Patent Description:
Conventionally, for instance, torque hinges have been widely put into practical use to suspend an LCD display of a notebook computer or a cover of a copying machine at a position of any tilt angle with respect to the main unit. Patent Documents <NUM> and <NUM> below disclose an example of torque hinge having an inner ring and an outer ring that have a common rotation axis and a connection member that is disposed between the inner ring and the outer ring so as to disconnectably connect the rings by a required frictional force. Patent Documents <NUM> and <NUM> refer to a so-called frictional torque hinge, where a spring member composed of a metal thin plate is employed as the connection member. The spring member has a spring portion to get close contact with the outer peripheral surface of the inner ring so as to generate the required frictional force. The inner ring and the outer ring are relatively rotatable against the required frictional force applied by the spring member.

For instance, Patent Document <NUM> discloses a bidirectional torque limiter utilizing a coil spring. Patent Document <NUM> discloses a bidirectional torque limiter utilizing a so-called ring spring, and Patent Document <NUM> discloses a bidirectional torque limiter utilizing a so-called tolerance ring. Since the inner ring and outer ring are relatively rotatable against the required frictional force even in the bidirectional torque limiter disclosed in Patent Documents <NUM> to <NUM>, these torque limiters achieve the same effect as a torque hinge.

Patent Document <NUM> discloses a torque hinge comprising an inner ring and an outer ring that have a common rotation axis, the outer ring is inserted into a cylindrical support member so as to be supported by the support member, and coil springs having a pair of hook portions are mounted on the outer peripheral surface of the outer ring.

As described above, the torque hinge may be used as an angle retaining device for suspending a cover at a position of any tilt angle with respect to the main unit, and it may be used also as a rotation transmitter by connecting either the inner ring or the outer ring to the driving-side member and connecting the other ring to the driven-side member. For instance, either the inner ring or the outer ring is connected to an electric motor as a driving-side member while the other ring is connected to a door of a vehicle as a driven-side member, so that the door can be opened and closed by the electric motor. The door may be subjected suddenly to an external force by wind or the like when the door is in an opening/closing operation by the driving torque of the electric motor or when the door is retained at the full-open position or the intermediate open position by the detent torque or the retaining torque of the electric motor. In such a case, the external force applied to the door can be released by the relative rotation of the inner ring and the outer ring, thereby preventing flapping of the door.

In a case where the torque hinge (bidirectional torque limiter) disclosed in any of Patent Documents <NUM> to <NUM> is used as a rotation transmitter, either the inner ring or the outer ring is always connected to the electric motor while the other ring is always connected to the door. As a result, for instance, in a case where there occurs a necessity of opening/closing the door manually due to a failure or the like of the electric motor, the user is required to open/close the door against the so-called required frictional force for the connection member to connect the inner ring and the outer ring or against the detent torque or a retaining torque of the electric motor. In this case, opening and closing the door requires considerable force, making it substantially impossible.

The present invention has been made in view of the above-described fact, and a main technical object thereof is to provide a novel and improved torque hinge capable of switching between a state for rotating two members integrally or relatively against a required frictional force by performing a required operation, and a state for relatively rotating the members without depending on the required frictional force. Means for Solving the Problems:.

As a result of intensive studies, the present inventors have found that the main technical problems can be solved by the following manner. In the structure, specifically, coil springs each having a pair of hook portions are mounted on the outer peripheral surface of an outer ring, and the outer ring is supported by a cylindrical support member. At the same time, a control member for controlling the coil springs is assembled in series in an axial direction with the support member so that the control member is rotatable about a common rotation axis of the inner ring and the outer ring with respect to the support member. The support member and the control member have hook grooves into which each of the pair of hook portions of the coil spring can be fitted, and the coil springs may retain or liberate the outer ring by a required operation.

That is, the present invention provides, as a torque hinge for achieving the main technical objects described above, a torque hinge characterized in that it includes an inner ring and an outer ring that have a common rotation axis, and a connection member disposed between the inner ring and the outer ring so as to connect disconnectably the inner ring and the outer ring by a required frictional force, the inner ring and the outer ring are rotatable integrally or relatively against the required frictional force,.

