Opening and closing device

An opening and closing device for moving a movable member which includes a drive gear connected to a power source, a driven gear geared with the drive gear, an immovable portion supporting the drive gear and the driven gear, and a dynamic transmission mechanism connected to the driven gear so that the driven gear and the dynamic transmission mechanism rotate together as a unit. The dynamic transmission mechanism transmits a drive force of the power source from the driven gear to the movable member. A direction of a rotational force affecting the driven gear via the dynamic transmission mechanism in accordance with a state of the movable member fluctuates. The opening and closing device further includes a friction member located at least at one position between relatively movable facing surfaces of the immovable portion, the drive gear, the driven gear, and the dynamic power transmission mechanism.

This application is based on and claims priority under 35 U.S.C. § 119 with respect to Japanese Patent Application No. 2002-122157 filed on Apr. 24, 2002, the entire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention generally relates to an opening and closing device. More particularly, the present invention pertains to an opening and closing device associated with a movable member (e.g., a vehicle door) for moving the movable member (e.g., opening and closing the vehicle door) using a gear actuation.

BACKGROUND OF THE INVENTION

A known opening and closing device for a movable member (opening and closing body) is disclosed in Japanese Patent Laid-Open Publication No. 2000-335245. The known opening and closing device disclosed in Japanese Patent Laid-Open Publication No. 2000-335245 is applied to a backdoor provided on a rear portion of a vehicle as the opening and closing device of the movable member.

The opening and closing device disclosed in Japanese Patent Laid-Open Publication No. 2000-335245 includes a drive mechanism provided on a vehicle body side and an operation transmission mechanism for connecting the drive mechanism and the backdoor. The backdoor is opened and closed by transmitting the drive force of the drive mechanism to the backdoor via the operation transmission mechanism. The output of an electric motor included in the drive mechanism is transmitted to the operation transmission mechanism by the gear connection.

The opening and closing of the backdoor is generally assisted by a damper stay. The damper stay corresponds to a gas piston sealed with high pressure gas. The damper stay generates a resultant force in the closing direction added with the weight of the backdoor per se during the first half of the operation for opening the backdoor to prevent the sudden door opening. On the other hand, the damper stay assists to open the door by generating the resultant force in the opening direction added with the weight of the backdoor per se during the last half of the operation for opening the backdoor.

FIGS. 9a,9bshow the dynamic transmission between a drive gear (i.e., a gear on a motor side)91and a driven gear (i.e., a gear on a door side)92of the drive mechanism.FIG. 9ashows the first half of the door opening operation.FIG. 9bshows the last half of the door opening operation. For explanatory purpose, distances between adjacent gear teeth91aof the drive gear91and distances between adjacent gear teeth92aof the driven gear92are exaggerated. As shown inFIG. 9a, a force is applied to the driven gear92tending to urge the driven gear92in the counter direction to the rotational direction of the drive gear91during the first half of the door opening operation of the backdoor because the backdoor affecting the driven gear92applies a force in the closing direction during the first half of the door opening operation. Thus, the driven gear92follows the rotation of the drive gear91pushing the gear teeth92aof the driven gear92with the gear teeth91athereof. Accordingly, the backdoor is moved in the opening direction via the driven gear92.

On the other hand, as shown inFIG. 9b, during the last half of the door opening operation, when the backdoor is moved to a position exceeding a position balancing the force of the damper stay and the weight of the backdoor per se, the backdoor applies a force in the opening direction to urge the driven gear92in the same rotational direction as the drive gear91. Because of the fluctuation in the rotational direction of the force applied to the driven gear92by virtue of the weight of the backdoor at the damper stay, the driven gear92moves within a backlash range relative to the drive gear91to suddenly move the backdoor. This deteriorates the smooth swinging movement of the door opening operation.

A need thus exists for an opening and closing device of an movable member for performing a relatively smooth opening and closing operation by restraining undesirable sudden swinging movement of the movable member.

