JP2010007813A - Tensioning device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tensioning device capable of increasing the elongation of a chain and the pressing force to the chain. <P>SOLUTION: The tensioning device comprises a tensioner arm 2 having an open hole 21a in a free end 21, a rotary piston unit 40 which is turnably supported by the open hole 21a in the free end 21, forms first and second chambers 22, 23 between the open hole 21a and itself, and has a bolt fitting hole 40a at the position offset from a center O of the open hole 21a, a fitting bolt 5 inserted in the bolt fitting hole 40a and screwed to a fixed wall 50, a first oil feed passage 5a formed in the fitting bolt 5, and a second oil feed passage 40c which is formed in the rotary piston unit 40 to introduce the hydraulic pressure from the first oil feed passage 5a into the first chamber 22. When introducing the hydraulic pressure into the first chamber 22, the rotary piston unit 40 is turned around the fitting bolt 5, and the free end 21 of the tensioner arm 2 is turned around the free end 20 to apply the pressure to a chain. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a tensioning device for generating tension in a chain, and more particularly to an improved structure for increasing a pressing force against a chain with an increase in chain elongation.

  As a tensioning device that generates tension in a chain, for example, as shown in FIG. 2. Description of the Related Art A tensioning device that includes a hydraulic tensioner that applies a pressing force to a tensioner is used. The hydraulic tensioner includes a housing, a plunger that is slidably supported in the housing, a spring that biases the plunger toward a side protruding from the housing, and a chamber formed between the plunger and the housing inside the housing. Has been.

  When the chain is slack during operation, the plunger protrudes toward the chain due to the elastic repulsive force of the spring, and at this time, oil is introduced into the chamber. Then, when the pressing force from the plunger to the chain by the resultant force of the hydraulic pressure in the chamber and the urging force of the spring balances the drag force acting on the plunger from the chain, the movement of the plunger stops.

In the above-described conventional tensioning device, when the plunger protrudes, the spring is stretched to reduce the amount of elastic deformation of the spring. For this reason, the biasing force by the spring is reduced. Therefore, when the chain is slack, the pressing force acting on the chain from the plunger is reduced. Further, in the above conventional apparatus, it is necessary to separately provide a hydraulic tensioner in addition to the tensioner arm, and the entire apparatus is enlarged.
Japanese Utility Model Publication No. 6-45141 (see FIG. 1)

  The present invention has been made in view of such conventional circumstances, and the problem to be solved by the present invention is to provide a small tensioning device capable of increasing the pressing force against the chain as the chain stretches. There is in point to do.

  The tensioning device according to the first aspect of the present invention has a chain sliding surface on which the chain slides, has a free end that can rotate around a support end supported by a fixed wall, and opens to the free end. A tensioner arm formed with a hole and a free end opening rotatably supported, and having an outer peripheral surface forming first and second chambers with the inner peripheral surface of the opening. A rotary piston portion having a support shaft mounting hole at a position offset from the center, a support shaft inserted into the support shaft mounting hole of the rotary piston portion and attached to a fixed wall around the tensioner arm, and the inside of the support shaft The first oil supply passage formed in the engine and supplied with hydraulic pressure from the engine, and the hydraulic pressure formed in the rotary piston portion and supplied to the first oil supply passage are introduced into the first chamber. And a second oil supply passage. When the hydraulic pressure is introduced into the first chamber, the rotary piston rotates around the support shaft, so that the free end of the tensioner arm rotates around the support end toward the chain, and the pressing force is applied to the chain. It comes to work.

  According to the first aspect of the present invention, when slack occurs in the chain during operation, hydraulic pressure is introduced from the first oil supply passage into the first chamber through the second oil supply passage. Then, the rotary piston portion rotates around the support shaft. At this time, the support shaft mounting hole into which the support shaft is inserted is offset from the center of the opening at the free end of the tensioner arm (that is, eccentrically provided), so that the rotary piston portion rotates around the support shaft. , The rotary piston portion protrudes toward the chain, thereby moving the tensioner arm free end toward the chain via the opening of the tensioner arm free end. As a result, the pushing amount of the free end of the tensioner arm toward the chain increases and a pressing force acts on the chain.

