JP2503111Y2 - Tensioner for toothed belt - Google Patents

Description

TECHNICAL FIELD The present invention relates to a tensioner for a toothed belt, and particularly when used in a toothed belt for driving a camshaft of an engine,
The present invention relates to a tensioner for a toothed belt that can quickly eliminate looseness of the belt.

2. Description of the Related Art Generally, it is necessary to apply an appropriate tension to the toothed belt to prevent skipping. For example, when the toothed belt is used to drive the camshaft of the engine, the ambient temperature changes over a wide range, and due to the difference in the linear expansion coefficient between the toothed belt and the engine body, the belt tension becomes too large or too small when used at both extremes. Since it is easy to generate vibration, noise, skipped stitches, etc., the tension of the belt must be kept within an appropriate range by using a tensioner.

Applicant has adopted such a tensioner as the actual breaker 62-403.
We have already proposed the idea of No. 54 (Jpn. App. No. 60-131591). The invention of this prior application is that a piston rod is fixed to a piston that is loosely fitted in an oil-filled cylinder with a small gap, and a protruding force is applied to this rod by a spring, and the piston front chamber in the cylinder is divided by the piston. In a tensioner in which a check valve that allows oil to flow into the piston rear chamber is provided in an oil passage that communicates with the piston rear chamber, an oil reservoir (oil reservoir) that communicates with the piston front chamber is covered by a diaphragm.

In the present invention, the terms high pressure chamber and low pressure chamber will be used hereinafter. The high-pressure chamber is a chamber that resists the reaction force of the toothed belt and is represented as a piston rear chamber in the tensioner. The low-pressure chamber is a chamber that does not receive the reaction force of the belt, and its main function is to supply oil to the high-pressure chamber.
In the above tensioner, it is represented as a piston front chamber. There is also a tensioner in which the front chamber of the piston is a high pressure chamber and the rear chamber of the piston is a low pressure chamber.

In the tensioner, the oil reservoir and the diaphragm are provided in the piston front chamber, that is, the low pressure chamber side. When the tension of the belt is released and the piston rod projects, the hydraulic pressure in the low pressure chamber mainly acts on the diaphragm. This is because the sectional area of the opening passage between the low pressure chamber and the oil reservoir is larger than the sectional area of the oil passage between the low pressure chamber and the high pressure chamber. The check valve opens after an increase in hydraulic pressure that results from the piston rod pushing the diaphragm in an attempt to protrude. At this time, the diaphragm is in the process of deforming to the outside (atmosphere side), and the high pressure chamber has a negative pressure.

As described above, in the conventional tensioner, the diaphragm is forced to perform the reciprocating operation of the outward deformation due to the hydraulic pressure rise of the low pressure chamber and the inward deformation due to the inflow of oil into the high pressure chamber. In this case, the diaphragm will be deformed. Also, the cross-sectional area of the oil reservoir is larger than the cross-sectional area of the low-pressure chamber, and increasing the hydraulic pressure just to open the check valve requires a larger forward movement of the piston rod. ) Occurs.

An object of the present invention is to provide a tensioner that can quickly respond to changes in belt tension by eliminating the deformation of the diaphragm and the time lag of piston rod protrusion.

Means for Solving the Problems The present invention is directed to a cylinder filled with oil, a piston that is loosely fitted in the cylinder with a small gap to divide the cylinder into a low pressure chamber and a high pressure chamber, and a protrusion output by a spring fixed to the piston. A piston rod provided with an oil passage, an oil passage communicating the low pressure chamber and the high pressure chamber, a check valve provided in the oil passage for allowing oil to flow into the high pressure chamber, and a check valve provided on the low pressure chamber side. The above problems are solved by a tensioner for a toothed belt, which has a diaphragm and an orifice that is provided between the oil passage and the diaphragm and has a flow passage cross-sectional area that is significantly smaller than that of the oil passage.