Preferably, both the coil springs and the control member are arranged one on each axial side of the support member, the support member is assembled with a bevel gear that is rotatable about a support shaft perpendicular to the common rotation axis, and the control member is equipped with arcuate racks extending in the circumferential direction to mesh with the bevel gear. It is preferable in this case that the coil springs arranged at the axial both sides of the support member are composed of wires that are wound in directions opposite to each other when viewed from one axial end. Further it is favorable that the control member has a cylindrical support protrusion to enter between the inner peripheral surface of the outer ring and the outer peripheral surface of the inner ring, and the connection member is supported from the axial both sides by the respective support protrusions of the control members arranged on the axial both sides of the support member. Suitably, the coil springs tighten and retain the outer ring in a state in which the coil springs are mounted on the outer peripheral surface of the outer ring and no force is applied to each of the pair of hook portions, and the control member rotates with respect to the support member so that the coil springs liberate the outer ring. Preferably, the connection member is non-rotatable with respect to the outer ring. In this case, it is suitable that the connection member is retained from the axial both sides by a pair of retainers, and each of the pair of retainers is locked with the outer ring in the circumferential direction by a circumferential locking means. Further, it is favorable that the connection member is a spring member composed of a metal thin plate having spring portions to be in close contact with the outer peripheral surface of the inner ring.

In the torque hinge of the present invention, a pair of hook portions of each of the coil springs mounted on the outer peripheral surface of the outer ring are respectively fitted into the hook grooves formed on a support member for supporting the outer ring and a control member to be assembled in series in the axial direction with the support member. Since the control member is rotatable about the common rotation axis of the inner ring and the outer ring with respect to the support member, it is possible to switch between a state in which the coil springs tighten to retain the outer ring and a state in which the coil springs liberate the outer ring, by relatively rotating the support member and the control member about the common rotation axis.

In a state in which the coil springs tighten and retain the outer ring, the support member is integrated with the outer ring. As a result, the inner ring connected to the outer ring by the required frictional force applied by the connection member becomes rotatable integrally with the support member or relatively against the required frictional force. On the other hand, in a state in which the coil springs liberate the outer ring, the support member is disconnected from the outer ring and becomes rotatable with a sufficiently small force with respect to the outer ring, and the inner ring also becomes rotatable with a sufficiently small force with respect to the support member. In other words, in the torque hinge of the present invention, it is possible to switch between a state for rotating two members connected to both the sides integrally or relatively against the required frictional force by performing the required operation; and a state for relatively rotating the members with a sufficiently small force without depending on a required frictional force. Therefore, if the torque hinge of the present invention is assembled as a rotation transmitter in a door of a vehicle for instance, and the inner ring and the support member are connected to the electric motor and to the door respectively, the electric motor is capable of opening and closing the door against the required frictional force applied by the connection member in a state in which the coil springs retain the outer ring. The door may be subjected suddenly to an external force by wind or the like when the door is in an opening/closing operation by the driving torque of the electric motor or when the door is retained at the full-open position or the intermediate open position by the detent torque or the retaining torque of the electric motor. In such a case, the external force applied to the door can be released by the relative rotation of the inner ring and the outer ring, thereby preventing flapping of the door. On the other hand, in a state in which the coil springs liberate the outer ring, the door can be opened and closed with a sufficient small force even if the inner ring is connected to the electric motor.

A further detailed explanation will be made below with reference to the accompanying drawings that show a preferred embodiment of a torque hinge configured in accordance with the present invention.

The following explanation will be made by referring to <FIG>, mainly <FIG>. A torque hinge denoted generally as numeral <NUM> has an inner ring <NUM> and outer ring <NUM> that have a common rotation axis o1, and a connection member <NUM>.

The following explanation will be made by referring to <FIG> and also <FIG>. The inner ring <NUM> is made of metal and it has a substantially cylindrical shape. The axial central portion of the inner ring <NUM> is provided with a working portion <NUM> having a peripheral surface with a circular cross section and a comparatively large diameter. At the axial both sides of the working portion <NUM>, inner ring shaft portions <NUM> each having a comparatively small diameter and a peripheral surface with a circular cross section are provided. At the axial free end parts of one of the two inner ring shaft portions <NUM>, U-shaped notches <NUM> are formed. The notches <NUM> are formed at the diametrical both sides of the inner ring shaft portion <NUM>. The inner ring <NUM> may be connected via the notches <NUM> to the shaft member s at the driving side shown by a two-dot chain line in <FIG> and <FIG> or the like.

