Rotary Damper

Abstract

The present invention provides a rotary damper provided with a cylinder (10) having a partition (13), and a rotor (20) having a shaft part (21) facing the partition, wherein the cylinder is a casting, and a distal end of the partition and the shaft part have a tapered shape. According to the present invention, it is possible to prevent widening of a gap formed between the partition and the shaft part.

Description

Technical Field

[0001] The present invention relates to a rotary damper and a method for manufacturing the same.

Background Art

[0002] Conventionally, a rotary damper is known which includes a cylinder having a partition wall and a rotor having a shaft portion facing the partition wall, and the cylinder is a casting. In the conventional rotary damper, the shaft portion is designed to have a straight shape, that is, a shape in which the outer diameter is the same over the length direction of the shaft portion, and the tip of the partition wall is also designed to have a straight shape, that is, a shape in which the inner diameter is the same over the length direction of the partition wall. However, in the conventional rotary damper, since the cylinder is a casting, there is a problem that a dent due to external shrinkage is formed on the tip surface of the partition wall. This dent enlarges the gap formed between the partition wall and the shaft portion, which has contributed to the deterioration of the characteristics of the rotary damper.

[0003] Also conventionally, a method for manufacturing a rotary damper including a step of casting a cylinder having a partition wall using a mold is known. However, in the conventional manufacturing method, since the portion of the upper mold of the mold that forms the tip of the partition wall has a straight shape, that is, a shape in which the outer diameter is the same over the length direction of the portion, external shrinkage occurs due to the shrinkage during solidification of the molten metal, and there is a problem that a dent is formed on the tip surface of the partition wall.

[0004] International Publication No. 2003 / 046405 discloses a rotary damper including a cylinder having a partition wall, a rotor having a shaft portion facing the partition wall, a vane protruding from the shaft portion, an oil passage formed in the vane, and a valve that changes the flow rate of oil passing through the oil passage in one direction according to a load. This rotary damper has a characteristic that the operating time, that is, the time required for the rotor or the cylinder to rotate a certain rotation angle hardly changes due to a change in the load. However, when the cylinder is a casting and the partition wall has a recess due to external drawing on its tip surface, there is a problem that the characteristic deteriorates because an insufficient amount of oil for the valve to function is supplied to the valve.

[0005] International Publication No. 2012 / 141242 discloses a rotary damper including a cylinder having a partition wall, a rotor having a shaft portion facing the partition wall, a vane protruding from the shaft portion, an oil passage formed in the vane, and a check valve provided in the oil passage. This rotary damper has a characteristic that a braking force is generated only when the rotor is rotated in one direction. However, when the cylinder is a casting and the partition wall has a recess due to external drawing on its tip surface, there is a problem that the braking force decreases because oil flows out more than expected from the gap formed between the partition wall and the shaft portion when the rotor is rotated in one direction.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] An object of the present invention is to prevent an increase in the gap formed between the partition wall and the shaft portion.

Means for Solving the Problems

[0008] To solve the above problems, the present invention provides the following rotary damper. Pa provided. 1. Peripheral wall, an end wall closing one end of the peripheral wall, and projecting from the peripheral wall toward the center A cylinder having a partition wall, A lid closing the other end of the peripheral wall, A rotor having a shaft portion facing the partition wall, a vane protruding from the shaft portion, a first oil passage formed in the partition wall or the vane, and a valve that changes the flow rate of oil passing through the first oil passage in one direction according to the load, wherein the cylinder is a casting, and the tip of the partition wall is The end wall side whose inner diameter is The lid side a tapered shape smaller than the inner diameter of The end wall side whose outer diameter is The lid side a tapered shape smaller than the outer diameter of 2. Peripheral wall, an end wall closing one end of the peripheral wall, and projecting from the peripheral wall toward the center A cylinder having a partition wall, A lid closing the other end of the peripheral wall, A rotor having a shaft portion facing the partition wall, a vane protruding from the shaft portion, a first oil passage formed in the partition wall or the vane, a valve that changes the flow rate of oil passing through the first oil passage in one direction according to the load, a second oil passage formed in the partition wall or the vane where the first oil passage is not formed, and a check valve provided in the second oil passage that closes the second oil passage when oil passes through the first oil passage in one direction and opens the second oil passage when oil passes through the first oil passage in the reverse direction, wherein the cylinder is a casting, and the tip of the partition wall is The one direction In the same direction a tapered shape smaller than the inner diameter of The end wall side whose inner diameter is The lid side a tapered shape smaller than the inner diameter of The end wall side whose outer diameter is The lid side a tapered shape smaller than the outer diameter of