Action When the toothed belt slackens, the piston and piston rod tend to project in response to this slack. In the tensioner of the present invention, the flow of the oil in the low pressure chamber is restricted by the viscous resistance of the orifice at the moment of the projecting operation, and the rise of the hydraulic pressure acting on the diaphragm is delayed. The oil passage between the low pressure chamber and the high pressure chamber is sufficiently larger than the cross-sectional area of the orifice, and the hydraulic pressure between the piston and the orifice in the low pressure chamber acts mainly on the oil passage side to open the check valve. The hydraulic pressure hardly acts on the diaphragm.

In this way, the check valve opens at the moment when it is desired to eliminate the looseness of the belt, so that the oil flow from the low pressure chamber side to the high pressure chamber side occurs immediately and with high responsiveness, which enables a quick operation of the piston rod. Obtainable.

Embodiment 1 FIG. 1 is a view showing a first embodiment of the present invention. A support plate 13 supporting a roller 12 pressed against the return side portion of the toothed belt 11 is pivotally attached to a fixing member with a bolt 14, and a supporting plate is provided with a piston rod 21 of a cylinder 20 attached to the fixing member with a mounting portion 15. Pressurize 13 to tension belt 11.

The cylinder 20 of the tensioner 10 of this embodiment has a front reservoir portion 22, a rear body portion 23, and a piston 24 that is loosely fitted with a small gap, and the rod 21 is press-fitted and fixed to the piston 24.

Seal to prevent leakage of oil 25 filled in cylinder 20
26 are provided.

The piston 24 is provided with an oblique hole 33 which is a part of an oil passage that connects the low pressure chamber 31 and the high pressure chamber 32.

A valve seat 35 is fitted on the left side of the piston 24.
The valve seat 35 is connected to the oblique hole 33 and the oblique hole 33.
Along with this, a vertical hole 36 that constitutes an oil passage that connects the low pressure chamber 31 and the high pressure chamber 32 is provided. A spring 42 is interposed between the retainer 37 and the end surface of the cylinder main body 23, and a ball 38 held in the center of the retainer 37 is pressed against the opening of the vertical hole 36 by a weak spring 39, so that the low pressure chamber 31 A check valve 40 is configured to allow the oil 25 to flow into the high pressure chamber 32. Reference numeral 41 denotes an oil reservoir, which is a low pressure chamber 31 when the piston 24 moves through the hole 43.
The difference in volume change between the high pressure chamber 32 and the high pressure chamber 32 is absorbed.

The tensioner 10 of the present invention further includes an annular member 27 in the low pressure chamber 31 between the opening 34 of the oil passage 33 and the hole 43 of the oil reservoir 41. The annular member 27 is located on the piston 24 side of the hole 43 so as to be adjacent to the hole 43. The shape is a ring shape with a part cut away, as shown in FIGS. 2 and 3. The outer diameter is a recess 28 in the cylinder 20.
The diameter of the flow passage cross-sectional area is significantly smaller than that of the oil passage between the recess 28 and the outer periphery of the piston rod 21 when the annular member 27 is fitted in the recess 28. It has such a diameter that it constitutes an orifice 29 having it. The width of the notch 30 need only be large enough to contract the annular member 27 to fit into the recess 28, and also functions as an orifice after fitting into the cylinder 20.

Although not shown, a step portion that opens to the right in the figure is provided in the cylinder 20, and a complete ring-shaped annular member is abutted against this step portion and fixed by a core metal of a seal or the like to form an orifice. You may

The operation of the tensioner 10 will be described below assuming that the annular member 27 and the orifice 29 are not provided.

The spring 42 is provided with the toothed belt 11 via the rod 21, the roller 12, etc.
When the belt 11 is stretched or the ambient temperature decreases and the belt tension decreases, the spring 42 causes the rod 21 to
Moves forward to restore the belt tension to almost the original value. In this case, the forward movement of the rod 21 raises the hydraulic pressure in the low-pressure chamber 31 to open the check valve 40, so that the rod 21 can be moved forward to restore the belt tension reduction.

When the toothed belt 11 is used to drive the camshaft of the engine, the tension of the belt 11 increases for a short time and the rod 21 retreats when the engine starts to rotate in the reverse direction (within one rotation) when the engine is started. Receive a great reaction force in the direction. However, since the check valve 40 is closed, the rod 21 cannot be rapidly retracted, and the oil flows through the small gap around the piston to gradually retract the rod 21 to balance the reaction force and the force of the spring 42. Settle in the position where you want to. Therefore, with respect to the reverse rotation of the engine for a short time, the roller 12 does not retreat to a large extent, and skipping due to loosening of the belt does not occur.