The following explanation will be made by referring to <FIG> and also <FIG>. The outer ring <NUM> is made of metal and it has a substantially cylindrical shape. As can be understood by referring to <FIG> and <FIG>, the inner diameter of the outer ring <NUM> is larger than the outer diameter of the working portion <NUM> of the inner ring <NUM>, and the outer ring <NUM> is disposed outside the inner ring <NUM> in a state including the inner ring <NUM>. While the cross-sectional shape of the outer peripheral surface of the outer ring <NUM> is circular, six circumferential locking ridges <NUM> are provided circumferentially at equal angular intervals on the inner peripheral surface, and the circumferential locking ridges <NUM> are formed by locally reducing the inner diameter. The circumferential locking ridges <NUM> extend linearly in the axial direction over the outer ring <NUM>, and its cross-sectional shape is substantially rectangular.

As shown in <FIG> and <FIG>, the connection member <NUM> is disposed between the inner ring <NUM> and the outer ring <NUM>, and more specifically between the outer peripheral surface of the inner ring <NUM> and the inner peripheral surface of the outer ring <NUM>. The following explanation will be made by referring to <FIG> and also <FIG>. In the illustrated embodiment, the connection member <NUM> is made of metal, and it has a connection base portion <NUM> shaped as a substantially annular thin plate. As shown in <FIG> and <FIG>, the connection base portion <NUM> is disposed perpendicularly to the common rotation axis o1 by surrounding the outer peripheral surface of the inner ring <NUM>. The outer peripheral edge of the connection base portion <NUM> is provided with an annularly-shaped outer peripheral reinforcing portion <NUM> that stands in the axial direction and bends radially outward. At the inner peripheral edge portion of the connection base portion <NUM>, six engaging recesses <NUM> that are substantially rectangular are formed at equal angular intervals in the circumferential direction. The engaging recesses <NUM> are formed by locally increasing the inner diameter of the connection base portion <NUM>. The inner peripheral edge of the angular region at the connection base portion <NUM>, where the engaging recesses <NUM> are not formed, are bent in the axial direction to form spring portions <NUM>. As shown in <FIG>, the spring portions <NUM> elastically come into close contact with the outer peripheral surface of the working portion <NUM> of the inner ring <NUM>. As will be understood by referring to the enlarged view of the portion B of <FIG>, the spring portions <NUM> are bent to the same side as the outer peripheral reinforcing portion <NUM> in the axial direction.

The aforementioned connection member <NUM> connects disconnectably the inner ring <NUM> and the outer ring <NUM> by the required frictional force. In the illustrated embodiment, the connection member <NUM> is retained from the axial both sides by a pair of retainers <NUM> and <NUM> made of a synthetic resin, and each of the pair of retainers <NUM> and <NUM> is locked to the outer ring <NUM> in the circumferential direction by the circumferential locking means described later. That is, the connection member <NUM> is assembled with the outer ring <NUM> in a non-rotatable manner with respect to the outer ring <NUM>. The following explanation will be made by referring also to <FIG>. The pair of retainers <NUM> and <NUM> are of mutually corresponding shape and both have retainer base portions <NUM> each shaped as an annular plate. As shown in <FIG> and <FIG>, the retainer base portions <NUM> also are disposed perpendicular to the common rotation axis o1, surrounding the outer peripheral surface of the inner ring <NUM>. At the outer peripheral edge portion of a retainer base portion <NUM>, six circumferential locking recesses <NUM> of a substantially rectangular shape are provided at equal angular intervals in the circumferential direction. The circumferential locking recesses <NUM> are formed by locally reducing the outer diameter of the retainer base portion <NUM>. As shown in <FIG>, the circumferential locking recesses <NUM> correspond to the circumferential locking ridges <NUM> formed on the outer ring <NUM>, thereby constituting the circumferential locking means as described above. On the retainer base portion <NUM>, an inner ring axial bearing surface <NUM> of annular shape is formed by reducing the axial width along the inner peripheral edge. As shown in <FIG> and <FIG>, the inner ring axial bearing surface <NUM> supports in the axial direction the working portion <NUM> of the inner ring <NUM>. In the retainer base portion <NUM> of the retainer <NUM>, six engaging convex columns <NUM> extending linearly in the axial direction are provided at equal angular intervals in the circumferential direction along the outer peripheral edge of the inner ring axial bearing surface <NUM>. In the retainer base portion <NUM> of the retainer <NUM>, six engaging depressions <NUM>, which are depressed in the axial direction, are provided at equal angular intervals in the circumferential direction along the outer peripheral edge of the inner ring axial bearing surface <NUM>. Further, the engaging depressions <NUM> are provided with minute stepped portions 42a extending continuously in the circumferential direction along the outer peripheral edge. The respective cross-sectional shapes of the engaging convex columns <NUM>, the engaging depressions <NUM> and the engaging recesses <NUM> (formed in the connection member <NUM>) correspond to each other.

