Foldaway baby carriage and folding mechanism employed therein

In order to allow bending of members defining the cross-directional size of a frame of a foldaway baby carriage in association with movement of members forming side surfaces of the frame, side bars rotate with respect to front legs to draw up front leg sleeves through front leg rigid links. At this time, guide pins provided in the front legs are moved in spirally extending guide grooves which are formed in the front leg sleeves, so that the front leg sleeves rotate due to the spiral extension of the guide grooves. Thus, a front leg coupling link extending across the pair of front leg sleeves is bent about bend points. A similar structure is employed in relation to a rear leg coupling member extending across a pair of rear legs and a side bar coupling member extending across a pair of side bars.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a foldaway baby carriage and a folding 
mechanism employed therein, and more particularly, it relates to a 
foldaway baby carriage having a frame whose cross-directional size is 
defined by members which are bendable in association with an operation for 
folding members forming side surfaces of the frame, and a folding 
mechanism employed therein. 
2. Description of the Background Art 
U.S. Pat. No. 4,317,581 (issued on Mar. 2, 1982), granted to Kenzou Kassai, 
describes the basic structure of a foldaway baby carriage, which is of 
interest to the present invention. When the baby carriage disclosed in 
this patent is folded, its horizontal, vertical and cross-directional 
sizes are reduced as compared with an opened state, so that the baby 
carriage is easy to carry and store in the folded state. 
However, the aforementioned foldaway baby carriage still has improvable 
points. 
In particular, it is difficult to reduce the weight of this baby carriage, 
conceivably because of a relatively large number of components. 
The baby carriage includes a large number of components, particularly 
because movement of members forming side surfaces of its frame must be 
interlocked with that of members defining the cross-directional size of 
the frame through a relatively complicated mechanism. Since planes of 
movement of the members forming the side surfaces of the frame are not 
identical nor parallel but perpendicular to those of movement of the 
members defining the cross-directional size of the frame, the mechanism 
for interlocking these members in operation must be capable of performing 
the so-called three-dimensional operation. 
SUMMARY OF THE INVENTION 
Accordingly, an object of the present invention is to provide a folding 
mechanism having a relatively simple structure which can interlock 
movement of members forming side surfaces of the frame of a baby carriage 
with that of members defining the cross-directional size of the frame, and 
a foldaway baby carriage employing such a folding mechanism. 
The present invention provides a folding mechanism which is employed in a 
foldaway baby carriage comprising a horizontal pair of rod members and 
bendable coupling members extending across the pair of rod members, so 
that the coupling members are bent to approach the pair of rod members in 
a folding operation. 
In order to solve the aforementioned technical problem, the inventive 
folding mechanism is characterized in the following structure: 
Each of the coupling members comprises a pair of sleeves which are slidably 
mounted on the rod members to be rotatable about the central axes thereof, 
and a bendable coupling link coupling the pair of sleeves with each other. 
The sleeves are provided with spirally extending guide grooves, while the 
rod members are provided with guide pins which are received in the guide 
grooves. Each coupling member further comprises means for moving the 
sleeves longitudinally along the rod members. 
The present invention also provides a foldaway baby carriage through the 
aforementioned folding mechanism. 
The inventive foldaway baby carriage comprises members forming side 
surfaces of its frame and members extending across such members for 
defining the cross-directional size of the frame. 
The members forming the side surfaces comprise: 
a pair of horizontally extending handrail members, 
a pair of front legs having upper ends which are rotatably coupled to 
relatively front portions of the handrail members and lower ends which are 
connected with front wheels, 
a pair of rear legs having upper ends which are rotatably coupled to 
relatively front portions of the handrail members and lower ends which are 
connected with rear wheels, 
a pair of reversal members having first ends which are rotatably coupled to 
longitudinal centers of the pair of rear legs at first pivotal points, 
a pair of push rods, having lower ends which are rotatably coupled to 
second ends of the pair of reversal members whose positions being upwardly 
separated from the lower ends by prescribed distances are rotatably 
coupled to rear ends of the pair of handrail members, and 
a pair of side bars having front ends which are rotatably coupled to 
longitudinal centers of the pair of front legs at second pivotal points 
and rear ends which are rotatably coupled to the second ends of the pair 
of reversal members. 
On the other hand, the members defining the cross-directional size of the 
frame comprise: 
a front leg coupling member which extends across the pair of front legs in 
positions lower than the second pivotal points, and 
a rear leg coupling member which extends across the pair of rear legs in 
positions lower than the first pivotal points. 
