Backrest structure for strollers

[0001] The invention relates to a backrest structure for strollers that is movable synchronously with the stroller frame and adjustable angularly in multiple stages.

[0002] Strollers (infant carriers) are generally designed with a collapsible function to facilitate carrying and storage. Many folding features have been developed over the years to enhance operation effectiveness. For instance, U.S. Pat. No. 5,454,584 discloses a collapsible stroller that has a frame movable between a collapsed position and an operating position. It has a back movable between a first position (sitting position) and a second position (recumbent position). A latch means is provided between the frame and the back that includes a boss in a rear leg tube and a slot on a latch. The boss may be positioned within the slot to keep the back at the first position. The latch means, back and frame are so designed that when the back is at the first position, the frame may be moved from the operating position to the collapsed position, and when the boss is separated from the slot, the latch means automatically releases the back to allow the back to move (drop) automatically to the second position. Hence users do not need to release the back separately to fold the stroller. Although the cited patent claims it enables the back to move (drop) automatically when the stroller is folding, the boss cannot always overcome the friction between the slot and the boss and separate smoothly from the slot. As a result, the back does not always move automatically as desired. Thus users have to release the back separately to fold the stroller. There is a need to design an improved backrest mechanism to fold the back effectively and safely.

[0003] The primary object of the invention is to provide a backrest structure that has a linkage bar between the frame and the backrest so that the backrest may be folded or extended synchronously with the collapsing or extension of the frame. The backrest structure maintains the stability of the backrest while the stroller is moving to improve the safety of the infant.

[0004] Another object of the invention is to provide a backrest adjusting means to enable the backrest to interact with the linkage bar and provide multiple stages of adjustment for the angle of the backrest to enhance comfort for the infant.

[0005] According to the invention, the stroller includes a frame movable between a sitting position and a collapsed position and a loading rack having an anchor section, which has a portion for seating the passenger. The backrest structure of the invention includes a backrest adjusting means that is pivotally mounted on the anchor section, a movable backrest that is pivotally engaged with the backrest adjusting means and is movable between a first position and a second position when the frame is at the sitting positionwith the passenger sitting generally upright when the backrest is at the first position and lying rearwards when the backrest is at the second positionand a linkage bar with a first end pivotally engaged with the frame and a second end pivotally engaged with the backrest adjusting means. When the frame is at the sitting position, the linkage bar supports the backrest adjusting means and the backrest at the first position. When the frame is moved from the sitting position to the collapsed position, the frame moves the linkage bar and pushes the backrest adjusting means to make the backrest turn synchronously with the frame and fold at the second position to enable the stroller be folded smoothly. In addition, when the frame is at the sitting position, the backrest adjusting means may be adjusted in multiple stages to alter the angle of the backrest to suit the passenger's requirements.

[0006] The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings.

[0007] FIG. 1 is a schematic view of the stroller of the invention at the sitting position.

[0008] FIG. 2 is an exploded view of the backrest adjusting means of the backrest structure of the invention.

[0009] FIG. 3 is a schematic view of the backrest structure of the invention at the lying position according to FIG. 1.

[0010] FIG. 4 is a schematic view of the stroller of the invention at the collapsed position.

[0011] FIG. 5 is a perspective view of the invention according to FIG. 1, with the backrest at the first position.

[0012] FIG. 6 is a fragmentary perspective and enlarged view of the invention according to FIG. 4, with the backrest at the second position.

[0013] Refer to FIG. 1 for a stroller 1 at a sitting position. The stroller 1 has a frame 10 that includes a push tube (first rack) 11, a front leg tube (second rack) 12, a rear leg tube (third rack) 13, a latch means 14 and a seat tube (loading rack) 20. The seat tube includes an anchor section 20a that has a portion for seating a passenger.

[0014] The push tube 11 has a first end connecting to a handle 11a and a second end pivotally engaging with the latch means 14. The front leg tube 12 has a first end fastening to the latch means 14 and a second end engaging with a plurality of front wheels 12a. The front leg tube 12 further has a pivotal point 12b between the first end and the second end to pivotally engage with the anchor section of the seat tube. The rear leg tube 13 has a first end pivotally engaging with the latch means 14 and a second end engaging with a plurality of rear wheels 13a. The rear leg tube 13 further has a pivotal point 13b between the first end and the second end to pivotally engage with the anchor section of the seat tube. The latch means 14 may latch or separate the push tube 11 and the front leg tube 12. The structure of the latch means 14 is known in the art and forms no part of the invention. Any conventional latch mechanism that provides latching or separating functions may be adopted, such as the one disclosed in U.S. Pat. No. 5,454,584.

[0015] The backrest structure for the stroller of the invention includes a movable backrest 20b, a backrest adjusting means 40 and a linkage bar 30.