In the illustrated embodiment, a plurality of the connection members <NUM> (three in the illustrated embodiment) are disposed by stacking in series in the axial direction. The circumferential angular positions of the respective engaging recesses <NUM> of the plurality of connection members <NUM> and the circumferential angular positions of the respective spring portions <NUM> are matched with each other. The pair of retainers <NUM> and <NUM> are disposed on the axial both sides of the entire plurality of connection members <NUM> disposed by stacking in series in the axial direction. The tip portions of the engaging convex columns <NUM> of the retainer <NUM> are fitted into the engaging depressions <NUM> of the retainer <NUM> after passing through the engaging recesses <NUM> of the connection members <NUM> in the axial direction. In this manner, the plurality of connection members <NUM> disposed by stacking in series in the axial direction are entirely retained from the axial both sides by the pair of retainer <NUM> and retainer <NUM>. The thus assembled connection members <NUM> and the pair of retainers <NUM> and <NUM> are advanced into the outer ring <NUM> after matching the circumferential locking recesses <NUM> formed on the pair of retainers <NUM> and <NUM> and the circumferential locking ridges <NUM> formed on the inner peripheral surface of the outer ring <NUM> (see also <FIG>). In this manner, the connection members <NUM> are mounted in a non-rotatable manner with respect to the outer ring <NUM> via the pair of retainers <NUM> and <NUM>. If desired, by forming circumferential locking recesses on the outer peripheral surfaces of the connection members <NUM>, it is also possible to mount directly the connection members on the inner peripheral surface of the outer ring <NUM> without using the pair of retainers <NUM> and <NUM>.

As shown in <FIG> and <FIG>, the outer ring <NUM> is inserted into the cylindrical support member <NUM> and supported thereby. As explained with reference to <FIG> together with <FIG>, the support member <NUM> is formed of a synthetic resin by an appropriate molding method, and it has an annularly shaped support base portion <NUM>. The support base portion <NUM> has a constant radial width except for the circumferential required part. On the axial both side surfaces of the support base portion <NUM>, a wound portion axial bearing surface <NUM> and a hook groove <NUM> are formed respectively. The annular wound portion axial bearing surface <NUM> is formed by reducing the axial width from both the sides along the inner peripheral edge of the support base portion <NUM>, and the hook groove <NUM> linearly extends radially outward from the wound portion axial bearing surface <NUM>. As shown in <FIG>, the wound portion axial bearing surface <NUM> and the hook groove <NUM> bear the wound portions <NUM> and the hook portions <NUM> of the coil springs <NUM> to be described later, respectively. A support outer peripheral wall <NUM> of substantially arcuate shape extending continuously in the circumferential direction is formed on the outer peripheral surface of the support base portion <NUM> except for the required angular part. At the circumferential angular position of the support outer peripheral wall <NUM> where the hook groove <NUM> is formed, a gap <NUM> penetrating in the radial direction is formed on the side where the hook groove <NUM> is formed in the axial direction (see <FIG>). A pair of ear portions <NUM> extending radially outward are formed on the diametrical both sides of the outer peripheral surface of the support outer peripheral wall <NUM>. A fixing hole <NUM> penetrating in the axial direction is formed in the center of each of the pair of ear portions <NUM>. By inserting a fixing device (not shown) such as a bolt into the fixing hole <NUM>, the support member <NUM> can be fixed to the driven-side member (not shown) such as a door of a vehicle. Locking ridges <NUM> extending in the circumferential direction are formed at the axial both side end portions on the inner peripheral surface of the support outer peripheral wall <NUM>.

A support shaft <NUM> extending in the radial direction is provided at the circumferential central position on the outer peripheral surface of the required angular part of the support base portion <NUM>. In the illustrated embodiment, while the support shaft <NUM> is cylindrical as a whole, slits <NUM> penetrating in the diametrical direction (of the support shaft <NUM>) are formed from the free end to the fixation end portion, and the free end portion is elastically deformable. Further, a locking projection <NUM> projecting radially outward (of the support shaft <NUM>) is provided at the free end portion of the support shaft <NUM>. As shown in <FIG> and <FIG>, the support shaft <NUM> is assembled with an intermediate member <NUM> rotatable about the support shaft <NUM>.

