Seat swiveling device of a vehicle

A seat swiveling device of a vehicle comprises a stationary base, a movable base, a vehicle seat assembly and a swing lever. The movable base has a second pivot shaft for supporting the swing lever so that the swing lever is pivoted. The stationary base has a guide hole for defining a range in which the movable base is pivotable. The swing lever has an elongated hole in which the second pivot shaft is inserted and a locating lug which is guided along the guide hole. The guide hole has a recessed portion with which the locating lug is engaged by pivoting the swing lever thereby to fix the movable base to the stationary base at a predetermined position. The swing lever is movable relative to the second pivot shaft in accordance with the shape of the elongated hole.

BACKGROUND OF THE INVENTION

The present invention relates to a device for swiveling a vehicle seat in a horizontal plane.

The seat swiveling device for use in a vehicle is disclosed in Japanese Utility Model Application Publication No. 5-56582 and the Japanese Unexamined Patent Application Publication No. 10-109575. The latter shows a mechanism for adjusting the swiveling of the vehicle seat as a seat swiveling device for a vehicle.

Such an adjusting mechanism includes a lower base which is fixed to the floor of a vehicle compartment and has an annular support portion, an upper base which is slidably and pivotably mounted on the annular support portion of the lower base and has at its center an opening for fixing therein a vehicle seat assembly, and a holder which holds the upper base in such a way that the upper base is slidable relative to the annular support portion of the lower base. The holder has a cylindrical portion having formed therethrough plural holes which are arranged circumferentially in the cylindrical portion at a predetermined spaced intervals. A lock plate is pivotably mounted to the upper base by a pivot shaft. The lock plate has plural teeth which are engageable with holes in the holder.

In other words, the lock plate performs the function of making the upper base rotatable relative to the lower base or locked to the lower base so that the upper base is unrotatable relative to the lower base. The lock plate is mounted to the lower base by and pivoted about the pivot shaft which is provided on the lower base and has a circular cross section. For that reason, the lock plate has formed therein a shaft hole of a shape of a perfect circle having substantially the same diameter as the pivot shaft. In such an arrangement of the lock plate, therefore, the teeth are moved along a path of an arc centered on the pivot shaft. The teeth are formed in a direction that is substantially the same as the direction tangential to the above path of an arc, and the distance between the center of the pivot shaft and the lateral sides of the engaging teeth is constant.

According to the relative art, the shaft hole in the lock plate is of a perfect circle whose diameter corresponds to the diameter of the pivot shaft, and the distance between the center of the pivot shaft and the lateral sides of the teeth is constant. Therefore, the teeth tend to be engaged with the hole such that only one lateral side of the teeth contacts with one lateral side of the hole. For engaging the teeth and holes such that lateral sides of the teeth are in contact with the lateral sides of the hole with no gap therebetween, the shape of the hole has to correspond exactly to the shape of the teeth and the teeth and their holes have to be precisely positioned relative to each other. Thus, the teeth and the hole need to be formed with high accuracy and the teeth need to be accurately positioned with respect to the teeth in turning the vehicle seat assembly. In the conventional art, the engaging of the teeth of the swing lever cannot be brought into snug contact with the hole of the upper base with no gap therebetween by relatively easy operation.

Therefore, an object of the present invention is to provide a seat swiveling device in a vehicle which brings the teeth or a locating lug of the swing lever into contact with the hole of the upper base or a movable base with no gap therebetween while permitting relatively easy operation for the engagement.