The orifice 29 of the present invention works effectively when the rod 21 projects during the above operation. That is, when the rod 21 is projected, the oil 25 on the low pressure chamber 31 side is trapped by the piston 24 and the annular member 27 and hardly acts on the diaphragm 44. oil
25 cannot flow except through the orifice 29, and this increase in hydraulic pressure causes the check valve 40 to open instantly. Therefore, the inflow of the oil 25 into the high-pressure chamber 32 side immediately responds to the protrusion of the rod 21 without a time lag, so that the responsivity to the looseness of the toothed belt 11 is significantly improved.

Further, the annular member 27 serves as a stopper when the piston 24 reaches the right end, and further guides the air intruding from the seal 26 to the oil reservoir 41 so as to prevent the functional deterioration due to air mixing in the high pressure chamber 32. It also has functions.

4 and 5 show a modified example of an annular member forming an orifice, in which a cylindrical portion 46 having an edge 45 is continuous with a ring-shaped portion 48 by a chamfered portion 47.
The annular member 49 causes a difference in viscous resistance due to the difference in the flowing direction of the oil 25.

FIG. 6 shows a second embodiment of the present invention and is an enlarged sectional view of the reservoir portion.

In the present embodiment, the hole that passes through the low pressure chamber 31a and the oil reservoir 41a is used as the orifice 29a.

FIG. 7 shows a third embodiment of this embodiment, and is an enlarged cross-sectional view of the reservoir section.

The orifice of this embodiment is configured with a valve. The oil reservoir 41b has a pressing plate 52 having a hole 51 on the diaphragm 44b side, and a hole 43b to the low pressure chamber 31b and a pressing plate.
A vertically movable valve body 50 is enclosed between 52. Valve 50
As shown in FIG. 8, has a notch 53 in the shape of a cap.

The valve body 50 moves up and down by the hydraulic pressure of the low pressure chamber 31b to restrict the flow of oil to the oil reservoir 41b side,
Allows oil to flow to the side. The valve body 50 normally covers the hole 43b by its own weight. The hole 51 of the pressing plate 52 is not blocked when the rod is slowly projected, but when the rod is rapidly projected, the hole 51 is closed so as to increase the hydraulic pressure of the low pressure chamber 31b, and the check valve is instantaneously opened. Let

Needless to say, the orifice mechanism of the present invention can be applied to a tensioner having a structure in which an oil passage connecting the low pressure chamber and the high pressure chamber is provided in the piston and the piston rod.
In the case of this tensioner, by providing the annular member between the opening on the low pressure chamber side of the oil passage and the diaphragm, the same operation as in the above embodiment can be obtained. In that case, similarly to the above-described embodiment, the communication hole between the low pressure chamber and the oil reservoir may be an orifice, or the orifice may be provided together with the valve body.

The orifice mechanism of the present invention can also be applied to a tensioner in which one end of a cylinder is sealed with a diaphragm to form a low pressure chamber. Such a tensioner is a practical application Sho 63
-141195. That is, as shown in FIG. 9, the tensioner 10 'is provided with an oil-filled cylinder 20' and a cylinder 20 'which is loosely fitted in the cylinder 20' with a small gap so that the cylinder 20 'is placed in the low-pressure chamber 31' and the high-pressure chamber 32. A piston 24 'divided into', a piston rod 21 'fixed to the piston 24' and provided with a protrusion force by a spring 42 ', and a low pressure chamber
An oil passage 33 'and a vertical hole 36' which connect the 31 'and the high pressure chamber 32'.
A check valve 40 'provided in the oil passage 33' and the vertical hole 36 'to allow the oil to flow into the high pressure chamber 32', and a diaphragm 44 'provided on the low pressure chamber 31' side. The structure is such that an annular member 27 'is provided between the diaphragm 44' and the oil passage 33 '.

