JP3750812B2 - Chain tensioning device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a chain tension applying device that is used to apply an appropriate tension to a transmission chain that is hung inside a vehicle engine, and in particular, rotates between a crankshaft side sprocket and a camshaft side sprocket. This is called a chain tensioner used for a transmission timing chain.
[0002]
[Prior art]
As shown in FIGS. 11 to 13, the conventional chain tension applying device 500 includes a plunger 520 that protrudes forward and backward toward a traveling chain and a plunger sliding hole 511 into which the plunger 520 is inserted. The main body 510, a projecting biasing spring 530 that biases the plunger 520 in the projecting direction with respect to the housing main body 510, and a cam guide groove 512 formed on the distal end side of the plunger sliding hole 511 are loosely inserted into the housing 510. A wedge-shaped cam tip 540 that meshes with a rack 521 that is engraved at opposing positions that divide the outer periphery of the plunger 520 into two parts, and a cam that is loosely fitted to the plunger 520 and urges the wedge-shaped cam chip 540 to be pushed into the plunger sliding hole 511. A biasing spring 550 and a cam biasing spring disposed in contact with the opening tip side of the plunger sliding hole 511 50, and when the chain is extended during engine operation, the plunger 520 sequentially advances one tooth at a time, thereby regulating an appropriate backstop amount (backlash amount), and the chain. In addition, the noise that tends to be generated is suppressed and an appropriate chain tension is maintained (for example, see Patent Document 1).
[0003]
[Patent Document 1]
Japanese Patent Application No. 2002-091895 (first page, FIG. 2 to FIG. 3)
[0004]
[Problems to be solved by the invention]
However, in the conventional chain tension applying device 500 as described above, when an external force is applied to push back the plunger 520 from the chain side, the rack 521 of the plunger 520 is engaged with the wedge-shaped cam chip 540 so that the plunger 520 is removably engaged. The plunger 520 that exerts such a backstop function that prevents the back displacement of the projection biasing spring 530, the sealing plate 560, and the cam biasing spring 550 is provided. Is inserted so as to be slidably inserted into the plunger sliding hole 511 of the housing main body 510, but is not designed to prevent the plunger sliding hole 511 from coming off.
[0005]
Therefore, when the conventional chain tension applying device 500 attached inside the engine is once removed from the inside of the engine and the engine is serviced, inspected, and adjusted, the plunger 520 protruding from the housing body 510 has a protruding biasing spring 530. Or the cam biasing spring 550, or the like, due to inadvertent protruding biasing force or being caught by contact with the inside of the engine, the plunger slides out of the hole 511 as shown in FIG. Since there is a risk of falling into the engine, there is a troublesome handling problem that a great degree of skill is required for this removal work, and when the plunger 520 is dropped inside the engine, The engine must be disassembled once and the remaining plunger 520 must be removed. There is a problem that extra spend the time to repair and work man-hours.
[0006]
Further, the conventional chain tension applying device 500 urges the wedge cam tip 540 to push into the plunger sliding hole 511 and restricts the wedge cam tip 540 from projecting in the plunger protruding direction. The wedge-shaped cam tip 540 must be disposed on the tip side, the compaction of the entire tensioner cannot be expected, it cannot be installed in a narrow space on the engine layout, and occurs when it is temporarily removed from the mounted engine interior as described above. There was a problem that the inconvenience to be obtained occurred more frequently.
[0007]
Accordingly, an object of the present invention is to eliminate the problems of the prior art as described above, and to provide a chain tension that is compact and easy to handle by preventing the plunger from being detached from the housing body when being attached to and detached from the engine. Is to provide a device.
[0008]
[Means for Solving the Problems]
First, a chain tension applying device according to a first aspect of the present invention includes a plunger that protrudes forward and backward toward a traveling chain, and a housing body provided with a plunger sliding hole into which the plunger is inserted and retracted. A protrusion biasing spring that biases the plunger in the protruding direction with respect to the housing body, and a cam that is externally fitted to the plunger in the enlarged diameter recess on the tip opening side of the plunger sliding hole and is displaced in the axial direction of the plunger A receiving ring, a cam receiving ring urging spring that urges the cam receiving ring in the protruding direction of the plunger, and slides in a slope-shaped cam guide groove formed in the cam receiving ring, and on the outer peripheral surface of the plunger. A plurality of wedge-shaped cam chips that respectively mesh with a plurality of carved racks, and a plunger rack in the diameter-opening recess on the tip opening side of the plunger sliding hole The plunger is fitted to restrict the engagement of a plurality of wedge-shaped cam chips, and the plunger is retained at the rack end step formed between the outer peripheral surface of the plunger and the rack blade edge surface to prevent the plunger from coming out of the plunger sliding hole. A cam guide ring, a cam receiving ring biasing spring, a cam receiving ring, a wedge-shaped cam tip, and a cam that are inserted into the plunger sliding hole in a diameter-enlarged concave portion in order to be able to advance and retract. By providing a sealing plate that encloses the guide ring so as to be movable, the above-described problems are solved.
