KR19990022765A - Tension Device for Drive Chain - Google Patents

Abstract

An internal combustion engine, for example a tension device for a chain or belt of a camshaft drive shaft, comprises a cylindrical tension device housing 2 which is loaded with a piston 1 by means of a built-in compression spring 13. The device housing and the piston are adapted to be axially movable relative to one another. The element movable relative to the stationary element in the chain tension direction is enclosed by a first stop ring that restricts movement backwards. According to the present invention, the first stop ring is formed with a retaining clip 15, in which the arms are engaged in the locking groove 16 of the tension device housing 2 by applying radial compressive stress, so as to be accommodated when the tension device housing moves. It can be adapted to support axially with respect to the stop face of the housing 3.

Description

Tension Device for Drive Chain

Such tension device is mounted on the loose part of the drive chain, and the compression spring transmits the tension force to the loose side of the control gear. The average tensile force generated in normal operation is smaller on the actuation or tension side so that the compression spring operates according to the smaller tensile force. The piston and tensioner housing assembly acting on the chain provides the required chain tension by being stretched by the elastic force of the compression spring.

The piston and the assembly may be composed of an oil tank, a high pressure chamber and a hydraulic damping device having an intermediate non-return valve. The piston and tensioner housing assembly is operated by the pulsating force from the drive chain, and the pressure oil contained in the space inside the assembly is formed between the piston and the tensioner housing so as to assist the action of the compression spring with its pressure. It can be discharged from the high pressure chamber through the leaking gap.

In special cases, if the oil in the high pressure chamber has not reached the set pressure or is partially filled so that the pressure in the high pressure chamber is only partially or completely at the set pressure, the required chain tension can be established by the tensioning device. There will be no. The damping effect is inadequate and the pulsating force from the drive chain may suddenly shrink the tension device. An example of such a special case is when a car is parked on a hill inclined in the driving direction with the forward gear engaged in the car engine so that the engine tends to rotate in the reverse direction by the car's own weight. This creates tension in the loose parts of the chain. In such a case, unless a stop ring is provided that restricts rearward movement, the large chain tension forces the high pressure generator's piston and tensioner housing assembly to retract completely after the engine is stopped. When the engine is started again and the loose part of the chain is suddenly relaxed, the chain tension is insufficient, which may cause the piston to retract significantly and cause uncontrolled knocking of the chain. This may cause the chain to drive by driving the teeth of the drive pinion of the camshaft drive, which may result in improper valve gear timing, for example damaging the engine since the valve disc will strike the piston upper surface.

Tension devices of the type cited above are known from DE-OS 36 36 918. The piston, which may extend out of the tensioner housing fixed in the tensioner, acts on the chain in a direction that causes the chain to tension. When the chain tension device is activated, the first stop ring is fitted into the first locking groove of the tension device housing. This position is at the front of the chain tension range. The stop jaws of the piston come into contact with the first stop ring when the pressure in the high pressure chamber is not sufficient to cause the piston to be stopped by the load. This prevents the piston from moving backward into the tensioner housing. The stop ring therefore acts as a safeguard against the retraction stroke or the piston being locked. Stop rings of this type are made of wire, which should have a minimum wire diameter, taking into account both the rigidity of the part and the dimensional tolerances. The stop ring of this minimum diameter wire should have a slight change in ring diameter while the ring is in operation and have a significantly increased rigidity while the wire diameter remains the same when the stop ring diameter is reduced.

The present invention relates to, for example, a tensioning device for a chain or belt for camshaft driving of an internal combustion engine, comprising a piston to which a force of a compression spring mounted in an inner space is applied, and which is movable axially with respect to the piston. And a cylindrical tensioning device housing and a movable element with respect to the anchoring element in the chain tension direction surrounded by the first stop ring restricting movement to the rear.

1 is a side view of the tension device in the chain tension direction.

FIG. 2 is a bottom view of the housing of the tension device by line II of FIG. 1.

3 is a longitudinal cross-sectional view of the retracted housing of the tension device;

4 is a longitudinal sectional view of the tension device by line IV of FIG. 3 in a state where the tension device is extended;

5 is a longitudinal cross-sectional view of a state in which the tension device of the modification is retracted.