The orifice 29 'is formed between the outer circumference of the piston rod 21' and the inner circumference of the annular member 27 ', and restricts the flow of oil before and after the annular member 27'. As a result, piston 2
When 4'is projected, the hydraulic pressure acts on the oil passage 33 'side and the vertical hole 36' side as in the above-described embodiment, and immediately opens the check valve 40. Also,
The annular member 27 'also acts as a stopper when the piston 24' reaches the left end.

The orifice is the outer periphery of the stopper 16 for fixing the diaphragm 44 'to the piston rod 21' and the annular member 2.
It can also be formed between the inner circumference of 7 '.

Advantages of the Invention With the above-described configuration, the present invention allows the hydraulic pressure of the low pressure chamber to be increased by the orifice having a flow passage cross-sectional area significantly smaller than that of the oil passage communicating between the low pressure chamber and the high pressure chamber when the piston protrudes. Since the temperature rises temporarily, the check valve opens immediately and the oil flows to the high pressure chamber side quickly. Therefore, the response to the slack of the belt is fast, and the followability of small vibrations is extremely high. When the rod is projected, the diaphragm is less likely to be deformed outward due to the increased hydraulic pressure of the low pressure chamber, and is only deformed inward, so that the hydraulic pressure flows smoothly to the high pressure chamber.

In the tensioner of the second aspect, since the orifice is formed by the annular member, the change from the conventional tensioner is easy and the structure is simple. In addition, there is no change in the external shape and there is a possibility of replacing the conventional tensioner.

In the tensioner of the third aspect, there is an effect that the invading air is guided to the oil reservoir by the annular member.

In the tensioner according to the fourth aspect, the structure can be simplified because only the orifice that connects the low pressure chamber and the oil reservoir needs to be an orifice.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of a tensioner according to the present invention, FIG. 1 is a sectional view of the first embodiment, FIG. 2 is a front view of an orifice attached to the tensioner of FIG. Figure 3 is 3 of Figure 2
-3 line sectional view, FIG. 4 is a front view of a modified example of the orifice shown in FIG. 2, FIG. 5 is a sectional view taken along line 5-5 of FIG. 4, and FIG. 6 is a partially enlarged sectional view of the second embodiment. FIG. 7 is a partially enlarged sectional view of the third embodiment, FIG. 8 is a perspective view of a valve body, and FIG. 9 is a tensioner in which one end of a cylinder is a diaphragm and the orifice mechanism of the present invention is applied to the tensioner. It is a sectional view of a thing. 10 …… Toothed belt tensioner 11 …… Toothed belt 20 …… Cylinder 21 …… Piston rod 22 …… Reservoir section 23 …… Main body section 24 …… Piston 27 …… Annular member 29,29a, 49 …… Orifice 31,31a, 31b …… Low pressure chamber 32,32a, 32b …… High pressure chamber 33,36 …… Oil passage 40 …… Check valve 41,41a, 41b …… Oil reservoir 42 …… Spring 43,43b …… Hole 44 …… diaphragm 50 …… valve

Claims (4)

(57) [Scope of utility model registration request] 1. A cylinder filled with oil, a piston that is loosely fitted in the cylinder with a small gap to divide the cylinder into a low-pressure chamber and a high-pressure chamber, and a piston rod fixed to the piston and provided with a protruding force by a spring. An oil passage that connects the low pressure chamber and the high pressure chamber, a check valve that is provided in the oil passage and allows oil to flow into the high pressure chamber, a diaphragm that is provided on the low pressure chamber side, and A tensioner for a toothed belt, comprising: an orifice provided between an oil passage and the diaphragm, the orifice having a flow passage cross-sectional area significantly smaller than that of the oil passage. 2. The tensioner for a toothed belt according to claim 1, wherein the orifice is formed between an inner circumference of an annular member attached to the cylinder and an outer circumference of the piston rod. 3. The toothed member according to claim 2, wherein the diaphragm covers an oil reservoir communicating with the low pressure chamber, and the annular member is provided between a hole communicating with the oil reservoir and the oil passage. Belt tensioner. 4. The diaphragm covers an oil reservoir communicating with the low pressure chamber, and a hole communicating between the oil reservoir and the low pressure chamber is an orifice.
Tensioner for toothed belt of paragraph.