[0009]
In the chain tension applying device according to the second aspect of the present invention, in addition to the configuration described in the first aspect, the cam guide ring is slidably aligned with the outer peripheral surface including the rack blade edge surface of the plunger. By providing the inner peripheral surface, the above-described problems are further solved.
[0010]
The chain tension applying device of the present invention may be either a chain tension applying device that is hermetically mounted inside the engine, referred to as an interior type, or a chain tension applying device that is inserted and mounted from outside the engine, referred to as an exterior type. In particular, in the case of the exterior type, the effect of preventing the plunger from coming off can be further exhibited.
[0011]
Further, the chain tension applying device of the present invention has been described with respect to a transmission timing chain hung between the crankshaft side sprocket and the camshaft side sprocket of the engine. Needless to say, the present invention can be applied not only to the system but also to a chain wound around a balancer system, an oil pump system, or the like inside the engine, and also to a transmission timing belt.
[0012]
Further, the cam guide ring in the chain tension applying device according to the present invention is adapted to guide and restrict the disengagement of a plurality of wedge-shaped cam tips by being fitted on the plunger rack within the enlarged diameter recessed portion on the tip opening side of the plunger sliding hole. The cross-sectional shape of the plunger corresponds to the shape of the plunger as long as it can be locked to the rack end step portion formed between the outer peripheral surface of the plunger and the rack blade edge surface to prevent the plunger from coming out of the plunger sliding hole. The ring shape may be any shape such as a rectangular ring shape, an annular shape, an elliptical shape, etc. For example, in the case of an annular one, it is more preferable to adopt a C-shaped ring.
The ring material may be made of metal, but a synthetic resin called engineering plastic resin from polyamide resin, acrylic resin, or the like is more preferable because it can suppress contact noise and contact wear with other members.
[0013]
In addition, with respect to the protrusion biasing spring in the chain tension applying device of the present invention, if it is possible to bias the plunger in the protruding direction with respect to the housing body, it is possible to provide a gap between the tip of the plunger and the sealing plate. Alternatively, it may be interposed between the rear end portion of the plunger and the bottom portion of the plunger sliding hole, but the latter can further reduce the size of the tensioner body.
[0014]
[Action]
According to the chain tension applying device of the present invention, when the chain extends during engine operation, the plunger moves forward one tooth at a time, thereby regulating an appropriate backstop amount (backlash amount). Prevents abnormal noise and the noise generated when the chain is too tight to maintain proper chain tension.
[0015]
That is, in the chain tension applying device of the present invention, when the traveling chain is relaxed, the protrusion biasing spring is extended from the back stop state in which the plunger is prevented from moving backward, and the plunger is immediately advanced. Go. At this time, the cam receiving ring in the enlarged diameter recessed portion at the tip opening side of the plunger sliding hole is also displaced in the protruding direction of the plunger by the cam receiving ring biasing spring, and a plurality of wedge-shaped cam tips are associated with the displacement of the cam receiving ring. Also, the plunger moves in the protruding direction of the plunger while being engaged with the rack of the plunger. Then, the plurality of wedge-shaped cam chips slide the cam guide ring on the rack blade edge surface of the plunger and displace it in the protruding direction of the plunger.
[0016]
Next, when the cam guide ring comes into contact with the back surface of the sealing plate in the enlarged diameter recess on the tip opening side of the plunger sliding hole and stops, the wedge-shaped cam tip slides in the slope-shaped cam guide groove of the cam receiving ring. Then, while pushing back the cam receiving ring in the direction opposite to the protruding direction of the plunger, the cam receiving ring urges toward the outer periphery of the ring until the plunger is disengaged from the rack.