  In this case, the pressing force acting on the chain is not based on the elastic repulsive force of the spring but based on the hydraulic pressure acting on the first chamber. Further, as the rotary piston portion rotates, the rotary piston portion is free from the tensioner arm. Since the distance between the line of force acting on the end opening and the center of the bolt mounting hole is gradually shortened (see FIGS. 2A and 2B), from the balance of the moment of force around the center of the spindle mounting hole, The force that the rotary piston part exerts on the opening of the free end of the tensioner arm (and therefore the pressing force that acts on the chain) increases as the amount of pushing of the rotary piston part toward the chain increases as the rotary piston part rotates. become.

  In addition, in this case, a hydraulic tensioner is not provided separately from the tensioner arm, but an opening is formed in the free end of the tensioner arm, and the rotary piston portion and the first and second chambers are provided in the opening. As a result, the entire apparatus can be reduced in size.

  According to a second aspect of the present invention, in the first aspect, the oil in the reverse direction is allowed between the first oil supply passage and the second oil supply passage while allowing the oil to flow toward the first chamber. A chuck valve is provided to prevent the flow.

  In this case, when the hydraulic pressure is introduced into the first chamber, the oil is introduced from the first and second oil supply passages through the check valve. Further, when excessive pressing force acts on the free end of the tensioner arm at the time of resonance of the chain, the oil outflow from the first chamber is restricted by the check valve. Thus, a rapid decrease in the volume of the chamber can be prevented, and a sudden retraction of the free end of the tensioner arm can be prevented.

  According to a third aspect of the present invention, in the first aspect, ratchet teeth are formed on the inner peripheral surface of the opening at the free end of the tensioner arm, and the rotary piston portion is urged to engage with the ratchet teeth. The ratchet mechanism, which is composed of ratchet teeth and poles, allows rotation of the tensioner arm free end toward the chain and restricts rotation toward the side away from the chain. Yes.

  In this case, when the slack of the chain occurs and the free end of the tensioner arm moves toward the chain, the ratchet mechanism is idled and the rotation of the free end of the tensioner toward the chain is allowed. Further, when the tensioner arm free end is pushed in by the pressing load from the chain, the ratchet mechanism is engaged, and the rotation of the tensioner free end away from the chain is restricted, whereby the volume of the first chamber is restricted. Of the tensioner arm can be prevented from abruptly retreating.

  In the invention of claim 4, in claim 1, the support end of the tensioner arm is slidably supported on a fixed wall around the tensioner arm. According to a fifth aspect of the present invention, in the first aspect, a long hole is formed at the support end of the tensioner arm, and a pin through which the long hole is inserted is fixed to the fixed wall.

  When the rotary piston part rotates around the support shaft, the rotary piston part moves slightly toward the support end of the tensioner arm or away from the support end. As a result, the support end of the tensioner arm moves a little. However, in this case, in the invention of claim 4, the support end is slidably supported on the fixed wall, and in the invention of claim 5, the pin fixed to the fixed wall is inserted through the long hole of the support end. These structures can absorb the amount of movement of the tensioner arm support end.

  According to a sixth aspect of the present invention, in the first aspect, the second chamber is open to the atmosphere.

  In this case, when the hydraulic pressure is introduced into the first chamber, the volume of the first chamber increases, and as a result, the volume of the second chamber decreases and is compressed. At this time, the volume decreases. Excessive oil is discharged from the second chamber into the atmosphere.

  As described above, according to the tensioning device of the present invention, an opening is formed in the free end of the tensioner arm, the rotary piston portion is rotatably provided in the opening, and the first and second chambers are provided. Forming a support shaft mounting hole in the rotary piston portion at a position offset from the center of the opening, inserting the support shaft into the support shaft insertion hole, attaching it to the surrounding fixed wall, and further hydraulically supplying to the first chamber Since the first and second oil supply passages are provided for introducing the shaft, when the chain is extended, the rotary piston portion rotates around the support shaft while rotating in the opening of the free end of the tensioner arm. The rotary piston part protrudes toward the chain, and the amount of pushing the tensioner arm free end toward the chain increases.