SUMMARY OF THE INVENTION

In light of the foregoing, the present invention provides an opening and closing device for moving a movable member which includes a drive gear connected to a power source, a driven gear geared with the drive gear, an immovable portion supporting the drive gear and the driven gear, and a dynamic transmission mechanism connected to the driven gear so that the driven gear and the dynamic transmission mechanism rotate together as a unit. The dynamic transmission mechanism transmits a drive force of the power source from the driven gear to the movable member. A direction of a rotational force affecting the driven gear via the dynamic transmission mechanism in accordance with a state of the movable member fluctuates. The opening and closing device further includes a friction member located at least at one position between relatively movable facing surfaces of the immovable portion, the drive gear, the driven gear, and the dynamic power transmission mechanism.

According to another aspect of the present invention, an opening and closing device for moving a movable member includes a drive gear connected to a power source, a driven gear geared with the drive gear, an immovable portion supporting the drive gear and the driven gear, a dynamic transmission mechanism, connected to the driven gear so that the driven gear and the dynamic transmission mechanism rotate together as a unit, the dynamic transmission mechanism transmitting a drive force of the power source from the driven gear to the movable member, and a shock absorbing member for applying a force to the movable member in accordance with a state of the movable member. A direction of a rotational force affecting the driven gear via the dynamic transmission mechanism in accordance with a resultant force from a weight of the movable member and the shock absorbing member fluctuates. The opening and closing device further includes a friction member applied at least at one position between relatively movable facing surfaces of the immovable portion, the drive gear, the driven gear, and the dynamic power transmission mechanism.

According to further aspect of the present invention, an opening and closing device for moving a movable member includes a drive gear connected to a power source, a driven gear geared with the drive gear, a housing supporting the drive gear and the driven gear, and an arm, connected to the driven gear so that the driven gear and the arm rotate together as a unit. The arm transmits a drive force of the power source from the driven gear to the movable member. A direction of a rotational force affecting the driven gear via the arm in accordance with a state of the movable member fluctuates. The opening and closing member further includes a friction member located at least at one position between relatively movable facing surfaces of the housing, the drive gear, the driven gear, and the arm.

DETAILED DESCRIPTION OF THE INVENTION

A first embodiment of an opening and closing device will be explained with respect to the drawing figures ofFIGS. 1–4. As shown inFIG. 4, an electric backdoor system1includes a backdoor3serving as a movable member connected to a top rear portion of a vehicle body2with a hinge, an actuator4for electrically opening and closing the backdoor3, and a damper stay5serving as a shock absorbing member.

The actuator4includes a drive unit11secured to a rear pillar2aof the vehicle body2, an arm12serving as a dynamic transmission mechanism connected to an output shaft of the drive unit11to be unitarily rotated, and a rod13for connecting a tip end portion of the arm12and a base end portion of the backdoor3. The rod13is connected to the tip end portion of the arm12and the base end portion of the backdoor3via a ball joint construction7(shown inFIG. 8) respectively so that the displacement is allowed while rotating.

Under the closed state of the backdoor3, the tip end side of the arm12is arranged to be positioned on a first side (i.e., bottom side ofFIG. 4). In accordance with this, the rod13is folded. On the other hand, under the state that the backdoor3is open, the arm12is rotated in one direction (i.e., counterclockwise direction ofFIG. 4) to position the tip end side of the arm12on a second side (i.e., right side ofFIG. 4). Accordingly, the rod13is pushed to support the backdoor3under the open state. By moving the arm12between the foregoing two states by driving the drive unit1, the backdoor3is opened and closed.

The damper stay5includes a gas piston injected with the high pressure gas. One end and the other end of the damper stay5are connected to the rear portion of the vehicle body2and the base end portion of the backdoor3respectively. The damper stay5generated the resultant force in the closing direction added with the weight of the backdoor3per se during the first half of the operation for opening the backdoor3to prevent the sudden door opening. On the other hand, the damper stay5assists to open the door by generating the resultant force in the opening direction along with the weight of the backdoor3per se during the last half of the opening operation of the backdoor3. In other words, the damper stay5adds the force either one of in the closing direction or the opening direction to the backdoor3with reference to the position balancing the generated force and the weight of the backdoor3per se. By the fluctuation of the force applied to the backdoor3, the rotational direction affecting the arm12and the drive unit11connected to the backdoor3via the rod13is fluctuated.