[0017]
At the moment when the engagement between the wedge-shaped cam tip and the rack of the plunger is disengaged, the cam-guiding ring comes into contact with the back surface of the sealing plate and stops, so the wedge-shaped cam tip changes completely and the slope-shaped cam of the cam receiving ring. Sliding in the guide groove until it engages with the plunger rack at a position shifted by one tooth, it sinks toward the plunger axis, and the cam receiving ring is displaced again in the plunger protruding direction by the reaction. .
[0018]
In such a state, when an external force that pushes back the plunger from the chain side is applied to the chain tension applying device of the present invention, the plurality of wedge-shaped cam tips that have moved over the plunger rack by one tooth will move the plunger rack by one tooth. As before, it has a wedge action on the plunger and exhibits a backstop function that prevents the plunger from moving backward.
[0019]
In addition, when the above-described backstop function is activated, a wedge-shaped cam chip that engages with a plurality of racks respectively carved at opposite positions that divide the outer periphery of the plunger into at least two parts is pushed back through the plunger. A force is evenly applied to the wedge cam tip and distributed.
[0020]
Thus, the retaining of the plunger, which is the most characteristic feature of the chain tension applying device according to the present invention, will be described in detail. It is externally fitted, and even if the plunger tries to jump out of the housing body excessively, it is locked to the rack end step portion formed between the outer peripheral surface of the plunger and the rack blade edge surface. Prevent the plunger from coming off.
[0021]
Further, since the inner peripheral surface of the cam guiding ring is aligned with the outer peripheral surface including the rack cutting edge surface of the plunger, the cam guiding ring is slid on the rack cutting edge surface while being prevented from rotating with respect to the outer periphery of the plunger. Since the contact displacement occurs and the rack end step is locked, the plunger that is about to jump out of the housing body is completely prevented from coming off.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, one example in a preferred embodiment of a chain tension applying device of the present invention will be described with reference to the drawings. Here, FIG. 1 is an installation view of a chain tension applying device according to an embodiment of the present invention, FIG. 2 is a schematic view in which the chain tension applying device shown in FIG. 1 is partially broken, and FIG. 1 is an exploded view of the chain tension applying device shown in FIG. 1, FIG. 4 is an enlarged cross-sectional view of the main part of the chain tension applying device shown in FIG. 2, and FIGS. 5 to 11 are shown in FIG. FIG. 5 is a cross-sectional view showing the operating state of the backstop function, and FIG. 6 is a diagram illustrating the state until the wedge-shaped cam tip starts to be disengaged from the rack of the plunger. FIG. 7 is a sectional view showing the operating state immediately before the wedge-shaped cam tip rides over one rack of the plunger, and FIG. 8 is a sectional view of the plunger advanced by one tooth of the rack. Shown immediately after operation FIG. 9 is a cross-sectional view showing an operating state of the backstop function after the plunger has advanced by one tooth of the rack, and FIG. 10 shows a state in which the plunger is prevented from being detached in this embodiment. It is sectional drawing which showed.
[0023]
The chain tension applying device 100 according to the present embodiment suppresses vibrations generated when the timing chain TC is run between the crankshaft side sprocket S1 and the camshaft side sprocket S2 of the automobile engine as shown in FIG. In addition, in order to maintain an appropriate tension, it is used as an external chain tensioning device that is inserted and mounted from the outside of the engine, and is a timing for traveling in front of the housing main body 110 that is mounted on the engine block wall E. A plunger 120 that protrudes toward the chain TC and is biased by a spring presses the back surface of the tensioner lever TL in the vicinity of the swinging end of the tensioner lever TL that is pivotally supported by the engine block wall E, so that the shoe of the tensioner lever TL As the surface slides on the slack side of the timing chain TC to add tension You have me.
1 is a tensioner guide that is fixed to the engine block wall E and guides the timing chain TC so as not to flutter.