Advantages of the Invention

[0009] In the present invention described in 1 and 2 above, the cylinder is a casting. However, the tip of the partition wall is End wall side whose inner diameter isLid side Since it has a tapered shape smaller than the inner diameter of , it is possible to prevent a dent due to outward drawing from being formed on the tip surface of the partition wall. According to the present invention described in and above, the shaft portion facing the partition wall also End wall side has an outer diameter of Lid side Since it has a tapered shape smaller than the outer diameter of , it is possible to prevent the gap formed between the partition wall and the shaft portion from expanding. According to the present invention described in above, since it is possible to prevent the gap formed between the partition wall and the shaft portion from expanding as described above, it is possible to supply an amount of oil sufficient for the valve to function to the valve. Therefore, according to the present invention described in , it is possible to reduce the width of the change in the operating time caused by the change in the load. According to the present invention described in above, since it is possible to prevent the gap formed between the partition wall and the shaft portion from expanding as described above, it is possible to prevent a decrease in the braking force generated when the rotor is rotated in one direction. On the other hand, when the rotor is rotated in the reverse direction, it becomes difficult for the oil to pass through the gap formed between the partition wall and the shaft portion. However, according to the present invention described in , since the oil can pass through two oil passages, that is, the first oil passage and the second oil passage, when the rotor rotates in the reverse direction, it is possible to reduce the resistance of the oil acting on the rotor.

Brief Description of the Drawings

[0010]

Figure 1

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Figure 18

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Examples

[0012] As shown in Fig. 1, the rotary damper according to the embodiment includes a cylinder 10 and a rotor 20. The cylinder 10 is a cylindrical component that houses oil inside. The rotor 20 is a rotating component. However, the rotor 20 may not rotate in some cases. When the cylinder 10 is fixed so as not to rotate and the rotor 20 is rotated in one direction, that is, in the clockwise direction in Figs. 1 and 4, the braking action, and when the rotor 20 is fixed so as not to rotate and the cylinder 10 is rotated in the reverse direction, that is, in the counterclockwise direction in Figs. 1 and 4, the braking action is the same.

[0013] The cylinder 10 adopted in the embodiment is a casting. As shown in Figs. 2, 3, 4, and 5, the cylinder 10 has a peripheral wall 11, an end wall 12 that closes one end of the peripheral wall 11, and a partition wall 13 that protrudes from the peripheral wall 11 toward the center. As shown in Figs. 1, 3, 4, and 5, the cylinder 10 has a flange 14 that projects from the peripheral wall 11. The flange 14 is connected to an object that fixes the cylinder 10 so as not to rotate or an object that rotates the cylinder 10. As shown in Figs. 1, 2, and 3, the other end of the peripheral wall 11 is closed by a lid 30. The lid 30 is attached to the cylinder 10 by caulking the end of the peripheral wall 11. As shown in Figs. 2, 3, and 5, the cylinder 10 has a convex portion 15 that protrudes from the end wall 12. As shown in Fig. 2, the tip of the partition wall 13 is tapered. That is, the distance between the two partition walls 13, 13 becomes smaller toward one end so that the inner diameter D1 at one end is smaller than the inner diameter D2 at the other end.

