion, 84 ... lip portion, 88 ... raised portion,
90 ... notch.

Claims (1)

[Scope of utility model registration request] 1. A tension belt urged by a pulley belt transmission system connecting a rotational force from a crank shaft to a driven portion such as a cam shaft and an elastic tension control mechanism for controlling the tension of the belt is a cylinder. The tension control mechanism is covered with a belt cover fixed to the front surface of the block from the outside, and the tension control mechanism cooperates with a main body that is inserted into the insertion hole of the cylinder block from the outside, and elastically retractable with respect to the main body. Including a tension member for applying tension to the belt, a detachable pop-out prevention pin that holds the tension member in a contracted position in the main body before mounting, an insertion hole for the pop-out prevention pin, and a sliding portion of the tension member. Elastic means for sealing the insertion part of the main body into the insertion hole of the cylinder block, the elastic means being formed as a bottomed cylindrical seal member, The seal member is mounted by sandwiching the opening-side end surface between the seating surface of the main body and the mating mounting seat surface, and the sliding portion of the tension member maintains a sealed state with respect to the bottom surface of the seal member. The slide-out prevention pin is inserted into the pin hole of the sliding portion of the tension member through the pin hole of the cylindrical portion of the seal member and the pin hole of the insertion portion before mounting, and the opening of the seal member Before the side end surface is attached to the mating side mounting seat surface, there is a gap between the side end surface and the opposing body seating surface, and when the body is attached to the mating side mounting seat surface by pulling out the pop-out prevention pin, A belt tensioning device, characterized in that the pin hole of the tubular portion and the pin hole of the insertion portion are displaced from each other by being deformed by the amount of the gap.