The following explanation will be made by referring also to <FIG>. The intermediate member <NUM> is formed of a synthetic resin by an appropriate molding method, and it has a bevel gear <NUM> and a spur gear <NUM> that rotate integrally about the support shaft <NUM>. The bevel gear <NUM> and the spur gear <NUM> have a common central axis o2. An outer end of the bevel gear <NUM> extends linearly in the axial direction and is connected to a side surface of the spur gear <NUM>. At the center of the intermediate member <NUM>, a support shaft hole <NUM> extending linearly in the axial direction of the common central axis o2 is formed. At the axial end portion in the support shaft hole <NUM> facing the spur gear <NUM>, a locking stepped portion <NUM> formed by locally enlarging the diameter is provided. As shown in <FIG>, the intermediate member <NUM> is assembled rotatably with respect to the support shaft <NUM>, since the support shaft <NUM> is inserted from the bevel gear <NUM> side of the support shaft hole <NUM>, the locking projections <NUM> of the support shaft <NUM> pass through the locking stepped portion <NUM> provided in the support shaft hole <NUM> of the intermediate member <NUM>, thereby elastically locking thereof. In the illustrated embodiment, the spur gear <NUM> is connected to an operation mechanism (not shown). The intermediate member <NUM> is driven to rotate about the support shaft <NUM> by an operation of the operation mechanism.

The following explanation will be made by referring to <FIG>. Two control members <NUM> for controlling the coil springs <NUM> described later are assembled in series in the axial direction with the support member <NUM>. In the illustrated embodiment, the control members <NUM> are disposed one on each axial side of the support member <NUM>. When reference is made to each of the two control members <NUM>, 'a' or 'b' is suffixed for distinguishment thereof. The following explanation will be made by referring to <FIG> and also <FIG>. The control members <NUM> each is formed of a synthetic resin by an appropriate molding method, and it has a substantially circular control base plate <NUM> arranged perpendicularly to the common rotational shaft o1. A circular through hole <NUM> is formed in the center of the control base plate <NUM>. The control base plate <NUM> is provided with a cylindrical support protrusion <NUM> that extends in the axial direction by surrounding the outer peripheral edge of the through hole <NUM> and an annular outer ring bearing groove <NUM> that surrounds the fixation end portions of the support protrusions <NUM>. When the control members <NUM> are assembled with the support member <NUM> as described later, as shown in <FIG> and <FIG>, the free end portion of the support protrusion <NUM> enters between the inner peripheral surface of the outer ring <NUM> and the outer peripheral surface of the inner ring <NUM> (more specifically, the inner ring shaft portion <NUM>), whereby the connection member <NUM> and the pair of retainers <NUM> and <NUM> for retaining the same are supported from the axial both sides by the support protrusions <NUM> of the control members 72a and 72b disposed on the axial both sides of the support member <NUM>. Further at this time, the inner ring <NUM> is rotatably supported by the support protrusions <NUM>, while the axial end portion of the outer ring <NUM> is rotatably supported by the outer ring bearing groove <NUM>. A substantially cylindrical control outer peripheral wall <NUM> extending in the axial direction parallel to the support projections <NUM> is also formed on the outer peripheral edge portion of the control base plate <NUM>. Hook grooves <NUM> penetrating through the radial direction and extending linearly in the axial direction are formed at a specific angular part of the control outer peripheral wall <NUM>. The hook grooves <NUM> extend over the control peripheral wall <NUM> in the axial direction. In the specific angular region indicated with a reference numeral <NUM> on the control outer peripheral wall <NUM>, the outer diameter is slightly reduced, and arcuate racks <NUM> extending in the circumferential direction are provided on the axial free end surface. The specific angular regions <NUM> are provided one on each diametric side. As shown in <FIG> and <FIG>, since the racks <NUM> engage the bevel gear <NUM> of the intermediate member <NUM>, the racks <NUM> preferably extend in the circumferential direction along the required conical surface corresponding to the conical surface on which the teeth of the bevel gear <NUM> are formed. Even in the free end portion of the angular region other than the specific angular region <NUM> on the control outer peripheral wall <NUM>, the outer diameter is slightly reduced, and arcuate lock ridges <NUM> extending in the circumferential direction are formed on the outer peripheral surface.