[0014] The rotor 20 adopted in the embodiment is a casting. However, the rotor 20 does not have to be a casting. As shown in Figs. 2, 3, 4, 6, and 7, the rotor 20 has a shaft portion 21 that faces the partition wall 13. As shown in Fig. 7, the shaft portion 21 is tapered. That is, the outer diameter of the shaft portion 21 becomes smaller toward one end so that the outer diameter D3 at one end is smaller than the outer diameter D4 at the other end. The taper angle of the shaft portion 21 is the same as the taper angle of the tip of the partition wall 13.

[0015] As shown in FIGS. 1, 2, 3, and 4, the rotor 20 is installed such that the shaft portion 21 can rotate within the cylinder 10. As shown in FIG. 2, a recess 22 that fits into a convex portion 15 formed in the cylinder 10 is formed at one end of the rotor 20. As shown in FIGS. 1, 2, 3, 4, and 6, a hole 23 into which an object for rotating the rotor 20 or an object for fixing the rotor 20 so as not to rotate is inserted is formed at the other end of the rotor 20. As shown in FIG. 4, the rotor 20 has a vane 24 that protrudes from the shaft portion 21. The vane 24 is configured to have a valve body 71 and a holding portion 25 that holds the valve body 71. As shown in FIGS. 6 and 7, a groove 26 is formed at the tip of the holding portion 25 integrally formed with the shaft portion 21.

[0016] As shown in FIG. 4, four oil chambers partitioned by the partition wall 13 and the vane 24, namely, a first oil chamber 41, a second oil chamber 42, a third oil chamber 43, and a fourth oil chamber 44, are formed inside the cylinder 10. Oil is injected into each of the oil chambers 41 to 44.

[0017] As shown in FIGS. 2, 4, and 5, a first oil passage 51 is formed in the partition wall 13. The first oil passage may be formed in the vane. As shown in FIG. 4, a valve 60 is provided in the first oil passage 51. As shown in FIG. 9, the valve 60 is configured to have a valve body 61 and a valve seat 62. As shown in FIGS. 8 and 9, the valve body 61 is a leaf spring. As shown in FIG. 9, the valve seat 62 is composed of two inclined surfaces 62a and 62b formed in the partition wall 13. By making the inclination angle of one inclined surface 62a different from that of the other inclined surface 62b, this valve 60 increases the distortion of the valve body 61.

[0018] This valve 60 has a function of changing the flow rate of the oil passing through the first oil passage 51 in one direction according to the load. The "oil passing through the first oil passage 51 in one direction" means the oil moving from the first oil chamber 41 to the fourth oil chamber 44 via the first oil passage 51 and the oil moving from the third oil chamber 43 to the second oil chamber 42 via the first oil passage 51. The "flow rate of the oil" means the amount of oil passing through the first oil passage 51 per unit time. The "load" means the force for rotating the rotor 20 in one direction, i.e., the clockwise direction in FIGS. 1 and 4, or the force for rotating the cylinder 10 in the reverse direction, i.e., the counterclockwise direction in FIGS. 1 and 4. The "change" means decreasing the flow rate of the oil according to the increase of the load.

[0019] The pressure of the oil acting on the valve element 61 increases according to the increase of the load. However, the restoring force of the valve element 61 becomes the resistance against the oil pressure. Therefore, according to this valve 60, when the load is large, as shown in FIG. 10, the valve element 61 greatly deforms without closing the first oil passage 51, and the opening degree of the valve 60 is decreased. On the other hand, when the load is small, as shown in FIG. 11, since the deformation amount of the valve element 61 decreases, the opening degree of the valve 60 becomes large. As a result, this valve 60 can make the operation time, i.e., the time required for the rotor 20 to rotate a certain rotation angle in one direction or the cylinder 10 to rotate a certain rotation angle in the reverse direction, substantially constant even if the load changes.