  In this case, the pressing force acting on the chain is not based on the elastic repulsive force of the spring but based on the hydraulic pressure acting on the first chamber. Further, as the rotary piston portion rotates, the rotary piston portion is free from the tensioner arm. Since the distance between the line of force acting on the opening of the end and the center of the support shaft mounting hole is gradually shortened, the force that the rotary piston exerts on the opening of the free end of the tensioner arm (and hence the pressing force exerted on the chain) is As the rotary piston portion rotates, the amount of push of the rotary piston portion toward the chain increases.

  In addition, in this case, a hydraulic tensioner is not provided separately from the tensioner arm, but an opening is formed in the free end of the tensioner arm, and the rotary piston portion and the first and second chambers are provided in the opening. Since it did in this way, the whole apparatus can be reduced in size.

  1 to 3 are diagrams for explaining a tensioning device according to an embodiment of the present invention. FIG. 1 is a schematic front view of a timing chain system employing the tensioning device according to the present embodiment. 1 is an enlarged view of the free end of the tensioner arm of FIG. 1, FIG. 2B is a view showing a state where the free end of the tensioner arm of FIG. 2A is moved to the chain side, and FIG. 3 is a cross-sectional view taken along line III-III of FIG.

  As shown in FIG. 1, the timing chain system 100 is wound around a crank sprocket 101 attached to an engine crankshaft, cam sprockets 102 and 103 attached to a camshaft, and these sprockets 101, 102 and 103. Timing chain 104. In addition, the arrow in a figure has shown the rotation direction of the sprocket.

  The tensioning device 1 is provided on the slack side span of the timing chain 104. The tensioning device 1 includes a support end 20 that is slidably supported on a fixed wall 50 such as an engine cylinder block, a free end 21 that is rotatable about the support end 20, a support end 20 and a free end. The tensioner arm 2 is disposed between the ends 21 and has a chain sliding surface 2a on which the chain 104 slides.

  As shown in FIGS. 2A and 3, a circular opening 21 a is formed in the free end 21 of the tensioner arm 2. A rotary piston portion 40 is rotatably supported in the opening 21a. The rotary piston portion 40 has an outer peripheral surface that forms the first and second chambers 22 and 23 with the inner peripheral surface of the opening 21a. The first and second chambers 22 and 23 are separated from each other via two pins 30 and 31 that are implanted at the edge of the opening 21 a of the tensioner arm 2. The outer peripheral surface of the rotary piston portion 40 is always in contact with the outer peripheral surfaces of the pins 30 and 31, and the outer peripheral surface slides on the outer peripheral surfaces of the pins 30 and 31 when the rotary piston portion 40 rotates.

Rotary piston part 40 has a bolt insertion hole (shaft mounting hole) 40a in a position offset from the center O of the opening 21a (see center O _b). A mounting bolt (support shaft) 5 is inserted into the bolt insertion hole 40a. The threaded portion of the mounting bolt 5 is screwed to a fixed wall (for example, a cylinder block) 50 around the tensioner arm 2. The rotary piston part 40 is rotatable around the mounting bolt 5.

  A first oil supply passage 5 a to which hydraulic pressure from the engine is supplied is formed inside the mounting bolt 5. The first oil supply passage 5a includes a passage extending in the axial direction inside the mounting bolt 5 and a passage extending in a direction perpendicular to the passage. The rotary piston portion 40 is formed with an oil supply passage 40b that communicates with the first oil supply passage 5a. The rotary piston portion 40 is further formed with a second oil supply passage 40c communicating with the oil supply passage 40b via the check valve 41. The terminal end of the second oil supply passage 40 c is open to the first chamber 22. The check valve 41 includes a ball and a valve spring that urges the ball toward the valve seat side in the lower part of FIG. 3 and allows oil to flow from the oil supply passage 40b to the second oil supply passage 40c. However, it acts to block the oil flow in the opposite direction.

  A ratchet mechanism 6 is provided at the free end 21 of the tensioner arm 2. The ratchet mechanism 6 includes a plurality of ratchet teeth 60 formed on the inner peripheral surface of the opening 21 a and a pole 61 provided on the rotary piston portion 40 and capable of engaging with the ratchet teeth 60. The pole 61 is rotatably provided around the pin 62 and is biased toward the ratchet teeth 60 by a biasing member (not shown). The ratchet mechanism 6 permits the rotation of the free end 21 of the tensioner arm 2 toward the chain (the direction in which the rotary piston portion 40 rotates clockwise in FIG. 2A) and the side away from the chain (the rotary in FIG. 2). The piston portion 40 is configured to be restricted from rotating in the counterclockwise direction).