6 is a longitudinal cross-sectional view of a tension device of the modification according to line VI in FIG. 5 with the tension device housing extended;

It is an object of the present invention to provide a tension device having a smaller overall size than a conventional chain tension device, requiring a small installation space.

In order to achieve the object of the present invention, the first stop ring has two arms which are radially pressed into the locking groove of the movable element and are axially supported against the fixed stop member when the movable element is moved. It consists of a U-shaped retaining clip with an arm. The use of retaining clips in the annular stop ring as a safety measure to prevent the piston from immersing deeply into one side of the cylinder does not reduce the wire diameter even when the locking groove has a reduced diameter, The necessary rigidity can be obtained. The rigidity of the first stop ring configured as the retaining clip is not changed so that the elastic force of the compression ring can be kept the same, thereby avoiding a large change in the undesirable spring elastic force acting on the chain to be tensioned.

The tensioner housing as a movable element can be guided in a cylindrical bore of a fixed housing, with a fixed stop ring installed in the housing, while a second stop ring is radiused in the groove on the inner circumferential surface of the housing. It can be configured to be inserted biased in the direction. However, the movable element may be a piston guided to a tensioner housing inserted into a cylindrical bore of a fixed receiving housing.

A plurality of locking grooves in the form of grooves on the outer circumferential surface to accommodate the retaining clip may be formed in an axially spaced relationship to the tension device housing. In a position where the tensioner housing is fully inserted into the receiving housing, a transport safety loop can be mounted between the retaining clip and the second stop ring. When the tension device is mounted on the engine, the transport safety ring is removed and the tension device takes the operating position. The retaining clip constitutes a mechanical safety device that restricts the tension device housing from retracting and locking in the receiving housing when the high pressure chamber is emptied and the force exerted by the chain becomes large. Furthermore, the retaining clip also acts as a mechanical safety device that does not detach by holding together components consisting of a piston, a tensioner housing and a receiving housing.

The tensioner housing and the piston can additionally be held together by an outwardly biased retaining ring, the retaining ring projecting radially and partially inserted into the annular groove of the piston to the inclined surface of the tensioner housing around it. Supported axially. In this case, the diameter of the bottom portion of the circumferential groove of the piston may be slightly smaller than the diameter at which the fixing ring can be completely accommodated in the groove.

The piston and tensioner housing can be made of steel, while the receiving housing can be made of aluminum alloy.

The invention is explained in more detail with reference to the embodiments illustrated in the drawings.

The tension device of the invention shown in FIGS. 1 to 4 comprises a piston 1, a tension device housing 2 and a receiving housing 3. The piston has a fastener with one end inserted into the tensioner housing 2, the tensioner housing 2 being cylindrical and comprising a movable element. The piston 1 is held by a fixing element, denoted by a fixing ring 4. The fixing ring 4 is arranged to partially protrude radially in the groove 5 on the outer circumferential surface of the piston 1. It can be brought into contact with the ramp 1 of the piston 1 and the tensioner housing 2 to prevent further relative movement. The retaining ring 4 is fully pressed radially into the outer circumferential groove 5 of the piston 1, and then elastically restored radially as the housing 2 is pushed in.

A non-return valve 7 for separating the high pressure chamber 8 of the tension device housing 2 from the oil reservoir 9 of the piston 1 is arranged in the communication space between the piston 1 and the tension device housing. The piston 1 made of a cylindrical body is supported on the bottom portion with the cylindrical bore 10 of the accommodating housing 3 at an end far from the non-return valve 7, and the piston 1 is connected to the accommodating housing 3. It is stopped as well. The pressurized oil is supplied to the oil reservoir 9 through the oil inlet 11 and the oil transfer groove 12.

The compression spring 13 provided in the tensioner housing 2 has its one end supported by the piston 1 and the other end fixed to the bottom of the tensioner housing 2. The compression spring 13 acts to advance the tensioner housing 2 from the housing 3 away from the piston in the chain extending direction, while the pulsating force from the chain is applied to the tensioner housing at the piston 1. 2) It acts in the direction of retracting the tension device housing 2 in the direction opposite to the action of the compression spring 13 inward. The non-return valve 7 provided with a ball as a sealing means is opened at the time of the extension movement of the tension device housing 2, and is closed at the time of the return operation.