In such a foldaway baby carriage, the aforementioned folding mechanism is 
applied as follows: 
The front leg coupling member comprises a pair of front leg sleeves which 
are slidably mounted on the front leg to be rotatable about the central 
axes thereof, and a bendable front leg coupling link coupling the pair of 
front leg sleeves with each other. The front leg sleeves are provided with 
spirally extending guide grooves, while the front legs are provided with 
guide pins which are received in the guide grooves. 
The side bars are provided with side bar extension parts frontwardly 
extending beyond the second pivotal points, and the side bar extension 
parts are coupled with the front leg sleeves by front leg rigid links. 
On the other hand, the rear leg coupling member comprises a pair of rear 
leg sleeves which are slidably mounted on the rear legs to be rotatable 
about the central axes thereof, and a bendable rear leg coupling link 
coupling the pair of rear leg sleeves with each other. The rear leg 
sleeves are provided with spirally extending guide grooves, while the rear 
legs are provided with guide pins which are received in the guide grooves 
respectively. 
The reversal members are provided with reversal member extension parts 
extending toward the first ends beyond the first pivotal points, and these 
reversal member extension parts are coupled with the rear leg sleeves by 
rear leg rigid links. 
When the sleeves are longitudinally moved along the rod members, the guide 
pins are moved in the spirally extending guide grooves, whereby the 
sleeves are provided with rotary motion. The coupling link is bent in 
response to such rotary motion of the sleeves. Thus, the pair of rod 
members are approached to each other. 
The sleeves thus provide action for converting linear motion to rotary 
motion, which is employed for bending each of the front leg coupling link 
and the rear leg coupling link in the foldaway baby carriage according to 
the present invention. The side bars and the reversal members are driven 
to linearly move the sleeves through the front leg rigid links and the 
rear leg rigid links respectively. 
Thus, the sleeves are linearly moved to rotate at the same time, whereby 
the inventive folding mechanism can be advantageously applied to portions, 
requiring the so-called three-dimensional movement, of a foldaway baby 
carriage. 
When the aforementioned folding mechanism is employed for interlocking 
members forming side surfaces of the frame of a foldaway baby carriage 
with members defining the cross-directional size of the frame in movement, 
it is possible to fold the baby carriage by interlocking the former with 
the latter through a relatively simple mechanism. Thus, it is possible to 
reduce the number of components included in the foldaway baby carriage, 
thereby reducing the weight. 
The foregoing and other objects, features, aspects and advantages of the 
present invention will become more apparent from the following detailed 
description of the present invention when taken in conjunction with the 
accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIGS. 1 to 6 are adapted to illustrate a foldaway baby carriage according 
to an embodiment of the present invention, which includes a folding 
mechanism characterizing the present invention. These figures show only 
the frame of the baby carriage, and a seat for a baby is omitted for 
facilitating easy understanding of the structure of such a frame. In 
general, the seat is provided with a seat portion and a backrest portion. 
FIG. 1 is a right side elevational view showing the baby carriage which is 
in an opened state, and FIG. 2 is a rear elevational view showing the baby 
carriage in the opened state. FIG. 3 is a right side elevational view 
showing the baby carriage which is in a closed state, and FIG. 4 is a 
perspective view showing a principal part of the baby carriage which is in 
an intermediate stage of a folding operation. 
This foldaway baby carriage is generally provided with members forming side 
surfaces of its frame and members extending across the members forming the 
side surfaces for defining the cross-directional size of the frame. 
Further, this baby carriage has a laterally symmetrical structure. 
Therefore, elements which are included in and arranged on both sides of 
the inventive baby carriage are denoted by similar reference numerals. 
The members forming the side surfaces of the frame include the following 
elements: 
A pair of handrail members 1 are arranged to extend in the longitudinal 
direction. Forward ends of the pair of handrail members 1 are coupled with 
each other by a bendable body guard 2. This body guard 2 is preferably 
detachable from the handrail members 1. 
Upper ends of a pair of front legs 3 are rotatably coupled to relatively 
front portions of the handrail members 1 by pivot pins 4. Front wheels 5 
are mounted on lower ends of the front legs 3. 
Further, upper ends of a pair of rear legs 6 are also rotatably coupled to 
the relatively front portions of the handrail members 1 by the pivot pins 
4. While the front and rear legs 3 and 6 are rotatably coupled to the 
handrail members 1 by the common pivot pins 4 in this embodiment, such 
front and rear legs may alternatively be coupled to the handrail members 1 
in a rotatable manner by pivot pins which are different from each other, 
in response to the design of the baby carriage. Rear wheels 7 are mounted 
on lower ends of the rear legs 6. 