[0024]
Therefore, as shown in FIGS. 2 to 4, the chain tension applying device 100 of this embodiment includes a housing main body 110 in which a cylindrical plunger sliding hole 111 into which a columnar plunger 120 is removably inserted is formed. A protrusion urging spring 130 that urges the plunger 120 in the protruding direction with respect to the housing body 110, and a plunger 120 that is externally fitted to the plunger 120 within the diameter-opening recess 111a on the distal end side of the plunger sliding hole 111. 120, a cam receiving ring 140 that is displaced in the axial direction of 120, a cam receiving ring biasing spring 150 that biases the cam receiving ring 140 in the protruding direction of the plunger 120, and a slope-shaped cam formed on the cam receiving ring 140. Two stripes carved at opposing positions that slide in the guide groove 141 and divide the outer periphery of the plunger 120 into two parts A pair of wedge-shaped cam tips 160 and 160 that mesh with the racks 121 and 121, respectively, and a pair of wedge-shaped cam tips 160 and 160 are disengaged by being externally fitted to the plunger 120 within the enlarged diameter concave portion 111a on the distal end opening side of the plunger sliding hole 111. Made of synthetic resin that is locked to the rack end step 122 formed between the outer peripheral surface 120a of the plunger 120 and the rack blade edge surface 121a and prevents the plunger 120 from coming out of the plunger sliding hole 111. A cam guide ring 170, a cam receiving ring urging spring 150 and a cam receiving ring 140, which are inserted into the enlarged diameter concave portion 111a of the plunger sliding hole 111 in sequence while the plunger 120 is inserted and removably inserted. And wedge-shaped cam tips 160, 160 and cam guide ring 170 are movable And a sealing plate 180 to encapsulate.
[0025]
In particular, the cam guide ring 170 in the chain tension applying device of the present embodiment is an annular one having an inner peripheral surface 170a slidably aligned with an outer peripheral surface including the rack blade edge surface 121a of the plunger 120. Moreover, a C-shaped ring in which a notch 171 is formed to be externally fitted to the rack 121 of the plunger 120 at the time of assembling and manufacturing is employed.
The cam guide ring 170 of this embodiment is made of synthetic resin, so that the friction coefficient with the plunger 120 and the wedge-shaped cam chip 160 is kept low, and the sliding operation with the plunger 120 and the sliding of the wedge-shaped cam chip 160 are performed. The operation is smooth and the followability is improved, but it may be made of metal.
[0026]
In addition, as for the installation form of the protrusion biasing spring 130, an installation form interposed between the rear end portion of the plunger 120 and the bottom portion of the plunger sliding hole 111 is adopted. If the plunger 120 can be urged in the protruding direction, the plunger 120 may be interposed between the tip of the plunger 120 and the sealing plate 180. The protrusion biasing spring 130 is a spring for biasing the plunger 120 in the protruding direction with respect to the housing body 110 in accordance with the traveling chain tension. It goes without saying that a larger urging force can be sufficiently exerted than the cam receiving ring urging spring 150 for urging in the protruding direction.
[0027]
A hydraulic valve mechanism 190 is provided at the rear end of the housing main body 110 to finely adjust the protruding biasing force of the plunger 120 by applying hydraulic pressure to the rear end of the plunger 120 from an external oil supply source (not shown). The hydraulic valve mechanism 190 includes a ball seat 191 press-fitted into a retainer 193, which will be described later, a check ball 192 that can come into contact with the ball seat 191, a retainer 193 that holds the check ball 192, and the like. And allows the oil to flow into the high-pressure oil chamber 195 formed between the plunger sliding hole 111 and the rear end of the plunger 120, while preventing the oil from flowing back from the high-pressure oil chamber 195. The application and maintenance of the chain tension via the plunger 120 can be achieved more finely.
[0028]
The chain tension applying device 100 of the present embodiment obtained as described above is shown in FIG. 6 when the timing chain TC relaxes from the state where the back stop function of the plunger 120 as shown in FIG. 5 is activated. As shown, the plunger 120 biased in the projecting direction by the projecting biasing spring 130 advances immediately.
[0029]
That is, when the plunger 120 advances from the backstop state toward the timing chain TC in which the plunger 120 travels, as shown in FIG. 6, the cam receiving ring 140 in the tip opening side enlarged recess 111a also has a cam receiving ring. The plunger 120 is displaced in the protruding direction of the plunger 120 by the biasing force of the biasing spring 150, and the pair of wedge-shaped cam chips 160, 160 and the cam guiding ring 170 are also moved to the tip of the plunger sliding hole 111 in accordance with the displacement of the cam receiving ring 140. It fluctuates in the protruding direction of the plunger 120 inside the opening-side enlarged recess 111a.
[0030]
Next, when the cam guide ring 170 comes into contact with the back surface of the sealing plate 180 in the diameter-opening recess 111a on the tip opening side of the plunger sliding hole 111 and stops, as shown in FIG. The cam tips 160, 160 slide in the two sloped cam guide grooves 141, 141 formed in the cam receiving ring 140 to push the cam receiving ring 140 in the direction opposite to the protruding direction of the plunger 120, while Until it is disengaged from the racks 121, 121, it moves toward the outer periphery of the ring.