SUMMARY OF THE INVENTION

In accordance with an aspect of the present invention, a seat swiveling device of a vehicle has a vehicle body. The seat swiveling device comprises a stationary base secured to the vehicle body, a movable base connected to the stationary base through a first pivot shaft, a vehicle seat assembly mounted on a top face of the movable base and a swing lever changing locking and unlocking positions of the movable base relative to the stationary base. The movable base has a second pivot shaft for supporting the swing lever so that the swing lever is pivoted. The stationary base has a guide hole for defining a range in which the movable base is pivotable. The swing lever has an elongated hole in which the second pivot shaft is inserted and a locating lug which is guided along the guide hole. The guide hole has a recessed portion with which the locating lug is engaged by pivoting the swing lever thereby to fix the movable base to the stationary base at a predetermined position. The swing lever is movable relative to the second pivot shaft in accordance with the shape of the elongated hole.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The following will describe a seat swiveling device in a vehicle according to a preferred embodiment of the present invention with reference toFIGS. 1 through 6. The following description covers a seat swiveling device as applied to a forklift truck as an industrial vehicle.FIG. 1is a perspective view showing the seat swiveling device according to the preferred embodiment of the present invention.

Referring toFIG. 1, the seat swiveling device10for a vehicle has a stationary base11which is secured to the vehicle body and a movable base21which is held to the top face of the stationary base11by a pivot shaft13for pivoting about the pivot shaft13relative to the stationary base11. A vehicle seat assembly20is mounted on the top face of the movable base21so that the vehicle seat assembly20is swiveled or oriented in different directions as the movable base21is pivoted in a horizontal plane about the pivot shaft13.

The vehicle seat assembly20for a vehicle operator includes a seat20aand a backrest20b. The movable base21has a swing lever31that is operated by the operator on the vehicle seat assembly20for changing the movable base21between its locked and unlocked positions relative to the stationary base11. In unlocked position, the seat swiveling device of the vehicle10changes the direction of the vehicle seat assembly20by the operation of the swing lever31by the operator.

The following will describe each part of the seat swiveling device in detail. In the following description, the references to directions or locations such as front, rear, right, and left as viewed from a vehicle operator seated on the seat20aof the seat assembly20are used, as indicated inFIG. 1.

As shown inFIG. 2, the stationary base11is made of a bent metal plate having punched holes. The stationary base11has contact portions11aand11bwhich are formed by bending the opposite lateral end portions of the stationary base11along the longitudinal direction thereof. Fixing members12are provided in the front and rear portions of each of the contact portions11aand11bfor fixing the stationary base11to the vehicle body. The stationary base11has a horizontal portion11cwhich is formed between the opposite contact portions11aand11b. The horizontal portion11cis slightly raised from the contact portions11aand11b, and the top face of the horizontal portion11cis flat. The pivot shaft13is provided upstanding at the center on the top face of the horizontal portion11cadjacent to the front end thereof. The pivot shaft13pivotally holds the movable base21to function as a pivot for the movable base21.

Shafts14athrough14cwhich are similar to the pivot shaft13are provided on the top face of the horizontal portion11c. These shafts14athrough14care inserted in guide holes22through24, respectively, which are formed in the movable base21as shown inFIG. 1. As shown inFIG. 2, the shaft14ais provided adjacent to the contact portion11a, the shaft14badjacent to the contact portion11band the shaft14cadjacent to the rear edge of the horizontal portion11c, respectively.

A guide hole15is formed in the horizontal portion11cof the stationary base11which defines the range in which the movable base21is pivotable. The guide hole15received therein a locating lug34of the swing lever31and has an arcuate portion16and recessed portions17and18engageable with the locating lug34. The arcuate portion16is formed behind the pivot shaft13in the shape of a circular arc which is centered at the pivot shaft13. The recessed portions17and18of the guide hole15extend rearwardly from predetermined positions of the arcuate portion16. The arcuate portion16of the guide hole15limits the pivoting range of the movable base21, that is about 17 degrees in clockwise direction and about 25 degrees in counter-clockwise direction from the center position (which will be described later) of the movable base21as viewed in plan view ofFIG. 2.