First ends of a pair of reversal members 8 are rotatably coupled to 
longitudinal centers of the pair of rear legs 6 through pivot pins 9. As 
clearly shown in FIG. 4, each of the reversal members 8 includes two 
plates, for holding each of the rear legs 6 therebetween. 
Lower ends of a pair of push rods 10 are rotatably coupled to second ends 
of the pair of reversal members 8 by pivot pins 11. Each of these push 
rods 10 is also held between the two plates of each reversal member 8. 
Rear ends of the handrail members 1 are rotatably coupled by pivot pins 12 
to positions of the push rods 10 which are upwardly separated from the 
lower ends by prescribed distances. 
According to this embodiment, upper ends of the pair of push rods 10 are 
coupled with each other by a bendable push rod coupling member 13, which 
defines a handle grip for this baby carriage. An unlocking button 14 
downwardly projects from the central portion of the push rod coupling 
member 13. The unlocking button 14 is pressed to release the baby 
carriage, which is locked in an opened or closed state. When the unlocking 
button 14 is pressed, the push rod coupling member 13 is rendered bendable 
and locking blocks 15, which are interlocked with the unlocking button 14 
through wires (not shown), are upwardly moved along the push rods 10. Upon 
such upward movement, the locking blocks 15, which are regularly urged by 
springs (not shown) downwardly along the push rods 10, engage with the 
upper ends of the reversal members 8 to fix the push rods 10 and the 
reversal members 10 to each other and lock the baby carriage in an opened 
state. In a closed state of the baby carriage, on the other hand, the 
locking blocks 15 engage with longitudinal centers of the reversal members 
8 as shown in FIG. 3, to fix the push rods 10 and the reversal members 8 
to each other and lock the baby carriage in the closed state. 
Front ends of a pair of side bars 16 are rotatably coupled to longitudinal 
centers of the pair of front legs 3. As clearly shown in FIG. 4, end 
pieces 17 are fixed to the front ends of the side bars 16, and pivot pins 
18 pass through both the end pieces 17 and the front legs 3. Rear ends of 
the side bars 16 are rotatably coupled to end portions of the reversal 
members 8. According to this embodiment, the aforementioned pivot pins 11 
for coupling the push rods 10 and the reversal members 8 are also employed 
for such coupling, while end pieces 19 are mounted on the rear ends of the 
side bars 16 in order to absorb difference between the vertical positions 
of the rear ends of the side bars 16 and the pivot pins 11. The pair of 
side bars 16 are adapted to hold the seat portion of the baby carriage. 
On the other hand, the members defining the cross-directional size of the 
frame of this baby carriage includes the following elements: 
A front leg coupling member 20 extends across the pair of front legs 3 in 
positions lower than the pivot pins 18. 
A rear leg coupling member 21 extends across the pair of rear legs 6 in 
positions lower than the pivot pins 9. 
According to this embodiment, further, a side bar coupling member 22 
extends across relatively front portions of the pair of side bars 16. 
The aforementioned push rod coupling member 13 can also be regarded as a 
member defining the cross-directional size of the frame. 
As clearly shown in FIG. 4 in particular, the front leg coupling member 20 
comprises a pair of front leg sleeves 23 which are slidably mounted on the 
front legs 3 to be rotatable about central axes thereof, and a bendable 
front leg coupling link 24 coupling the pair of front leg sleeves 23 with 
each other. According to this embodiment, the front leg coupling link 24 
has two bend points 25, while both ends thereof are fixed to the front leg 
sleeves 23 respectively. 
In this embodiment, the front leg sleeves 23 may be directly arranged on 
the front legs 3, which are formed by pipes having circular sections, so 
that the former are rotatable about central axes of the latter. A similar 
advantage can be attained as to the rear legs 6 and the side bars 16, 
which are formed by pipes having circular sections, as hereinafter 
described. The front legs 3 may not be entirely circular in section, but 
only portions provided with the front leg sleeves 23 may have circular 
sections. Alternatively, the front legs 3 may be provided thereon with 
separate members, whose outer peripheral surfaces are circular in section. 
This also applies to the rear legs 6 and the side bars 16, which are 
described later. 
The front leg sleeves 23 are provided with spirally extending guide grooves 
26. The front legs 3 are provided with guide pins 27, which are received 
in the guide grooves 26. 