The configuration of the drive unit11and the arm12will be explained with reference toFIGS. 1–3. As shown inFIGS. 1–3, the drive unit11includes an electric motor21with decelerator serving as a drive source, a lower case22and an upper case23serving as an improvable portion (or a fixed housing), a motor side gear24, a drive gear25, a rotational shaft26, a driven gear27, and a rubber ring serving as a frictional member.

The electric motor21with the decelerator accommodates the decelerator including a worm and a worm wheel. An output shaft31of the electric motor21with a decelerator is projected on one side (i.e., top side ofFIG. 1). A serration31ais provided on the output shaft31.

The lower case22is configured being approximately stepped plate shape. The lower case22is formed with a bore22ato be inserted with the output shaft31. The lower case22is provided with the shaft potion22bprojected to one side (i.e., top side ofFIG. 1) corresponding to the drive gear25. Further, the lower case22is formed with a bearing bore22cformed corresponding to the rotation shaft26. The rotational shaft26is rotatably supported by the lower case22by being inserted into the bearing bore22c.

The motor side gear24is provided with a bore and is fitted on the output shaft31, so that the output shaft31passes through the bore. The motor side gear24is positioned in the inserting bore22aof the lower case22. A serration24ais formed on the internal peripheral surface of the bore in the motor side gear24and is adopted to engage the serration31aon the output shaft31. The motor side gear24is thus unitarily rotated with the output shaft31by virtue of the engagement of the serration24awith the serration31aof the output shaft31.

The drive gear25is rotataby supported by the lower case22via the shaft portion22bof the lower case22. The drive gear25includes a first gear portion25ahaving larger diameter than that of the motor side gear24and a second gear portion25bhaving a smaller diameter than that of the first gear portion25a. The first gear portion25aof the drive gear25is geared with the motor side gear24and thus the drive gear25is rotatably driven by the electric motor21with the decelerator.

The rotational shaft26is formed in approximately stepped pillar shape. A first shaft portion26aof the base end side (i.e., bottom side ofFIG. 1) is inserted into the bearing bore22cof the lower case22so that the rotational shaft26is rotatably supported by the lower case22. The rotation shaft26is configured to have steps whose diameters being reduced from the first shaft portion26ato a tip end side. The rotational shaft26includes a first serration shaft portion26b, a second shaft portion26c, a second serration shaft portion26d, and a screw portion26e. The driven gear27is secured to the first serration shaft portion26band the arm12is secured to the second serration shaft portion26d.

The driven gear27has a sector gear construction configured to have a portion of a circumference and is connected to the rotation shaft26for unitary rotating with the rotation shaft26. The driven gear27is formed with the penetration bore penetrated in the axial direction and an internal peripheral surface of the penetration bore is formed with a serration27acorresponding to the serration of the first serration shaft portion26b. Accordingly, the driven gear27is connected to the rotations shaft26to be unitary rotatable by securing the serration27ato the serration of the first serration shaft portion26b. The driven gear27is geared with the second gear portion25bof the drive gear25so that the driven gear27is rotated by the drive gear25along with the rotation shaft26.

The rubber ring28is configured to be approximately circular shape having an internal diameter larger than the internal diameter of the serration27aof the driven gear27. The rubber ring28is penetrated to be placed in approximately coaxial to the rotation shaft26surrounding the second shaft portion26cof the rotation shaft26projected to one side to be connected to the driven gear27. The rubber ring28is provided between the driven gear27and the uppercase23.

The upper case23is formed in the approximately stepped place shape. An inserting bore23abeing inserted with the tip end portion of the shaft portion22bpenetrating through the driven gear25is formed on the upper case23. Thus, the drive gear25is accommodated between the opposing surfaced between the lower case22and the upper case23and the movement of the drive gear25in the axial direction is restricted. The upper case23is provided with a bearing bore23bformed corresponding to a tip end portion of the second shaft portion26cinserted into the rubber ring28. The rotation shaft26is inserted into the bearing bore23bto be rotatably supported by the upper case23. Thus, the rotation shaft26is rotatably supported between the lower case22and the upper case23along with the driven gear27.