[0016] Referring to FIGS. 1 and 2, the backrest adjusting means 40 includes a rotary member 41, an anchor member 42 and a spring 60. The rotary member 41 has one end forming a stepwise surface 41 and has a first pivotal point 41 a to pivotally engage with the backrest 20b, a second pivotal point 41b to pivotally engage with the anchor section 20a, and a third pivotal point 41c.

[0017] The anchor member 42 is coupled with the backrest 20b and has one end forming a stepwise surface 42 mating and engaging with the stepwise surface 41 of the rotary member 41. The spring 60 is located inside the backrest 20b to provide force to allow the anchor member 42 to engage with the rotary member 41. When the stroller 1 is at the sitting position (as shown in FIG. 1), the stepwise surface 42 of the anchor member 42 engages with the stepwise surface 41 of the rotary member 41, and the backrest 20b is erected upwards at the first position (as shown in FIG. 1) to provide back support for the sitting infant or child. When the anchor member 42 is separated from the rotary member 41, the backrest 20b may be turned about the first pivotal point 41a to the lying position (as shown in FIG. 3).

[0018] When the stepwise surfaces 41 and 42 have only one step, the backrest has only the first position and the lying position for two-stage adjustment. When the stepwise surfaces 41 and 42 have more than one step, the backrest may have adjusting inclination of three stages or more.

[0019] The linkage bar 30 has one end 30a pivotally engaging with the pivotal point 13c of the rear leg tube 13 and a second end 30b pivotally engaging with the third pivotal point 41c of the rotary member 41. When the stroller is at the sitting position and the backrest 20b is at the first position and erecting upwards, the linkage bar 30 supports the rotary member 41 and the backrest 20b.

[0020] When the stroller is moved from the sitting position to the collapsed position for folding (as shown in FIG. 4), the rear leg tube 13 turns about the pivotal point 14a of the latch means 14, drives the linkage bar 30 and pushes the backrest adjusting means 40 to turn about the second pivotal point 41b. Thus the backrest 20b is turned synchronously with the rear leg tube 13 to the second position for folding (as shown in FIG. 6).

[0021] The following is a summary of the movement principle and function of the backrest structure of the invention. When the stroller 1 is moved from the sitting position (as shown in FIG. 1) to the collapsed position (shown in FIGS. 4 and 6), first, the user releases the latched condition of the latch means 14 to separate the push tube 11 from the front leg tube 12. Next, the user moves the handle 11a of the push tube 11 to turn clockwise about the pivotal point 14b of the latch means according to FIG. 1, the push tube 11 is moved close to the front leg tube 12 and drives the rear leg tube 13 at the same time, and the rear leg tube 13 turns about the pivotal point 14a of the latch means and moves to the front leg tube 12. Meanwhile, the rear leg tube 13 drives the anchor section 20a of the seat tube to turn about the pivotal point 12b and moves to the front leg tube 12. The rear leg tube 13 drives the linkage bar 30 at the same time. The linkage bar 30 exerts force on the third pivotal point 41c of the backrest adjusting means 40 through one end 30b to make the backrest adjusting means 40 turn clockwise about the second pivotal point 41b. Thereby the backrest 20, which is folded onto the backrest adjusting means 40, is turned synchronously towards the seat tube 20a until it reaches the second position (as shown in FIG. 6).

[0022] In contrast, when the stroller 1 is moved from the collapsed position (FIG. 4) to the sitting position (FIG. 1), the backrest adjusting means 40 is driven by the linkage bar 30 and turns the backrest 20b synchronously to the sitting position of the stroller 1 for anchoring (FIG. 1).

[0023] In addition, when the stroller 1 is at the sitting position, and is moved to separate the complementary surfaces 41 and 42 of the rotary member 41 and the anchor member 42, the backrest 20b may be turned about the first pivotal point 41a to the lying position, which is almost on the same plane as a portion of the anchor section 20a, so that the infant may be laid thereon. It is to be understood that in such a condition, when folding the stroller, the linkage bar 30 also drives the rear leg tube 13 and the backrest adjusting means 40 to move synchronously. During the folding process the anchor member 42 of the backrest adjusting means 40 automatically latches onto the rotary member 41, as shown in FIG. 6.

[0024] The novel design of the backrest structure of the invention enables the backrest of the stroller to turn synchronously with the collapsing or extending of the frame for folding or anchoring. In addition, the linkage bar can support the backrest adjusting means 40, and therefore can maintain the stability of the backrest 20b latched on the backrest adjusting means 40 to enhance the safety of the infant while the stroller is moving.

[0025] While the preferred embodiment of the invention has been set forth for the purpose of disclosure, modifications of the disclosed embodiment of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the invention.