  An end cap 7 is attached to the end face of the free end 21 of the tensioner arm 2 (not shown in FIG. 2A). The end cap 7 is fixed to the end surface of the free end 21 by the mounting bolt 5. The second chamber 23 is open to the atmosphere through a through hole 6 a formed in the end cap 7.

Next, the function and effect of this embodiment will be described.
As shown in FIG. 1 and FIG. 2A, the rotary piston 40 is freed of the tensioner arm 2 via the pin 30 by the hydraulic pressure supplied to the first chamber 22 in a state before the timing chain 104 is extended due to wear. the pressing force to be applied to the end 21 and F _2, the distance between the center O _b line of action of the pressing force F ₂ and the mounting bolts 5 and L _2. Further, the hydraulic pressure acting in the first chamber 22, a moment for rotating the rotary piston part 40 in a clockwise direction in FIG. 2A When M _1, the force with respect to the center O _b of the mounting bolt 5 for rotary piston part 40 The following equation holds depending on the balance of moments.
M ₁ = −F ₂ · L ₂
Here, -F ₂ is a reaction force of the pressing force F _2, a force acting in the opposite direction to the rotary piston part 40.
This was solved for _{F 2,}
F ₂ = −M ₁ / L ₂ (1)

  Next, when the timing chain 104 extends due to wear, the hydraulic pressure from the engine is supplied to the first chamber 22 via the first oil supply passage 5a, the oil supply passage 40b, the check valve 41, and the second oil supply passage 40c. To be supplied.

  Then, the rotary piston portion 40 rotates around the mounting bolt 5 in the clockwise direction in FIG. 2A, the volume of the first chamber 22 increases (see FIG. 2B), and the free end 21 of the tensioner arm 2 becomes the support end. Rotate around 20. At this time, the rotary piston part 40 protrudes to the chain side (the right side in the figure), and the pushing amount of the free end 21 of the tensioner arm 2 toward the chain side increases. Further, when the rotary piston part 40 rotates, the ratchet mechanism 6 idles and allows the rotary piston part 40 to rotate. When the free end 21 of the tensioner arm 2 rotates around the support end 20, the free end 21 moves a little in the vertical direction in FIG. 1, but this movement amount is such that the support end 20 is above the fixed wall 50. Is absorbed by sliding.

In the state shown in FIG. 2B, the pressing force applied to the free end 21 of the tensioner arm 2 via the pin 30 by the hydraulic pressure supplied to the first chamber 22 is F ₂ ′, and the pressing force F _'the distance between the center O _b line of action and the mounting bolts 5 of L _{2' 2} to. Further, assuming that the moment for rotating the rotary piston portion 40 in the clockwise direction in FIG. 2A by the hydraulic pressure acting in the first chamber 22 is M ₁ ′, the force related to the center O _b of the mounting bolt 5 with respect to the rotary piston portion 40. Depending on the moment balance, the following equation holds.
M ₁ ′ = −F ₂ ′ · L ₂ ′
Here, −F ₂ ′ is a reaction force of the pressing force F ₂ ′ and is a force that acts on the rotary piston portion 40 in the opposite direction.
Solve this for F ₂ '
F ₂ ′ = −M ₁ ′ / L ₂ ′ = −M ₁ / L ₂ ′ [∵ M ₁ = M ₁ ′] (2)
Here, when the right sides of the expressions (1) and (2) are compared, since L ₂ ′ <L ₂ , F ₂ ′> F ₂
It becomes.

  As described above, the pressing force exerted on the chain side by the free end 21 of the tensioner arm 2 increases as the amount of pushing of the free end 21 of the tensioner arm 2 toward the chain increases with the rotation of the rotary piston portion 40. It will be.

  By the way, in the initial operation state in which the chain is not worn, the pressing force against the chain may not be large. If it is too large, the chain will be worn or the wear of the chain sliding surface of the tensioner arm will be accelerated. .