FIG. 5 is a developed elevational view showing one of the front leg sleeves 
23. As clearly shown in FIG. 5, a rotation inhibiting part 28, which 
extends in parallel with the axis of each front leg sleeve 23, is provided 
on one end of the guide groove 26. 
The side bars 16 are provided with side bar extension parts 29 frontwardly 
extending beyond the pivot pins 18. According to this embodiment, the side 
bar extension parts 29 are integrated with the end pieces 17. 
The side bar extension parts 29 are coupled with the front leg sleeves 23 
by front leg rigid links 30 respectively. The front leg rigid links 30 are 
coupled with the front leg sleeves 23 preferably in a kind of universal 
joint manner, in order to allow rotation of the front leg sleeves 23. 
A structure which is substantially identical to the aforementioned 
structure related to the front leg coupling member 20 is employed in the 
rear leg coupling member 21. 
The rear leg coupling member 21 is provided with a pair of rear leg sleeves 
31 which are slidably mounted on the rear legs 6 to be rotatable about 
central axes thereof, and a bendable rear leg coupling link 32 coupling 
the pair of rear leg sleeves 31 with each other. The rear leg coupling 
link 32 has two bend points 33, and both ends thereof are fixed to the 
rear leg sleeves 31 respectively. 
The rear leg sleeves 31 are provided with spirally extending guide grooves 
34. The rear legs 6 are provided with guide pins 35, which are received in 
the guide grooves 34. 
The guide grooves 34 are provided in first ends with rotation inhibiting 
parts 36, similarly to the aforementioned guide grooves 26. 
The reversal members 8 are provided with reversal member extension parts 37 
endwardly extending beyond the pivot pins 9. 
The reversal member extension parts 37 and the rear leg sleeves 31 are 
coupled with each other by rear leg rigid links 38 respectively. The rear 
leg rigid links 38 are coupled with the rear leg sleeves 31 preferably in 
a kind of universal joint manner, in order to allow rotation of the rear 
leg sleeves 31. 
The side bar coupling member 22 comprises a pair of side bar sleeves 39 
which are slidably mounted on the side bars 16 to be rotatable about 
central axes thereof, and a bendable side bar coupling link 40 coupling 
the pair of side bar sleeves 39 with each other. According to this 
embodiment, the side bar coupling link 40 has two bend points 41, and both 
ends thereof are fixed to the side bar sleeves 39 respectively. 
The side bar sleeves 39 are provided with spirally extending guide grooves 
42. The side bars 16 are provided with guide pins 43, which are received 
in the guide grooves 42 respectively. 
FIG. 6 is a developed elevational view showing one of the side bar sleeves 
39. 
Each side bar sleeve 39 is provided with a sidewardly extending driving 
member 44. This driving member 44 comes into contact with each front leg 3 
in an initial stage of an operation for closing the baby carriage which is 
in an opened state, so that each front leg 3 provides force for sliding 
each side bar sleeve 39 on each side bar 16. 
The operation of the foldaway baby carriage, which has been described 
mainly with reference to the structure, is now described. 
In an opened state of the baby carriage as shown in FIGS. 1 and 2, the 
reversal members 8 have rotated along the upper half portions of the rear 
legs 6, thereby bringing the push rods 10 into relatively upper positions 
in the members forming the side surfaces of the frame. In this state, the 
locking blocks 15 inhibit the push rods 10 and the reversal members 8 from 
relative movement, whereby the push rods 10, the reversal members 8, the 
handrail members 1 and the rear legs 6 define fixed triangles. The front 
legs 3, the rear legs 6 and the side bars 16 also define other triangles. 
Thus, the baby carriage is maintained in the opened state. On the other 
hand, the members defining the cross-directional size of the baby carriage 
are inhibited from movement in response to such fixation of the members 
forming the side surfaces. In particular, it is noted that the front leg 
sleeves 23 and the rear leg sleeves 31 are currently not rotatable about 
the central axes of the front legs 3 and the rear legs 6 respectively 
since the guide pins 27 and 35 are located in the rotation inhibiting 
parts 28 and 36 of the guide grooves 26 and 34 respectively. Thus, the 
front leg coupling link 24 and the rear leg coupling link 32 are strongly 
inhibited from bending. 
In order to fold the foldaway baby carriage to bring the same from such an 
opened state into a closed state, the unlocking button 14 is first pressed 
to upwardly displace the locking blocks 15 along the push rods 10. Thus, 
the locking blocks 15 disengage from the reversal members 8. 