The pressurized oil contained in the high pressure chamber 8 is discharged from the tension device housing 2 through the leakage gap 14 between the piston 1 and the tension device housing 2 when the tension device housing 2 is retracted. The pressurized discharge of the pressurized oil from the high pressure chamber 8 of the tension device housing 2 thus produces a damping effect on the tensioned chain, which carries a large fluid friction and transmits a pulsating force to the tension device housing 2.

The tension device housing 2 is gripped by two arms, a U-shaped retaining clip 15, which retains a plurality of axially spaced locking grooves formed in the tension device housing 2. It acts as a first stop ring disposed at. The tension device housing 2 comprises a first locking groove 16, a second locking groove 17, and a third locking groove 18 in order from the bottom in the direction of the piston 1. The retaining clip 15 may be coupled to either the second locking groove 17 or the third locking groove 18, in which case the tensioner housing 2 as contacted with respect to the inclined stop surface 19. ) No longer moves inward into the receiving housing (3).

In FIG. 3, the tension device is in a transport position in which the tension device housing 2 is fully retracted into the receiving housing 3, in which case the outer peripheral surface groove of the tension device housing 2 in the bottom region of the tension device housing 2. It is held by a safety transport circlip 20 coupled to 21. The first locking groove 16 prevents the retaining clip 15 from locking in the peripheral groove 21 necessary for the transportation of the tensioning device. The safe transport circlip 20 supports in the axial direction with respect to the second stop ring 22 held in the groove around the inner side of the accommodating housing 3. As long as the safety transport circlip 20 is arranged in the groove 21 of the tension device housing 2 at one point of the at least one outer circumferential surface, the tension device housing 2 cannot be released from the accommodation housing 3.

The tension device is assembled as follows for transportation. That is, after assembling the piston 1, the non-return valve 7, the compression spring 13 and the tension device housing 2, the retaining clip 15 is pushed into the tension device housing 2 in the axial direction. And is coupled to the first locking groove 16. The pre-prepared piston and tensioner housing assembly is then inserted into the cylindrical bore 10 of the receiving housing 3 and the tensioner housing is then fully press-fitted into the receiving housing 3 in the direction opposite to the action of the compression spring 13. do. The second stop ring 22 can be inserted into a groove provided in the accommodating housing 3. The safety transport circlip 20 is then inserted into the receiving housing 3 in the direction opposite to the axial direction and coupled to the peripheral groove 21 of the tensioner housing 2. The tensioner housing 2 no longer moves away from the receiving housing 3 by the action of the compression spring 13, which is secured by a safe transport circlip 20 which is supported against the second stop ring 22. Because it interferes with it. The accommodating housing can then be moved and screwed into the engine provided with two screw holes 23.

The tension device shown in Figs. 1 to 4 operates as follows. After the tension device is screwed into the engine, the tension device is operated by removing the safety transport circlip 20 for safe transport of the tension device. When the tension device housing 2 is released from the cylindrical bore 10 of the receiving housing 3 by the action of the compression spring 13, it is disposed in the first locking groove 16 of the tension device housing 2 to lift the tension device. The retaining clip 15, which is biased towards it, is retained by the tensioner housing 2 until it is arranged with respect to the second stop ring 22. As shown in FIG. Such protrusion may occur, for example, as the chain wears and stretches. As the tension device housing 2 moves further outward, the retaining clip 15 is pushed out of the tension device housing 2 and fitted into the next locking groove 17. When the engine is turned off from the hill, for example, the tensioner housing 2 is pressed into the receiving housing 3 in the opposite direction to the force of the compression spring 13 by the large chain force on the loose side so that the retaining clip 15 is retained. Is located on the inclined stop surface 19 of the accommodating housing 3, thereby preventing the tension device housing 2 from further retreating. In this way, the timing chain is prevented from jumping off the teeth of the drive pinion upon engine reignition. In addition, due to the limitation of the retreat stroke, less oil is leaked from the high pressure chamber 8, so that the amount of oil that needs to be recharged in the high pressure chamber 8 when the engine is restarted is required, which prevents noise generation due to lack of damping. Because it is important.