As shown inFIG. 2, the arm12is fitted through the shaft bore23bof the upper case23to be secured to the second serration shaft portion26dof the rotation shaft26projected to one side (i.e., top side ofFIG. 2) to be unitarily rotated with the rotation shaft26. More specifically, a sleeve12aprojected in the axial direction corresponding to the rotation shaft26(i.e., second serration shaft portion26d) is secured to the base portion of the arm12and a serration12bis formed in an internal peripheral surface of the sleeve12acorresponding to the serration of the second serration shaft portion26d. By fitting the serration12bto the serration of the rotation shaft26(i.e., the second serration shaft portion26d), the arm12is configured to be unitarily rotated with the rotation shaft26. A nut32is screwed on a screw portion26eof the rotation shaft26projected to the one side (i.e., top side ofFIG. 2) after fitting the arm12.

With the foregoing construction, when the output shaft31is rotated in one direction by supplying the power to the electric motor21with the decelerator, the rotation is transmitted to the arm12via the motor side gear24, the drive gear25(i.e., the first gear portion25aand the second gear portion25b), and the driven gear27. Thus, the rotation of the arm12is transmitted to the backdoor3via the rod13for moving the backdoor either in the opening direction or in the closing direction depending on the rotational direction of the arm12(shown inFIG. 4).

Provided that the direction of the rotational force urging the driven gear27via the arm12and the rod13in accordance with the resultant force of the force from the damper stay5and the weight of the backdoor3per se is fluctuated (shown inFIGS. 9a,9b). In this case, the drastic change of the urged rotational direction is restrained by the sliding resistance by the rubber ring28. In addition, because the movement of the driven gear27relative to the driven gear25within the range of the backlash is restrained, the undesirable sudden swinging movement due to the sudden movement of the backdoor3can be restrained.

According to the embodiment of the present invention, the rubber ring28is provided between the driven gear27and the upper case23. Thus, even when the direction of the urged rotational force affecting the driven gear27via the rod13and the arm12in accordance with the resultant force of the force of the damper stay5and the weight of the backdoor3is fluctuated, the sudden change of the urged rotational direction can be restrained by the sliding resistance of the rubber ring28. In addition, because the movement of the driven gear27relative to the drive gear25within the backlash range is restrained, the undesirable sudden swinging movement due to the sudden movement of the backdoor3can be restrained. Thus, the opening and closing operation of the backdoor3can be performed smoothly.

According to the embodiment of the present invention, the rubber ring28can be provided by using the existing housing (i.e., upper case23) for accommodating the driven gear27. Thus, the burden at design change can be mitigated.

According to the embodiment of the present invention, the rubber ring28is positioned approximately coaxial to the driven gear27. This absorbs the movement of the driven gear27in the axial direction.

According to the embodiment of the present invention, the movement within the range of the backlash can be swiftly performed during the initial stage by providing the rubber ring28for restraining the sudden change of the urged rotational direction in the drive unit11on a portion closest to a final deceleration portion of the drive unit11, that is, the loaded side (i.e., backdoor3). Embodiment is not limited to the above-explained embodiment and can be varied as follows.

With the first embodiment of the present invention, the rubber ring28is provided as the friction member. Instead of the rubber ring28, a wave washer41(serving as spring ring) may be provided as the friction member as shown inFIGS. 5–6. Although a plurality of (i.e., three) wave washers41are piled as shown inFIGS. 5–6, the number of the wave washers41is not limited to three as long as generating the favorable sliding resistance by the elastic force. In place of the wave washer41, a coned disc spring or a coil spring may be applied.

Although the annular shape friction member such as the rubber ring28and the wave washer41are applied in the foregoing embodiment, the configuration of the friction member is not limited to the annular shape. For example, a rubber plate serving as the friction member can be provided between the upper case23and the driven gear27.