As shown in <FIG>, the lock ridges <NUM> elastically rides over the engaging ridges <NUM> of the support member <NUM> so as to be locked therewith in the axial direction, whereby the control members <NUM> are assembled with the support member <NUM>. In a state in which the control members <NUM> are assembled with the support member <NUM>, the control members <NUM> are rotatable about a common rotation axis o1 with respect to the support member <NUM>. Further in this state, as described above, the racks <NUM> of the control members <NUM> mesh with the bevel gear <NUM> of the intermediate member <NUM> assembled with the support shaft <NUM> of the support member <NUM>. In the illustrated embodiment, the two control members 72a and 72b are arranged one on each axial side of the support member <NUM>. Therefore, the racks <NUM> formed on each of these two control members 72a and 72b are interconnected via the bevel gear <NUM>, so that the two control members 72a and 72b each and the intermediate member <NUM> are interlocked. Therefore, if the intermediate member <NUM> rotates about the support shaft <NUM> counterclockwise in the front view of the same drawing, as it is understood by also referring to <FIG> and <FIG>, due to the meshing between the bevel gear <NUM> of the intermediate member <NUM> and the respective racks <NUM> of the two control members 72a and 72b, the control member 72a located on the left side in the central front view of <FIG> rotates clockwise (viewed from the left side of the same drawing) about the common rotation axis o1, while the control member 72b located on the right side in <FIG> rotates counterclockwise about the common rotation axis o1 (viewed from the same left side), namely, the rotational directions of the two control members 72a and 72b are reversed to each other. This will be described further below.

As shown in <FIG> and <FIG>, coil springs <NUM> are mounted on the outer peripheral surface of the outer ring <NUM>. In the illustrated embodiment, the coil springs <NUM> are disposed one on each axial side of the support member <NUM>. When referring to each of the two coil springs <NUM>, 'a' or 'b' is suffixed for distinguishment thereof. The following explanation will be made by referring to <FIG> together with <FIG>. The coil springs <NUM> each has a wound portion <NUM> formed by spirally winding a metal wire having a rectangular cross section, and a pair of hook portions <NUM> formed by bending the wire radially outward at both axial ends of the wound portion <NUM>. The inner diameter of the wound portion <NUM> is smaller than the outer diameter of the outer ring <NUM> when the coil spring <NUM> is in a free state, and the coil spring <NUM> is mounted on the outer peripheral surface of the outer ring <NUM> in a state in which the inner diameter of the wound portion <NUM> is temporarily expanded. As will be understood by comparing and referring to <FIG> and <FIG>, when the coil spring <NUM> is in a free state, each of the pair of hook portions <NUM> is located at an angular interval of approximately <NUM> degrees. In a state shown in <FIG> (i.e., the state in which the intermediate member <NUM> is not operated by an operation mechanism that is not shown, as will be described later), each of the pair of hook portions <NUM> is located at an angular interval of approximately <NUM> degrees. Therefore, in a state in which the coil spring <NUM> is mounted on the outer peripheral surface of the outer ring <NUM> and no force is applied to the pair of hook portions <NUM>, the inner peripheral surface of the wound portion <NUM> is in close contact with the outer peripheral surface of the outer ring <NUM>, and the coil springs <NUM> tighten the outer peripheral surface of the outer ring <NUM> to retain it. In the illustrated embodiment, two coil springs 89a and 89b are disposed one on each axial side of the support member <NUM>. After the outer ring <NUM> is inserted into the support member <NUM> and before the control member <NUM> is assembled with the support member <NUM>, the two coil springs 89a and 89b are mounted on the outer ring <NUM> one from each axial side, and the pair of hook portions <NUM> each is fitted into each of the hook grooves <NUM> and <NUM> formed on the support member <NUM> and on the control member <NUM>. At this time, for instance, the winding direction of the wires constituting the two coil springs 89a and 89b may be reversed to each other when viewed from one end in the axial direction. The reason will be described later.

Next, the actions of the torque hinge <NUM> will be explained. In the state as shown in <FIG>, the operation mechanism (not shown), which is connected to the spur gear <NUM> of the intermediate member <NUM> in order to rotate and drive the member <NUM>, is not actuated. Therefore, each of the two coil springs 89a and 89b arranged on the axial both sides of the support member <NUM> tightens and retains the outer peripheral surface of the outer ring <NUM>. When the rotation torque is applied from the shaft member s to the inner ring <NUM> in this state, the inner ring <NUM> and the support member <NUM> rotate integrally since the inner ring <NUM> is connected to the outer ring <NUM> by the required frictional force applied by the connection member <NUM>. Alternatively, the inner ring <NUM> and the support member <NUM> rotate relatively since the inner ring <NUM> slides with respect to the outer ring <NUM> against the required frictional force applied by the connection member <NUM>.