[0020] When the oil moves from the fourth oil chamber 44 to the first oil chamber 41 via the first oil passage 51 and the oil moves from the second oil chamber 42 to the third oil chamber 43 via the first oil passage 51, as shown in FIG. 12, the valve element 61 greatly deforms by the oil pressure, and the opening degree of the valve 60 becomes larger than the initial state shown in FIG. 9. Therefore, this valve 60 can reduce the resistance of the oil acting on the rotor 20 rotating in the reverse direction or the cylinder 10 rotating in one direction.

[0021] As shown in FIGS. 13 and 15, a second oil passage 52 is formed in the vane 24. The second oil passage is formed in a partition wall or a vane where the first oil passage is not formed. The second oil passage 52 is composed of a combination of grooves 71c to 71f formed in the valve body 71 and a groove 26 formed in the holding portion 25. As shown in FIGS. 13 and 15, a check valve 70 is provided in the second oil passage 52. The check valve 70 is configured to have a valve body 71. As shown in FIG. 14, the valve body 71 has an arcuate main body portion 71a and a protruding portion 71b protruding from the main body portion 71a. The main body portion 71a has two grooves 71c and 71d formed on the inner surface, and the protruding portion 71b has a groove 71e formed at the tip and a groove 71f formed on one side surface. As shown in FIGS. 13 and 15, the main body portion 71a is disposed between the peripheral wall 11 and the holding portion 25. The protruding portion 71b is disposed in the groove 26 formed in the holding portion 25. Since there is a play between the groove 26 and the protruding portion 71b, the valve body 71 can move in the circumferential direction. The main body portion 71a of the valve body 71 preferably has elasticity. This is because the gap formed between the peripheral wall 11 and the valve body 71 can be sealed by the elasticity of the main body portion 71a.

[0022] This check valve 70 is configured such that when the rotor 20 rotates in one direction, i.e., clockwise in FIGS. 1 and 4, or when the cylinder 10 rotates in the reverse direction, i.e., counterclockwise in FIGS. 1 and 4, as shown in FIG. 13, the protrusion 71b of the valve body 71 contacts one side surface of the groove 26 of the holding portion 25 to close the second oil passage 52. When the rotor 20 rotates in the reverse direction, i.e., counterclockwise in FIGS. 1 and 4, or when the cylinder 10 rotates in one direction, i.e., clockwise in FIGS. 1 and 4, as shown in FIG. 15, the protrusion 71b of the valve body 71 contacts the other side surface of the groove 26 of the holding portion 25 to open the second oil passage 52. In the rotary damper according to the embodiment, since it is possible to prevent the expansion of the gap formed between the partition wall 13 and the shaft portion 21, it becomes difficult for oil to pass through the gap. However, since the oil can pass through the two oil passages, i.e., the first oil passage 51 and the second oil passage 52, it is possible to reduce the resistance of the oil acting on the rotor 20 or the cylinder 10 when the rotor 20 rotates in the reverse direction or when the cylinder 10 rotates in one direction.

[0023] The manufacturing method of the rotary damper according to the embodiment includes a step of casting a cylinder having a partition wall using a mold. The mold used in this step is a combination of an upper mold and a lower mold. As shown in FIG. 16, the upper mold 80 has a tapered portion 81 for forming the tip of the partition wall into a tapered shape and a recess 82 formed on the surface of the tapered portion 81.

[0024] As shown in FIG. 16, the tapered portion 81 has a tapered shape. That is, the outer diameter of the tapered portion 81 decreases toward one end such that the outer diameter D5 at one end is smaller than the outer diameter D6 at the other end. Since the upper mold 80 has the recess 82 on the surface of the tapered portion 81, it is possible to prevent the occurrence of shrinkage on the tip surface of the partition wall and the formation of a depression due to shrinkage on the tip surface of the partition wall by injecting the molten metal into the recess 82.