The recessed portions17and18of the guide hole15are provided at the predetermined positions of the arcuate portion16in the form of cuts extending rearwardly. The recessed portions17and18of the preferred embodiment have the substantially same and complementary shape as the locating lug34. The recessed portion17is provided at such a position that the movable base21is located at the aforementioned center position where the seat assembly20faces straightforward when the locating lug34is engaged with the recessed portion17. The recessed portion18is provided at a position that is spaced by about 17 degrees in clockwise direction from the position of the recessed portion18. In other words, the recessed portion17serves to hold the movable base21at the center position, and the recessed portion18serves to hold the movable base21at the position that is spaced by 17 degrees in clockwise direction from the center position. The recessed portions17and18are wedge-shaped so that the widths of the recessed portions17and18are narrowed rearwardly or toward the ends thereof. The engagement of the locating lug34with the recessed portions17and18causes the movable base21to be fixed to the stationary base11.

The movable base21is a plate-like member connected to the stationary base11through the pivot shaft13. As shown inFIGS. 1 and 3, the movable base21of the preferred embodiment has a seat base portion21aon which the vehicle seat assembly20is to be mounted and lower portions21band21cwhich are formed lower than the seat base portion21a. As shown inFIG. 3, the lower portions21b,21care formed in the front and the rear of the movable base21, respectively. A shaft hole for receiving therethrough the pivot shaft13(not shown in the drawings) and guide holes22and23through which the shafts14aand14bare inserted are formed in the front of the lower portion21b(hereinafter referred to as “front lower portion”) of the movable base21. A guide hole24through which the shaft14cat the rear of the movable base21is inserted is formed in an arc-shape in the rear of the lower portion21c(hereinafter referred to as “rear lower portion”) of the movable base21.

The guide holes22through24in the front lower portion21band rear lower portion21care formed in the shape of arc of a circle whose center corresponds to the pivot shaft13. The lengths of the guide hole22through24are determined in accordance with the length of the guide hole15in the stationary base11which defines the pivoting range of the movable base21. With the movable base21connected to the stationary base11, retaining nuts are attached to the tops of the respective pivot shaft13and the shafts14athrough14c. A hole25is formed through the front lower portion21bfor receiving therein the locating lug34of the swing lever31, and a pivot shaft26is provided in the front lower portion21bfor pivotally supporting the swing lever31.

The through hole25defines the range in which the swing lever31is pivotable. According to the preferred embodiment, the through hole25is provided such that the position of engagement of the locating lug34with the recessed portions17and18and the arcuate portion16in the guide hole15is changed. A reinforcement plate27is attached to the movable base21at a position adjacent to the through hole25for preventing the deformation of the through hole25due to the engagement of the locating lug34with the hole25. The reinforcement plate27has formed a hole therethrough at a position corresponding to the hole25in the movable base21. The pivot shaft26supports the swing lever31and is located apart from the through hole25. According to the preferred embodiment, rollers28are mounted to the movable base21to provide smooth pivoting of the movable base21relative to the stationary base11.

The swing lever31is pivotally mounted to the movable base21through the pivot shaft26. As shown inFIG. 3, the swing lever31has a lever body32and a grip33. The lever body32is pivotally mounted on the pivot shaft26, and one end of the lever body32extends rightward out of the movable base21. The grip33is provided at a position of the end of the lever body32or one end of the swing lever31as a first end. The other end of the lever body32extends over the hole25and the locating lug34is provided at a position of the other end of the lever body32adjacent to the hole25. The locating lug34is inserted through the through hole25of the movable base21and further in the guide hole15of the stationary base11as shown inFIG. 4. The direction of the center axis of the locating lug34is substantially the same as the direction in which the swing lever31is pivoted, and the shape of the lateral sides of the locating lug34is substantially same as the shape of the lateral sides of the recessed portions17and18. By operating the grip33of the swing lever31, the locating lug34is fit into the recessed portions17and18or moved along the arcuate portion16of the guide hole15, thereby causing the movable base21to pivot in either leftward or rightward direction.