When rotation torque is applied to the inner ring <NUM>, the outer ring <NUM> connected to the inner ring <NUM> by the connection member <NUM> tries to rotate in the same direction as the rotation direction of the inner ring <NUM>. In the illustrated embodiment, the winding direction of the wires constituting the two coil springs 89a and 89b arranged on the axial both sides of the support member <NUM> are opposite to each other when viewed from one end in the axial direction. Therefore, when the inner ring <NUM> rotates clockwise when viewed from the left side in <FIG> and <FIG> for instance, as can be understood by referring also to <FIG>, one of the pair of hook portions <NUM> of the coil spring 89a mounted on the outer ring <NUM>, namely, a hook portion <NUM> that is fitted into the hook groove <NUM> formed in the support member <NUM>, is pressed by the support member <NUM> in the direction to loosen the spring, in the hook groove <NUM> formed in the support member <NUM>. On the other hand, the other hook portion <NUM> of the coil spring 89b mounted on the outer ring <NUM>, namely, the hook portion <NUM> fitted into the hook groove <NUM> formed on the support member <NUM>, is pressed by the support member <NUM> in the direction to tighten the spring in the hook groove <NUM> formed on the support member <NUM>. If the inner ring <NUM> rotates in the opposite direction, the situation is reversed. That is, regardless of the rotational direction of the inner ring <NUM>, since either one of the hook portions <NUM> of the two coil springs 89a and 89b is pressed in a direction to tighten the spring at all times, the outer ring <NUM> is sufficiently reliably retained by the coil spring <NUM>. As a result, in a case where a single coil spring <NUM> is mounted on the outer peripheral surface of the outer ring <NUM>, or in a case where two coil springs <NUM> whose winding directions of the wires are the same when viewed from one end in the axial direction are mounted on the outer peripheral surface of the outer ring <NUM>, when the outer ring <NUM> tries to rotate in the same direction as the rotation direction of the inner ring <NUM> by the rotation torque applied to the inner ring <NUM>, even if any one of the pair of hook portions <NUM> of the coil springs <NUM> is pressed by the support member <NUM> in the direction for loosening the spring, it is necessary to limit the magnitude of the input torque in the range for allowing the coil spring <NUM> to retain the outer ring <NUM>.

When the intermediate member <NUM> is driven to rotate counterclockwise about the support shaft <NUM> in the central front view of <FIG> by an operation mechanism (not shown) from the state shown in <FIG>, the control member <NUM> equipped with the racks <NUM> meshing with the bevel gear <NUM> of the intermediate member <NUM> rotates about the common rotation axis o1 with respect to the support member <NUM>, and presses the hook portions <NUM> of a coil spring <NUM> fitted into the hook grooves <NUM> of the control member <NUM> in a direction to loosen the coil spring <NUM>. In the illustrated embodiment, both the control members <NUM> and the coil springs <NUM> are arranged one on each axial side of the support member <NUM>. The wires constituting the two coil springs 89a and 89b arranged on the axial both sides of the support member <NUM> are wound in the directions opposite to each other when viewed from one end in the axial direction. Since the two control members 72a and 72b rotate in the directions opposite to each other as mentioned above, the hook portions <NUM> of the two coil springs 89a and 89b are pressed at the same time in the direction to loosen the coil springs <NUM>. <FIG> shows a state in which the intermediate member <NUM> is stopped after being rotated by the required angle counterclockwise by the operation mechanism. The intermediate member <NUM> is retained by the operation mechanism in the angular position shown in <FIG>. As will be appreciated by comparing and referring to the left view of <FIG> with the left view of <FIG>, the control member 72a is rotated clockwise about the common rotation axis o1 in the left views. Meanwhile, as will be appreciated by comparing and referring to the right view of <FIG> and the right view of <FIG>, the control member 72b is also rotated clockwise about the common rotation axis o1 in the right views. The rotational directions of the control members 72a and 72b in the drawings are the same, but as described above, their rotational directions are opposite to each other when viewed from one end in the axial direction. In the state shown in <FIG>, as shown in <FIG>, the coil springs 89a and 89b liberate the outer ring <NUM>, and the outer ring <NUM> is rotatable with respect to the coil springs 89a and 89b. That is, in a case where the rotational torque is applied around the common rotation axis o1 to the support member <NUM>, since the support member <NUM> (and the control member 72a and 72b to be assembled therewith) is rotatable with respect to the outer ring <NUM>, the inner ring <NUM> and the support member <NUM> are relatively rotatable regardless of the required frictional force applied by the connection member <NUM>. In <FIG>, the inner peripheral surface of the wound portions <NUM> of the coil springs 89a and 89b are completely separated from the outer peripheral surface of the outer ring <NUM>. However, if the outer ring <NUM> is rotatable with respect to the coil springs 89a and 89b, the inner peripheral surfaces of the wound portions <NUM> of the coil springs 89a and 89b may not necessarily be completely separated from the outer peripheral surface of the outer ring <NUM>, respectively. Both the surfaces may be in contact with each other.