At the same time, the tension device ensures minimization of the retraction stroke of the tension device housing 2, which is necessary for the provision of a damping stroke and for the compensation of the eccentricity and thermal expansion of the chain pulley. This retraction stroke can be seen in FIG. 3 as the distance between the retaining clip 15 and the second stop ring 22.

In the variant of the invention shown in FIGS. 5 and 6, the piston 24 is guided as a movable element in the tensioner housing 25 made of steel constituting the stationary element. The valve seat disk 26 is welded to one end of the tensioner housing 25. The tensioner housing 25 together with the valve seat disk 26 is inserted into a receiving housing 27 made of aluminum. At one end of the tensioner housing 25 remote from the valve seat disk 26, the receiving housing 27 comprises a projection 28 at least at one outer circumferential surface, by means of which the tensioner housing 25 is connected to the housing. At 27) it is not possible to rotate. The valve seat disc 26 is supported on the bottom of the receiving housing 27.

The non-return valve 29 disposed in the tension device housing 25 seals the inner space forming the high pressure chamber 30 for the oil pressure with respect to the oil supply pipe. The oil supply is made through the oil inlet 31, the oil delivery groove 32 of the receiving housing 27 and the center hole of the valve seat disk 26.

In the tension device housing 25, the compression spring 33 is arranged in the bore of the piston 24 constituting the high pressure chamber 30, one end of the compression spring 33 is supported by the piston 24 and the other end is tension device. It is supported by the valve seat disk 26 of the housing 25. The compression spring 33 protrudes the piston 24 from the tension device housing 25 in the chain tension direction, and the pulsating force from the chain causes the piston 24 to move against the action of the compression spring 33. Retreat to (25). The non-return valve 29 with the ball as the seal means can be opened while the piston 24 is protruding and closed during retraction. The pressurized oil contained in the high pressure chamber 30 is discharged from the high pressure chamber 30 and flows through the leak gap 34 between the piston 24 and the tension device housing 25 during the retraction stroke of the piston. The pressurized oil discharge from the high pressure chamber is accompanied by a high pressure friction to damp the pulsating force transmitted from the chain to be tensioned to the piston 24.

The piston 24 is enclosed by a retaining clip 35 in which two arms are U-shaped, the retaining clip 35 having a plurality of axially spaced locking grooves formed in the piston 24. It acts as a stop ring. Looking in the direction of the tensioner housing 25 from the outer end face of the piston 24, the piston 24 is continuously the first locking groove 36, the second locking groove 37 and the third locking groove 38. Include them. The retaining clip 35 is engaged in the first locking groove 35 in the state where the piston is advanced and fully protruded. The retaining clip 35 can be engaged with either of the locking grooves 37, 38 while the piston 24 is advancing, and furthermore the inclined stop as the piston 24 moves into the tensioner housing 25. The contact with the face 39 prevents the piston from moving into the receiving housing.

In FIG. 5, the tensioning device is a carriage in which the piston 24 held by the safety transport circlip 40 coupled to the groove 41 of the outer circumference at the outer end of the piston 24 is completely retracted into the receiving housing 27. It is shown by location. The locking groove 36 serves to prevent the retaining clip 35 from being locked in the outer circumferential surface groove 41 required for the movement of the tension device. The safety transport circlip 40 bears axially with respect to the second stop ring 42 held in the groove of the inner side of the receiving housing 27. As long as the safety transport circlip 40 is disposed in the outer circumferential groove 41 of the piston 24 at at least one point of the outer circumferential surface, the piston 24 protrudes from the tension device housing 25 and the accommodating housing 27. It becomes impossible. Two screw holes 43 are provided in the accommodating housing 27 to fix the engine's tensioning device to the position of use. The operation method and assembly for transportation of the tension device modified according to FIGS. 5 and 6 are the same as the operation method and assembly of the tension device of FIGS. 1 to 4 described above.

The present invention provides a tension device that can be prevented from being locked by mechanical means and the outer diameter of the housing can be very small, for example 14 mm or less. Such a tension device only requires a small space. This tension device is simple in structure and economic in manufacturing cost. Small force is required for the operation of the locking device. The tension device of the present invention comprises a simple safety device in the form of a safety transport circlip 20, 40 to lock a moving element such as the tensioner housing 2 or the piston 24 for mounting to the engine.