According to the embodiment, the friction member such as the rubber ring28and the wave washer41is provided between the upper case23and the driven gear27. However, the friction member may be provided between the upper case23and the arm12. The rotational shaft26may be provided with a flange or the like opposing to the upper case23and the friction member may be provided between the flange or the like and the upper case23.

Although the friction member such as the rubber ring28and the wave washer41is provide between the upper case23and the driven gear27in the foregoing embodiment, the friction member may be provided between the lower case22and the driven gear27.

Although the rotation shaft26and the driven gear27are provided individually and the rotation shaft26and the driven gear27are connected in the foregoing embodiment, the rotation shaft26and the driven gear27may be formed as in one unit. By constructing the rotation shaft26and the driven gear27as one unit, the number of the parts is reduced in addition to obtaining other effects.

The position for applying the friction member such as the rubber ring28and the wave washer41is not limited to one and the optimal effect may be obtained by applying the frictional member at plural positions.

According to a third embodiment of the present invention, instead of the rubber ring28and the wave washer41serving as the friction member, high viscous grease may be applied as the friction member. By selecting high viscous grease with the low worked penetration degree defined in Japanese Industrial Standard (JIS) K2220 is equal to or less than 250 (i.e., the smaller degree number of the worked penetration indicates the higher viscosity), the better effect can be obtained. Because this method is applicable to the product without changing the parts, the manufacturing cost can be reduced.

As shown inFIG. 7, the high viscous grease may be applied to one of or a plurality of portions indicated as movable portions27b,25c,22d,31b.

A fourth embodiment of the present invention will be explained as follows. With the foregoing embodiments, the method for providing the friction member in the drive unit11or to the drive unit11and the arm12in order to solve the drawbacks that the swing is generated by the sudden movement of the backdoor at the changing portion of the load affecting deriving from the backlash between gears. Likewise, as explained from the transmission mechanism of the operation force from the drive unit11to the backdoor3, in case there is a play for the connection at the ball joint mechanism7for connecting the arm12and the rod13, the phenomenon that the backdoor is suddenly moved is generated. In order to solve the drawback, as shown inFIG. 8, a clearance72for pooling the grease is provided between a bearing portion13aof the ball joint mechanism7formed on the end portion of the rod13and a ball71fixed to the arm side. By sealing the high viscous grease into the clearance72, the sudden load change due to the play can be restrained. Further, by providing a shock absorbing member73to prevent the noise generated by the interference between the arm12and the rod13by the rotation of the rod13in the direction shown with an arrow a inFIG. 8, further favorable effect can be obtained.

Although the drive force of the drive unit11(i.e., driven gear27) is transmitted to the backdoor3via the arm12and the rod13in the foregoing embodiments, other constructions may be applied.

The construction of the electric motor21with the decelerator side for transmitting the dynamic to the drive gear25of the drive unit11is an example and other construction may be applied.

Although the embodiments of the present invention is applied to the electric backdoor system1, the embodiment of the present invention may be applied to a system for electrically opening and closing a gull wing door which upwardly flips the side doors of the vehicle.

Although the embodiment of the present invention is applied to the movable member (i.e., backdoor3) having the damper stay5, the damper stay5is not always necessary. For example, the direction of the rotation force affecting the driven gear27is changed depending on the relationship between the rotation range of the movable member and the gravity direction only by the weight of the movable member per se without the assist of the damper stay5. Accordingly, the same effects can be obtained even in this case.

Although the spring ring, the rubber ring, and the high viscous grease serving as the friction member are applied separately in the embodiments, any combination of the spring ring, the rubber ring, and the high viscous grease is applicable.

According to the embodiment of the present invention, the smooth opening and closing operation can be performed by restraining the swing of the movable member.

According to the embodiment of the present invention, the friction member can be applied using the existing hosing. Thus, the load for design change can be mitigated.

According to the embodiment of the present invention, by positioning the friction member coaxial to the driven gear, the vibration of the driven gear in the axial direction can be absorbed.