A coil spring35as an urging means is connected between the other end of the swing lever31as the second end and the movable base21for urging the locating lug34rearwardly or toward the recessed portions17or18. An elongated hole36as a shaft hole in which the pivot shaft26inserted is formed at a middle of the lever body32, and the longitudinal direction of the elongated hole36is the substantially same as the direction in which the locating lug34moves along the guide hole15. This allows the swing lever31to move for a distance corresponding to the clearance in the elongated hole36when the swing lever31is pivoted against the urging force of the coil spring35and the locating lug34is positioned at the arcuate portion16of the guide hole15. Providing the elongated hole36in the lever body32, operations of engaging or disengaging the locating lug34with or from the recessed portion17,18of the guide hole15by means of the swing lever31in moving the locating lug34in the guide hole15can be performed smoothly.

The following will describe the operation of the seat swiveling device of a vehicle according to the preferred embodiment. In the normal position of the vehicle seat assembly20in a forklift truck, as shown inFIG. 3, the movable base21is not pivoted relative to the stationary base11or the seat assembly20on the movable base21faces straightforward. In this position, the locating lug34of the swing lever31is secured in the recessed portion17and, therefore, the movement of the movable base21in the pivoting direction is restricted and the vehicle seat assembly20faces straightforward. In the normal position of the seat assembly20, the spring force of the coil spring35is applied to the swing lever31as a force in the direction in which the locating lug34is engaged with the recessed portion17. Thus, when the swing lever31is not operated, the locating lug34is kept engaged with the recessed portion17. The swing lever31may move relative to the pivot shaft26for a distance corresponding to the clearance in the elongated hole36. The recessed portion17is wedge-shaped with its width narrowed toward its bottom, so that the locating lug34contacts with recessed portion17with no gap therebetween.

The following will describe the case when the direction of the vehicle seat assembly20is changed. When the vehicle seat assembly20is pivoted clockwise direction as viewed, for example, inFIG. 3, the operator's body is turned rightward and this is convenient for the operator to check for the rear of the vehicle body when the forklift truck is driven backward. For disengagement the locating lug34from the recessed portion17, the swing lever31is operated such that the locating lug34which is then engaged with the recessed portion17is moved toward the arcuate portion16. According to the preferred embodiment, for disengaging the locating lug34from the recessed portion17, the grip33is moved backward so that the swing lever31is pivoted against the urging force of the coil spring35. In this operation of the swing lever31for disengaging locating lug34from the recessed portion17, the swing lever31is pivoted about the pivot shaft26and, therefore the locating lug34is moved along a path of a circular arc whose center is the pivot shaft26.

However, it is difficult for the locating lug34to be released smoothly from the recessed portion17because part of the shape of the locating lug34and the recessed portion17does not correspond to the circular arc of the path.

In the preferred embodiment, since the swing lever31has an elongated hole36through which the pivot shaft26is inserted and, therefore, the swing lever31is movable relative to the pivot shaft26, the locating lug34can be released easily from the recessed portion17. This is because the distance between the pivot shaft26serving as the pivot and the locating lug34serving as the acting point is changed according to the variable clearance between the elongated hole36and the pivot shaft26. In the preferred embodiment of the present invention, the difficulty in releasing the locating lug34from the recessed portion17because of failure in complete correspondence of circular arcs thereof is solves by the provision of the elongated hole36along which the swing lever31is movable relative to the movable base21.

As shown inFIG. 4, when the locating lug34is fully released from the recessed portion17, the locating lug34is positioned in the arcuate portion16of the guide hole15at a position where the locating lug34faces the recessed portion17as indicated by two-dot chain line. In this position, the swing lever31is then turned in clockwise direction as viewed from the top or pushed leftward thereby to pivot the movable base21in clockwise direction. On the other hand, the swing lever31is turned in counter-clockwise direction or pulled rightward to pivot the movable base21counter-clockwise. In pivoting the movable base21in counter-clockwise direction, the locating lug34is positioned facing the recessed portion18which is used for holding the movable base21at a position where the movable base21has turned in counter-clockwise direction for a predetermined distance from the aforementioned center position. InFIG. 4, the locating lug34in this position is shown by two-dot chain line at a position where it faces the recessed portion18. Releasing the swing lever31, the swing lever31is moved by the urging force of the coil spring35in the direction which causes the locating lug34to be engaged with the recessed portion18.