[0031]
Then, at the moment when the engagement between the pair of wedge-shaped cam chips 160, 160 and the racks 121, 121 of the plunger 120 is disengaged, the cam guiding ring 170 is within the enlarged diameter recess 111 a on the tip opening side of the plunger sliding hole 111 and the sealing plate 180. As shown in FIG. 8, the pair of wedge-shaped cam tips 160, 160 are completely changed in the slope-shaped cam guide grooves 141, 141 of the cam receiving ring 140, as shown in FIG. Each cam slides into the axial center side of the plunger 120 until it slides and meshes with the rack 121, 121 of the plunger 120 at a position shifted by one tooth. Displace again in the direction.
[0032]
Here, when an external force F that pushes back the plunger 120 from the chain side is applied in a state where the cam receiving ring 140 is displaced in the protruding direction of the plunger 120, a pair of wedge-shaped cam tips that have overcome the rack 121 of the plunger 120 by one tooth. As shown in FIG. 9, 160 and 160 are backstops that exert a wedge action f <b> 1 on the plunger 120 and prevent the plunger 120 from moving backward as before the rack 121 of the plunger 120 is moved over by one tooth. Demonstrate the function.
[0033]
In this way, the chain tension applying device 100 of the present embodiment exhibits an appropriate backstop function by advancing the plunger 120 sequentially by one tooth when the chain running during engine operation extends. Plunger 120 caused by fluttering of the chain and excessive noise of the chain due to excessive jumping out of the plunger 120 can be prevented, and appropriate chain tension can be maintained, and the plunger 120 advanced sequentially by one tooth. As shown in FIG. 10, the rack end step portion formed between the outer peripheral surface 120a of the plunger 120 and the rack blade edge surface 121a, even if the rack 121 is further advanced beyond the meshing position where the wedge-shaped cam chip 160 is disposed. Because it can be locked to 122, it can be mounted inside the engine. The effect is enormous, for example, when the plunger 120 that is about to jump out of the housing body 110 can be completely prevented from being detached.
[0034]
【The invention's effect】
The chain tension applying device according to the present invention includes a plurality of wedge-shaped cam chips that slide in the slope-shaped cam guide groove and mesh with the rack on the outer periphery of the plunger. By moving forward one tooth at a time, an appropriate backstop amount (backlash amount) is regulated to prevent abnormal noise during start-up, and to prevent the noise caused by excessive chain tension. The chain tension can be maintained, and in addition to this, the following specific effects are exhibited.
[0035]
First, it is fitted on the rack blade edge surface of the plunger in the enlarged diameter recess on the tip opening side of the plunger sliding hole to guide and restrict the engagement of a plurality of wedge-shaped cam chips, and between the outer peripheral surface of the plunger and the rack blade edge surface. The cam guide ring that locks the plunger at the rack end step formed on the plunger and prevents the plunger from coming out of the plunger sliding hole allows the plunger's outer periphery to move out of the housing body. Since it is locked to the rack end step formed between the surface and the rack blade edge surface, the plunger that tries to jump out of the housing body can be prevented from being detached when attaching to and removing from the engine. The engine must be removed from the inside of the engine, which required a great degree of skill when maintaining, inspecting and adjusting the engine. This can be done in a real and simple manner, and the maintenance work burden can be significantly reduced.
[0036]
And a cam receiving ring that shifts in the axial direction of the plunger within the enlarged diameter recess on the tip opening side of the plunger sliding hole, a cam receiving ring biasing spring that biases the cam receiving ring, and a slope of the cam receiving ring A wedge-shaped cam chip that slides in the groove-shaped cam guide groove and meshes with the rack of the plunger, and a cam guide ring that guides and regulates the disengagement of the wedge-shaped cam chip. Compared with the case where a conventional cam urging spring is used, there is no unbalanced movement of each wedge-shaped cam tip, and only one wedge-shaped cam tip meshes with the rack of the plunger. It is avoided and cam durability is further improved.
[0037]
In addition, by adopting a structure that can adopt a cam guiding ring instead of the conventional cam biasing spring, the tensioner structure on the tip side from the wedge-shaped cam tip can be simplified, and the rack is engraved. Since the plunger length on the distal end side can be shortened, a chain tension applying device that is compact and easy to handle can be realized.