The retaining clips 15 and retaining clips 35 of the tensioning device are made by bending spring steel in a U-shape to apply a compressive stress so that they are always relative to the outer circumferential surface of the moving device such as the tensioner housing 2 or the piston 24. Supported. In the tension device shown in FIG. 5, the piston 24 is unlocked by pulling the safety transport circlip 40 and is the result of the spring force of the compression spring 33 and the engine oil pressure acting on the high pressure chamber 30. The piston 24 is projected from the tension device housing 25 in the chain tension direction. The compressive stress causes the retaining clip 35 to be loaded by the piston 24 until it is supported against the second stop ring 42. As the piston 24 protrudes further, the retaining clip 35 slides along the piston 24 and the chain remains stretched and snaps into the next locking groove 37. When the engine is stopped, the hydraulic pressure of the engine is no longer actuated so that the piston 24 can no longer be held against the pressure acting on the end from the chain, and the piston 24 retracts into the tensioner housing 25. do. During this retreat, the pressure oil of the high pressure chamber 30 is discharged through the leak gap 34.

This retraction of the piston 24 is stopped when the retaining clip 35 is supported against the inclined stop face 39 of the tensioner housing 25 (see FIG. 6). This prevents the chain from jumping off the chain pulley of the control gear and the chain rattle when the engine is reignitioned. At the same time a minimum return stroke of the piston 24 in the tensioning device is ensured and is necessary to provide a damping stroke and to compensate for thermal expansion and eccentricity of the chain pulleys.

Claims (10)

A compression spring is disposed therein, the piston being mounted to move the member relative to the cylindrical tension device housing which is axially movable with each other, and the element fixed in the chain tension direction wrapped by the first stop ring restricting the rearward movement. In a tension device for a belt or chain of an internal combustion engine for driving a camshaft, the first stop ring is adapted to radially exert a compressive stress in the locking grooves 16 to 18, 36 to 38 of the movable element. A tensioning device, characterized in that it is configured as a retaining retaining clip (15,35), and is adapted to axially support a fixed stop ring upon movement of the movable element. 2. The tension device housing (2) according to claim 1, wherein the tension device housing (2) is made of movable elements and is guided in a cylindrical bore (10) of a fixed housing (3), wherein the fixed stop ring is mounted to the housing (3). And a two-stop ring (22), the tension device being inserted into a groove of the inner surface of the housing housing (3) with radial compressive stress applied thereto. 3. The tension device according to claim 2, wherein the plurality of locking grooves (16, 17, 18) in the form of grooves on the outer surface for retaining the retaining clip (15) are arranged axially spaced apart in the tension device housing (2). . 3. The safety transport circlip 20 in accordance with claim 2, in the fully inserted position of the tensioner housing 2 of the accommodating housing 3, can be mounted in the accommodating housing 3 and the outer peripheral surface of the tensioner housing 2 Tension device is inserted into the groove (21). 5. The tension device according to claim 4, wherein the safety clip circlip (20) is arranged between the retaining clip (15) and the second stop ring (22). 3. The tension device housing (2) and the piston (1) according to claim 2 protrude radially in part into the outer circumferential groove (5) of the piston, and with respect to the ramp (6) surrounding the tension device housing (2). And a tensioning device held together by an outwardly biased retaining ring (4) adapted to be supported in a direction. The bottom diameter of the outer circumferential groove (5) of the piston (1) is slightly smaller than the diameter of the fixed ring (4), and the tension is such that the holding ring (4) is completely received in the outer circumferential groove (5). Device. 2. The tension device according to claim 1, wherein the piston (1) and the tension device housing (2) are made of steel, and the receiving housing (3) is made of aluminum alloy. The tensioner housing (2) according to claim 1, wherein the tensioner housing (2) is made of a movable element and guided in a cylindrical bore (10) of a fixed housing (3), the fixed stopper being disposed on the housing (3). A tension device, consisting of a second stop ring (22) and press-fitted into a cylindrical bore (10) of a receiving housing (3). 4. The piston (24) according to claim 1, wherein the piston (24) consists of a movable element guided in the tensioner housing (25) and inserted into a cylindrical bore of the receiving housing (27), with a fixed stop face disposed in the receiving housing (27). And a second stop ring (42) inserted into the groove on the inner circumferential surface of the accommodating housing (27) by radial compression.