Then, hands holding the push rod coupling members 13 are pulled back while 
pressing the unlocking button 14, to rearwardly incline the baby carriage 
and raise up the front wheels 5 while keeping the rear wheels 7 in contact 
with the ground. Thus, the push rod coupling member 13 is bent and the 
reversal members 8 rotate along arrow 45. In the state shown in FIG. 4, 
the reversal members 8 have rotated to some extent in the direction of the 
arrow 45. 
Following such rotation of the reversal members 8, the rear leg rigid links 
38, which are coupled with the reversal member extension parts 37, draw up 
the rear leg sleeves 31 along the rear legs 6 as shown by arrow 46. The 
guide pins 35 are moved in the guide grooves 34 in response to this, so 
that the rear leg sleeves 31 rotate along arrow 47 due to the spiral 
extension of the guide grooves 34. Thus, the rear leg coupling link 32 is 
bent about the bend points 33. 
The aforementioned rotation of the reversal members 8 is also transmitted 
to the front legs 3 through the side bars 16, to draw the front legs 3 
toward the rear legs 6. 
At this time, the side bars 16 rotate along arrow 48 with respect to the 
front legs 3. Thus, the front leg rigid links 30, which are coupled with 
the side bar extension parts 29, draw up the front leg sleeves 23 along 
the front legs 3, as shown by arrow 49. The guide pins 27 are moved in the 
guide grooves 26 at this time, so that the front leg sleeves 23 rotate 
along arrow 50 due to the spiral extension of the guide grooves 26. Thus, 
the front leg coupling link 24 is bent about the bend points 25. 
As the result of such rotation of the side bars 16, the front legs 3 
provide the side bar sleeves 39 with force for sliding the same along the 
side bars 16 as shown by arrow 51. The guide pins 43 are moved in the 
guide grooves 42 at this time, so that the side bar sleeves 39 rotate 
along arrow 52 due to the spiral extension of the guide grooves 42. Thus, 
the side bar coupling link 40 is bent about the bend points 41. 
The aforementioned operation further progresses to finally attain the 
closed state shown in FIG. 3. In this state, the locking blocks 15 again 
engage with other portions of the reversal members 8, thereby maintaining 
the baby carriage in the closed state. Since the front and rear wheels 5 
and 7 are horizontally aligned with each other, the baby carriage is 
self-sustainable in such a closed state. As understood from the states of 
the push rod coupling member 13, the front leg coupling link 24, the rear 
leg coupling link 32 and the side bar coupling link 40 shown in FIG. 3, 
the baby carriage is so folded that the front wheels 5 and the rear wheels 
7 are substantially in contact with each other as to the cross direction. 
In order to open the baby carriage as shown in FIGS. 1 and 2 from the 
closed state shown in FIG. 3, the aforementioned steps are basically 
carried out in reverse order through the intermediate state shown in FIG. 
4, similarly to the above. 
While the present invention has been described with reference to the 
preferred embodiment, various modifications are available within the scope 
of the present invention. Therefore, the aforementioned embodiment 
includes elements other than those requisite for the present invention. 
For example, the side bar sleeves 39 and the side bar coupling link 40 
provided in relation to the side bar coupling member 22 may be omitted if 
a member corresponding to the side bar coupling member 22 is naturally 
bent upon mutual approximation of the pair of side bars 16. 
Further, the side bar coupling member 22, which is adapted to reinforce the 
baby carriage in its opened state, may be omitted if such reinforcement is 
not necessary. 
This also applies to the push rod coupling member 13. Namely, the push rod 
coupling member 13, which is adapted to reinforce the baby carriage in its 
opened state, may be omitted if such reinforcement is not necessary. If 
the baby carriage is reduced in strength in its opened state due to such 
omission of the push rod coupling member 13, another member may be 
employed for cross-directionally coupling other portions of the baby 
carriage with each other. For example, a member which cross-directionally 
extends in the backrest portion of the seat of the baby carriage may be 
employed for reinforcing the same in its opened state. 
The aforementioned folding mechanism, which includes the coupling members 
20, 21 and 22 having the sleeves 23, 31 and 39 and the coupling links 24, 
32 and 40 with the guide grooves 26, 34 and 42 formed in the sleeves 23, 
31 and 39 and the guide pins 27, 35 and 43 provided in rod or bar members 
such as the front legs 3, the rear legs 6 and the side bars 16, is also 
applicable to other portions of the foldaway baby carriage, or a foldaway 
baby carriage different from that shown in the drawings.