Then, the swing lever31is moved relative to the pivot shaft26as needed thereby to facilitate the engagement of the locating lug34with recessed portion18. In the engagement of the locating lug34with the recessed portion18as shown inFIG. 4, the movable base21is pivoted clockwise relative to the stationary base11as shown inFIG. 5and both lateral sides of the locating lug34are in contact with those of the recessed portion18with no gap formed therebetween. As a result, the vehicle seat assembly20is pivoted about an angle of 17 degrees in clockwise direction relative to an operator's platform facing toward of the vehicle body from the center position. Thus, the front of the body of the operator seated on operator's seat is turned rightward, and the vehicle seat assembly20which has been pivoted clockwise remains at this position unless the swing lever31is operated again.

Referring toFIG. 6, since there is no recessed portion in the arcuate portion16in the range of the guide hole15corresponding to the counter-clockwise pivoting of the movable base21from its center position, the movable base21which have been pivoted counter-clockwise from the center position cannot be maintained in its pivoted position without continuing to hold the swing lever31. In this position, the front of the seated operator's body is turned left. When the operator gets out of the operator's platform, the counter-clockwise pivoting of the vehicle seat assembly20makes the front of the operator's body to face leftward, which makes it easy for the operator to get out of the vehicle.

According to the seat swiveling device of a vehicle of the preferred embodiment, the following effects are achieved.

(1) The swing lever31is movable relative to the pivot shaft26which is inserted through the elongated hole36. Thus, even if the recessed portions17and18and locating lug34are made with large tolerances, the movement of the swing lever31relative to the pivot shaft26makes it easy for the locating lug34to be fitted in the recessed portions17and18with no gap formed therebetween and also for the locating lug34to be disengaged from the recessed portions17and18.

(2) The elongated hole36is formed so as to extend in substantially the same longitudinal direction as the guide hole15along which the engaging locating lug34is move. Thus, the locating lug34is moved along the guide hole15in positioning the engaging locating lug34relative to the recessed portions17and18and, therefore, the engagement of the locating lug34with the recessed portions17and18is facilitated.

(3) The locating lug34and the recessed portions17and18have the substantially same and complementary wedge shape, and the direction of the center axis of the locating lug34is the substantially same as the direction in which the swing lever31is pivoted. Thus, the locating lug34is fitted in the recessed portion17or18with no gap therebetween when the locating lug34is engaged with the recessed portion17or18by swinging the swing lever31.

(4) The swing lever31is subjected to the urging force such that the locating lug34is urged toward the recessed portions17and18or rearwardly by the coil spring35as urging means. Thus, the engagement of the locating lug34with the recessed portions17and18is kept without any operation of the swing lever31.

The present invention is not to be limited to the above embodiment but may be modified within the scope of the invention and it may be practiced in other various ways as exemplified below.

In the preferred embodiment, the swing lever31is operated by manipulation of the grip33of the swing lever31which is located on lateral side of the vehicle seat assembly20. However, means for operating the swing lever31may be installed in an armrest which is provided on the vehicle seat. In this case, the operating means for the swing lever31such as the operating lever installed in the armrest is connected to the swing lever through a wire or the like. The swing lever is pivoted by operation of the operating means.

According to the preferred embodiment, after the locating lug34have been moved from the recessed portions17and18to the arcuate portion16by operation of the swing lever31, the movable base21is pivoted by the operation of the grip33of the swing lever31. However, the vehicle seat assembly20may be pivoted by twisting of the operator's body.

According to the above embodiment, the two recessed portions17and18are provided for holding the movable base21at the center or straightforward position and the position where the movable base21is pivoted clockwise for a predetermined angle from the center position. However, as long as at least the recessed portion17for the center position is provided, the number of the other recessed portions is not limited by the present invention.

According to the preferred embodiment, the spring force of the coil spring35is used as urging force. However, the urging force is not limited to the force of the coil spring35. Any suitable means may be used for applying urging force the swing lever.

Therefore, the present examples and embodiment are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein but may be modified within the scope of the appended claims.