  In this embodiment, as described above, when the chain is worn, the pressing force against the chain can be increased by rotating the rotary piston portion and projecting toward the chain, so the chain is not worn. During the initial operation, the hydraulic pressure of the hydraulic tensioner can be lowered to reduce the pressing force against the chain. This can reduce chain wear during initial operation and improve engine fuel efficiency.

  In addition, in this case, a hydraulic tensioner is not provided separately from the tensioner arm, but an opening is formed in the free end of the tensioner arm, and the rotary piston portion and the first and second chambers are provided in the opening. Since it did in this way, the whole apparatus can be reduced in size.

  In the above-described embodiment, the example in which the support end 20 of the tensioner arm 2 is slidably supported on the fixed wall 50 is shown, but the application of the present invention is not limited to this. FIG. 4 is a schematic front view of a tensioning device according to another embodiment of the present invention, in which the same reference numerals as those in the above-described embodiment indicate the same or corresponding parts.

  As shown in FIG. 4, a long hole 20a is formed in the support end 20 of the tensioner arm 2, and the support end 20 is fixed to a fixed wall such as a cylinder block via a pin 25 inserted into the long hole 20a. It is pivotally supported by.

  In this case, the vertical movement of the free end 21 when the free end 21 of the tensioner arm 2 rotates around the support end 20 can be absorbed by the long hole 20 a of the support end 20.

1 is a schematic front view of a timing chain system employing a tensioning device according to an embodiment of the present invention. It is an enlarged view of the tensioner arm free end of FIG. It is a figure which shows the state which the tensioner arm free end (FIG. 2A) moved to the chain side. It is the III-III sectional view taken on the line of FIG. 2A. FIG. 6 is a schematic front view of a tensioning device according to another embodiment of the present invention.

Explanation of symbols

1: Tensioning device

2: Tensioner arm 20: Support end 21: Free end 21a: Opening hole 22: First chamber 23: Second chamber

5: Mounting bolt 5a: First oil supply passage

40: Rotary piston portion 40a: Bolt mounting hole 40c: Second oil supply passage

50: Fixed wall

104: Chain

O: Open hole center

Claims (6)

A tensioning device,
A tensioner arm having a chain sliding surface on which the chain slides, a free end rotatable around a support end supported by a fixed wall, and an opening formed in the free end;
The free end is rotatably supported by the opening, has an outer peripheral surface that forms first and second chambers with the inner peripheral surface of the opening, and is offset from the center of the opening A rotary piston portion having a spindle mounting hole at a position;
A spindle that is inserted into the spindle mounting hole of the rotary piston portion and is attached to a fixed wall around the tensioner arm;
A first oil supply passage that is formed inside the support shaft and is supplied with hydraulic pressure from the engine, and a hydraulic pressure that is formed in the rotary piston portion and supplied to the first oil supply passage. A second oil supply passage for introducing into the chamber,
When the hydraulic pressure is introduced into the first chamber, the rotary piston portion rotates around the support shaft, so that the free end of the tensioner arm rotates around the support end toward the chain. The pressing force is applied to the chain.
A tensioning device characterized by that. In claim 1,
A chuck valve is provided between the first oil supply passage and the second oil supply passage to prevent the oil flow in the reverse direction while allowing the oil to flow toward the first chamber. Being
A tensioning device characterized by that. In claim 1,
Ratchet teeth are formed on the inner peripheral surface of the opening at the free end of the tensioner arm, and the rotary piston portion is provided with a pole urged to engage with the ratchet teeth. The ratchet mechanism constituted by the ratchet teeth and the pawls allows the tensioner arm to rotate to the side of the free end toward the chain and restricts the rotation to the side away from the chain. ,
A tensioning device characterized by that. In claim 1,
The support end of the tensioner arm is slidably supported on a fixed wall around the tensioner arm;
A tensioning device characterized by that. In claim 1,
A long hole is formed in the support end of the tensioner arm, and a pin that passes through the long hole is fixed to the fixed wall.
A tensioning device characterized by that. In claim 1,
The second chamber is open to the atmosphere;
A tensioning device characterized by that.

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