US 3540152 A
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Nov. 17, 1970 BENY ETAL 3,540,152
TOY WITH VARIABLE TORQUE-PRODUCING MEANS- Filed Aug. 22. 1968 2 Sheets-Sheet l 12 a 6418 "4? f I Nov. 17; 1970 J, Y E'I'AL 3,540,152
' TQY WITH VARIABLE TORQUE-PRODUCING MEANS Filed Aug. 22. 1968 2 Sheets-Sheet 2 fiqflf 122 126 118 132 /VVAW7'II) J21; 'Il/VI' 1 a/wup a Akin/4Y4 United States Patent 3,540,152 TOY WITH VARIABLE TORQUE-PRODUCING MEANS Janos Beny, Manhattan Beach, and Donald Charles Hartling, Garden Grove, Califi, assignors to Mattel, Inc.,
Hawthorne, Calif., a corporation of Delaware Filed Aug. 22, 1968, Ser. No. 754,633 Int. Cl. A63h 17/00, 17/29 US. Cl. 46-206 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION Field of the invention This invention relates to motor driven toys.
Description of the prior art Motion-producing toys such as toy vehicles are generally provided with small motors, and with gear transmissions which can provide any driving speed within a wide range. Higher speeds often make the vehicle or other toy more entertaining, but the resulting lower torque increases the likelihood of stalling, and a compromise is resorted to.
The compromise required between speed and torque results in an important limitation in the case of certain toys such as bulldozers and other track vehicles, which are desgined to clamb steep grades or over steep obstacles. Such vehicles are generally provided with high driving torques by resorting to very low speeds, and therefore they move at low speeds even on level ground when little driving torque is required. The compromise is especially severe in the case of toys driven by small electric motors whose output torque does not increase greatly as speed increases. The compromise is also important in the case of spring motors, although some of these motors utilize rapidly rotating propellors or vanes to regulate speed, so that a decrease in speed results in substantial increase in driving torque.
OBJECTS AND SUMMARY OF THE INVENTION One object of the invention is to provide a toy which automatically shifts speed in accordance with the load imposed on it.
Another object is to provide an electric motor driven toy which normally operates at high speed but which is resistant to stalling.
Still another object is to provide a toy vehicle of a type designed to move over difficult terrain, which operates at high speed over easily-traversed terrain.
In accordance with the present invention, a toy is provided which has a power transmission that shifts in response to the load or output torque, to prevent stalling and yet maintain high speeds under light loading conditions. The transmission includes coupling elements which are spring biased together but which are pushed apart by the torque. At high loads, one coupling element is shifted, and it then engages a low-speed gear to drive the toy at a low speed. When the load is reduced, the spring biasing returns the shifted element to its former position where it engages a high speed gear to drive the toy at a high speed.
3,540,152 Patented Nov. 17, 1970 In accordance with one embodiment of the invention, a toy track vehicle is provided which is driven by an electric motor. The motor is coupled through a reducing transmission to a track driving wheel on an output shaft. The transmission includes a small gear with ratchets on its side, the small gear being mounted on the output shaft so it can shift axially thereon. At light loads, the small gear is engaged at its periphery with a rapidly rotating gear to drive the vehicle at a high speed. At high loads, the small gear is shifted axially, whereby it disengages from the rapidly rotating gear, and is driven by a slowly rotating member which engages the ratchets on its side.
The axial shifting of the small gear is accomplished by a pair of coupling elements, one fixed to the small gear and the other to the wheel which drives the track. The coupling elements have inclined surfaces that tend to push them apart, to thereby push the small gear to a position where it is driven at low speed. A spring resists such shifting, but a high torque results in a force that overcomes the spring bias.
While the transmission of the invention is useful in toy vehicles, it is also useful in other motion-producing toys which are subject to varying loads, such as toy cranes.
The novel features of the invention are set forth with particularity in the appended claims. The invention will be best understood from the following description when read in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a toy crawler vehicle constructed in accordance with the invention.
FIG. 2 is a sectional bottom view of the vehicle of FIG. 1.
FIG. 3 is a partial perspective view, showing a pair of transmission elements.
FIG. 4 is a partial bottom view of the vehicle of FIG. 1; and
FIG. 5 is a partial bottom View of another embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates a crawler-type toy vehicle comprising a frame 10 propelled by a single track 12 that extends around the frame. An electric motor energized by a pair of batteries 16, is coupled by a transmission to a pair of drive wheels 20 and 22 at the rear of the vehicle. The drive wheels 20, 22 are engaged with the inside of the track 12 to drive it and thereby propel the vehicle. Three sets of idler wheels 24, 26 and 28 hold the track taut in its extension about the frame. An on-off switch 30 on a battery-access cover 32 controls energization of the motor.