[0025] In the casting process of the cylinder, if the shrinkage accompanying the solidification of the molten metal does not occur as designed, a part of the tip of the partition wall will protrude into the depression 82. However, even if such a situation occurs, as shown in FIG. 16, since the diameter D7 of the depression 82 is larger than the outer diameter D5 of one end of the tapered portion 81, demolding is possible.

[0026] In the prior art, the portion of the upper mold that forms the tip of the partition wall (hereinafter referred to as the "forming portion") has a straight shape, that is, a shape with the same outer diameter over the length direction of the forming portion. Therefore, external shrinkage occurs due to the shrinkage during the solidification of the molten metal, and a depression due to external shrinkage is formed on the tip surface of the partition wall. To solve this problem, it is conceivable to form a depression on the surface of the forming portion. However, in the prior art, as shown in FIG. 17, since the diameter D9 of the depression 82' is smaller than the outer diameter D8 of one end of the forming portion 81', if a part of the tip of the partition wall protrudes into the depression 82', demolding becomes impossible. Therefore, in the prior art, a depression 82' cannot be formed on the surface of the forming portion 81'.

[0027] The rotary damper according to the embodiment has a cylinder 10 made of a casting. However, since the tip of the partition wall 13 has a tapered shape, it is possible to prevent a depression due to external shrinkage from being formed on the tip surface of the partition wall 13. Further, since the shaft portion 21 facing the partition wall 13 also has a tapered shape, it is possible to prevent the expansion of the gap formed between the partition wall 13 and the shaft portion 21, thereby improving the characteristics of the rotary damper compared to the prior art.

[0028] FIG. 18 is a graph showing the relationship between the operating time and the load. The difference between the embodiment and the comparative example lies in the shapes of the tips of the shaft portion and the partition wall. In the comparative example, the shapes of the tips of the shaft portion and the partition wall are straight shapes.

[0029] As shown in this graph, in the example, the range of the change in the operating time caused by the change in the load is smaller than that in the comparative example. In this experiment, the difference between the maximum value and the minimum value of the operating time in the comparative example is about 1.5 seconds, while that in the example is about 0.5 seconds, which is about 1 / 3 of that in the comparative example. This result indicates that the example can supply oil to the valve better than the comparative example, and also demonstrates that the example can prevent the expansion of the gap formed between the partition wall and the shaft portion.

Description of the Reference Numerals

[0030] 10 Cylinder 11 Peripheral Wall 12 End Wall 13 Partition Wall 14 Flange 15 Protrusion 20 Rotor 21 Shaft Portion 22 Recess 23 Hole 24 Vane 25 Holding Portion 26 Groove 30 Cover 41 First Oil Chamber 42 Second Oil Chamber 43 Third Oil Chamber 44 Fourth Oil Chamber 51 First Oil Passage 52 Second Oil Passage 60 Valve 61 Valve Body 62 Valve Seat 70 Check Valve 71 Valve Body 80 Upper Mold 81 Tapered Portion 82 Depression

Claims

1. A rotary damper comprising: a cylinder having a peripheral wall, an end wall closing one end of the peripheral wall, and a partition wall protruding from the peripheral wall toward the center; a lid closing the other end of the peripheral wall; a rotor having a shaft portion facing the partition wall; a vane protruding from the shaft portion; a first oil passage formed in the partition wall or the vane; and a valve that changes the flow rate of oil passing through the first oil passage in one direction in accordance with the load, wherein the cylinder is a casting, the tip of the partition wall has a tapered shape with the inner diameter on the end wall side being smaller than the inner diameter on the lid side, and the shaft portion has a tapered shape with the outer diameter on the end wall side being smaller than the outer diameter on the lid side.

2. A rotary damper as described in claim 1, comprising: a second oil passage formed in the partition or the vane in which a first oil passage is not formed; and a check valve provided in the second oil passage, which closes the second oil passage when oil passes through the first oil passage in the same direction as the one direction, and opens the second oil passage when oil passes through the first oil passage in the reverse direction.

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