[0038]
Furthermore, the chain tension applying device according to claim 2 is aligned with the outer peripheral surface including the rack blade edge surface of the plunger in addition to the effect of the invention according to claim 1 as described above. Because the cam guide ring is locked against the outer periphery of the plunger, it slides and displaces on the rack blade edge surface and is securely locked to the rack end step, so it will pop out of the housing body. The plunger can be completely retained.
[Brief description of the drawings]
FIG. 1 is an installation view of a chain tension applying device according to an embodiment of the present invention.
FIG. 2 is a schematic view in which the chain tension applying device shown in FIG. 1 is partially broken.
3 is an exploded view of the chain tension applying device shown in FIG. 1. FIG.
4 is an enlarged cross-sectional view of a main part of the chain tension applying device shown in FIG.
FIG. 5 is a sectional view showing an operating state of a backstop function.
FIG. 6 is a cross-sectional view showing an operating state until the wedge-shaped cam tip starts to disengage from the rack of the plunger.
FIG. 7 is a cross-sectional view showing the operating state immediately before the wedge-shaped cam tip has moved over one rack of the plunger rack.
FIG. 8 is a sectional view showing an operating state immediately after the plunger has advanced by one tooth of the rack.
FIG. 9 is a cross-sectional view showing an operating state of the backstop function after the plunger has advanced by one rack tooth.
FIG. 10 is a cross-sectional view showing a state in which the plunger is prevented from coming off.
FIG. 11 is a schematic view in which a conventional chain tension applying device is partially broken.
12 is an exploded view of the chain tension applying device shown in FIG.
FIG. 13 is a cross-sectional view showing a state where the plunger is not retained in the conventional chain tension applying device.
[Explanation of symbols]
100,500 ... Chain tension applying device
110, 510 ・ ・ ・ Housing body
111,511 ... Plunger sliding hole
111a ... Diameter-opening recess on the tip opening side of the plunger sliding hole 111
120, 520 ... Plunger
120a ... The outer peripheral surface of the plunger 120
121,521... Rack
121a ... Rack edge surface
122 ・ ・ ・ Rack end step portion
130, 530... Biasing spring
140 ・ ・ ・ Cam receiving ring
141,512 ・ ・ ・ Slope cam guide groove
150 ・ ・ ・ Cam receiving ring biasing spring
160,540 ... Wedge cam tip
170 ・ ・ ・ Cam guiding ring
170a ... Inner peripheral surface of cam guide ring 170
171 ... Notch
180,560 ... sealing plate
190,570 ... Hydraulic valve mechanism
191 571 Ball seat
192,572 ・ ・ ・ Check ball
193,573 ... Retainer
195,580 ... High pressure oil chamber
550... Cam biasing spring
S1 ... Drive shaft side sprocket
S2 ... Driven shaft side sprocket
TC Timing chain
TG Tensioner guide
TL Tensioner lever
E ... Engine block wall

Claims (2)

A plunger that protrudes forward and backward toward the traveling chain, a housing main body provided with a plunger sliding hole into which the plunger is removably inserted, and a protrusion that urges the plunger in the protrusion direction with respect to the housing main body An urging spring, a cam receiving ring that is externally fitted to the plunger in the enlarged diameter recess on the tip opening side of the plunger sliding hole, and is displaced in the plunger axial direction, and urges the cam receiving ring in the protruding direction of the plunger. A cam receiving ring biasing spring, a plurality of wedge cam tips that slide in slope cam guide grooves formed in the cam receiving ring and mesh with a plurality of racks formed on the outer peripheral surface of the plunger, respectively. Inducting regulation of a plurality of wedge-shaped cam chips is guided by being externally fitted to the plunger rack in the diameter-enlarged recess on the tip opening side of the plunger sliding hole. In addition, a cam guide ring for locking the plunger from the plunger sliding hole by locking with a rack end step formed between the outer peripheral surface of the plunger and the rack blade edge surface, and the plunger is inserted in a freely reciprocating manner. And a cam receiving ring biasing spring, a cam receiving ring, a wedge-shaped cam chip, and a sealing plate that movably encloses the cam guiding ring, which are sequentially arranged in the enlarged diameter concave portion on the tip opening side of the plunger sliding hole. A chain tension applying device characterized by that. The chain tension applying device according to claim 1, wherein the cam guide ring includes an inner peripheral surface slidably aligned with an outer peripheral surface including a rack blade edge surface of the plunger.

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