The vehicle is designed to move at high speed on level surfaces or downgrades, and yet to crawl over steep obstacles without stalling. This ability is achieved by a novel transmission, which automatically shifts between a highspeed-low-torque output and a low-speed-high-torque output in accordance with the load, that is, the resistance to rotation of the track-driving wheels 20 and 22. Thus, a small motor can be used for normally high speed propulsion without the likelihood of stalling at high loads.
As shown in FIG. 2, the transmission 18 includes a first or motor shaft 34 on the motor 14, a second shaft 36, a third shaft 38, a fourth shaft 40, and a fifth shaft 42. Simple speed reduction is obtained between the motor shaft 34 and the fourth shaft 40 by power transmission through a motor pinion 43, gear 44, pinion 46, gear 48, pinion 50, and gear 52, respectively. However, power transmission between gears on the fourth shaft 40 and elements on the fifth shaft 42 can be accomplished in either of two ways. Under light loading, a fast gear 54 drives an output gear 56 on the fifth shaft to cause rapid vehicle propulsion. Under heavy loading, the output gear shifts axially-in the direction of arrow '68 to disengage from the fast gear 54. Then, the'output gear 56 is driven by a slow gear 58 through an over-riding clutch 72. The slow gear 58 receives power from a slow pinion 60 on the fourth shaft, to provide slow speed but high torque vehicle propulsion.
Shifting between high and low speed propulsion is accomplished by axial shifting of the output gear 56. The output gear is mounted on a hub or coupling member 62 which is free to slide axially on the fifth shaft 42. As shown more clearly in FIG. 4, one end of the hub forms an inclined surface 621. Another coupling member 64, which is fixed to the drive wheel 20, also has an inclined surface 64I. The incline of the surfaces 62I and 64I are with respect to an imaginary plane which passes through the axis of the fifth shaft, and it results in an axiallydirected force. That is, when the coupling member 62 turns in the direction of arrow 66, the surface 641 pushes the member 62 axially in the direction of arrow 68.
A spring 70 extends between the drive Wheel 22 and the slow gear 58, to press the slow gear 58 and output gear 56 in a direction opposite to the arrow '68. When the torque or load increases sufiiciently, the axial component of force applied by surface 62I on surface 641 (force in the direction of arrow) is greater than the spring bias, and the element 62 and gear 56 thereon shift axially to the position shown in FIG. 4. In this position, the output gear disengages from the fast gear 54 on the fourth shaft. The output gear 56 can then be driven by the slow gear 58 through the over-riding clutch 72. The hub 78 of the drive wheel 22 serves as a stopping memher that prevents too great an axial shift of the output and slow gears 56 and 58 which would result in complete disengagement of the coupling members 62 and 64. Thus, either of two transmission elements, the fast gear 54 and the slow gear 58, can be engaged with the output gear to couple it at either of two speeds to the motor. The inclined surfaces respond to the transmitted torque to determine which of the transmission elements is engaged.
The slow gear 58 is mounted for free wheeling on the fifth shaft 42. This gear 58 shifts axially along with the output gear 56. However, it is always engaged with the slow pinion 60, so it is constantly turning when the motor is on, though always at a low speed. The overriding clutch 72 is constructed so that the slow gear 58 can drive the output gear 56 in the direction of arrow 66, but cannot hold back the output gear from turning faster in that direction. When the output gear 56 is engaged with the fast gear 54, as shown in FIG. 2, the output gear is rotated at four times the speed of the slow gear 58. As a result, the over-riding clutch then slips and the slow gear is not used. However, when the output gear 56 is axially shifted to the position shown in FIG. 4, it can be driven only by the slow gear, and the clutch 72 is engaged.
Due to the one-fourth lower speed of the slow gear 58, it can apply four times as much torque as can be applied by the high speed gear before the motor stalls. The function of the over-riding clutch may be thought of as to permit output gear rotation at any speed in excess of the slow gear speed, but to assure that the output gear does not rotate any slower. FIG. 3 shows the over-riding clutch elements 74 and 76 on the slow and output gears, respectively. The clutch elements form axially directed projections with a gradually rising end 77 and an abrupt end 79 which act like ratchets that slip past one another if the output gear 56 is rotating faster than the slow gear 58. The spring 70 presses the clutch elements together to assure their engagement.