As for the torque hinge of the present invention, the pair of hook portions <NUM> of each coil spring <NUM> mounted on the outer peripheral surface of the outer ring <NUM> are fitted into the hook grooves <NUM> and <NUM> formed respectively in the support member <NUM> for supporting the outer ring <NUM> and the control members <NUM> assembled with the support member <NUM> in series in the axial direction. The control members <NUM> are rotatable about a common rotation axis o1 of the inner ring <NUM> and the outer ring <NUM> with respect to the support member <NUM>. Therefore, by relatively rotating the support member <NUM> and the control members <NUM> about the common rotation axis o1, it is possible to switch between a state in which the coil springs <NUM> tighten and retain the outer ring <NUM>, and a state in which the coil springs <NUM> liberate the outer ring <NUM>.

Therefore, in a state in which the coil springs <NUM> tighten and retain the outer ring <NUM>, the support member <NUM> is integrated with the outer ring <NUM>. As a result, the inner ring <NUM> connected to the outer ring <NUM> by the required frictional force applied by the connection member <NUM> becomes rotatable with the support member <NUM> integrally or relatively against the required frictional force. On the other hand, in a state in which the coil springs <NUM> liberate the outer ring <NUM>, the support member <NUM> is separated from the outer ring <NUM> and becomes rotatable with respect thereto with a sufficiently small force, and thus, the inner ring <NUM> becomes also rotatable with respect to the support member <NUM> with a sufficiently small force. In other words, by using the torque hinge of the present invention, it is possible to switch between states, i.e., a state of rotating two members connected to both the sides integrally or relatively against the required frictional force by performing a required operation, and a state of relatively rotating with a sufficiently small force without depending on the required frictional force. Therefore, if the torque hinge of the present invention is assembled in a vehicle door for instance as a rotation transmitter while the inner ring <NUM> and the support member <NUM> are connected to the electric motor and the door respectively, the electric motor is capable of opening/closing the door against the required frictional force by the connection member <NUM> in a state in which the coil springs <NUM> retain the outer ring <NUM>. In the meantime, the door may be subjected suddenly to an external force by wind or the like when the door is in an opening/closing operation by the driving torque of the electric motor or when the door is retained at the full-open position or the intermediate open position by the detent torque or the retaining torque of the electric motor. In such a case, the external force applied to the door can be released by the relative rotation of the inner ring <NUM> and the outer ring <NUM>, thereby preventing flapping of the door. On the other hand, in a state in which the coil springs <NUM> liberate the outer ring <NUM>, the door can be opened and closed with a sufficient small force even if the inner ring <NUM> is connected to the electric motor.

Claim 1:
A torque hinge (<NUM>) comprising an inner ring (<NUM>) and an outer ring (<NUM>) that have a common rotation axis, and a connection member (<NUM>) disposed between the inner ring and the outer ring so as to connect disconnectably the inner ring and the outer ring by a required frictional force, the inner ring and the outer ring are rotatable integrally or relatively against the required frictional force,
the outer ring (<NUM>) is inserted into a cylindrical support member (<NUM>) so as to be supported by the support member, and coil springs (<NUM>) having a pair of hook portions (<NUM>) are mounted on the outer peripheral surface of the outer ring,
a control member (<NUM>) for controlling the coil springs (<NUM>) is assembled in series in an axial direction with the support member, the control member is rotatable about the common rotation axis with respect to the support member, and the support member and the control member each has hook grooves (<NUM>, <NUM>) into which each of the pair of hook portions (<NUM>) of the coil spring is to be fitted, and
the coil spring retains or liberate the outer ring (<NUM>) by a required operation.