The use of an over-riding clutch is important in assuring that complete shifting will occur. The function of the clutch can be understood by considering a design without it. For example, the gears 56 and 58 could be fixed together instead of coupling them through an over-riding clutch, and in addition the pinion 60 would be made narrow so that it engaged the slow gear 58 only after an axial shift caused by high torque. However, such an axial shift might not occur, because as soon as the output gear 56 shifted enough to disengage from the gear 54, but not enough for gears 58 and 60 to engage, output torque would drop to zero. Then the spring 70 would push the output gear back toward its original position, and the output gear would keep on shifting slightly back and forth while the vehicle remained stalled.
The torque at which the output gear is axially shifted is controlled by the spring force and the angle of the inclined surfaces 621 and 64I. For example, an inclined angle A of 45 for incline surfaces at an average radius of one-eighth inch from the center of the fifth shaft 42, and a preload of the spring 70 of one pound results in a shift at a torque of 8 inch-pounds. Static friction between the inclined surfaces 621 and 641 tends to prevent shifting unless a somewhat higher torque is encountered. To overcome static friction, a relatively steep incline angle, preferably more than about 20, is used, and at least one of the incline surfaces is of a low friction material (e.g. a static coeificient of friction below 0.1 on steel or on itself), such as Teflon. While both coupling members have inclined surfaces, shifting will occur even if only one member has an inclined surface.
FIG. 5 illustrates another embodiment of the invention which enables shifting between four speeds. This embodiment of the invention includes a motor shaft and second shaft, neither of which are shown, and a third shaft 100. all of which are similar to those in the previously described embodiment. However, the fourth shaft 102 has four gears 104, 106, 108, and for driving the fifth shaft 112 at any one of four speeds. A drive wheel 20A is fixed to a coupling element 114 which has a long inclined surface 1141. This surface engages the inclined surface 116I of another coupling element 116 which is fixed to an output gear 118.
At low loads, the output gear 118 is engaged with the fast gear 110, to propel the vehicle at a high speed. At a first intermediate load, the torque is sufiicient to produce an axial force, by reason of engagement of the inclined surface 114I on the coupling element 116, to overcome the preload force of a first spring 120. The output gear 118, a first intermediate gear 122 and a bushing then shift axially. The output gear 118 is then disengaged from gear 110, but first intermediate gear 122 is still engaged with gear 108. The intermediate gear 122 can then drive the output gear 118 through a first over-riding clutch 124 which is similar to the clutch described in the foregoing embodiment.
At high intermediate loads, the torque is sufiicient for the coupling element 114 to push the other element 116 with a high intermediate axial force. The output gear 118, first lntermediate gear 122, and bushing 125 then move axially until gear 122 abuts the side of a second intermediate gear 126. The gear 122 is then disengaged from gear 108, and gear 126 drives the output gear through a clutch 128, which can be of the over-riding type, and through gear 118 and clutch 124. The gear 126 is rotated slowly, but can supply a high intermediate torque.
At very high loads, the axial force is sufficient to overcome the combined forces of spring 120 and the preload of a second spring 128. Then only a high load gear 130 is driven, an over-riding clutch 132 is engaged, and the output gear 118 is driven at a very low speed. Further axial movement of the coupling element 116 away from the other element 114 is prevented by reason of the complete collapse of spring 120 wherein the coils of the spring stack or abut each other.
Thus, the invention provides a torque-responsive transmission which substantially selects a gear train driving path which produces the required torque. The transmission is useful in a variety of motion toys which may be subjected to large variations in drag or load, such as train locomotives, track vehicles, and cranes. Although particular embodiments of the invention have been described and illustrated herein, it is recognized that modification and variations may readily occur to those skilled in the art.
What is claimed is:
1. In a motor driven toy;
a rotatable output shaft;
at least two rotary driving members drivingly connected to said motor for rotation thereby at different speeds;
an output member axially slidable on said output shaft for movement into and out of driving engagement with one of said driving members and having an axial end face extending oblique to said shaft;
driven means fixed on said shaft and engageable with said end face;
resilient means urging said output member toward said driven means; and
one-way clutch means drivingly connecting the other of said driving members to said output member.
2. A toy as defined in claim 1 wherein said rotary driving members each comprises a gear, said one being rotatable about an axis laterally adjacent said output shaft and the other being rotatable about said output shaft;
said output member including a gear movable along said output shaft into and out of mesh with the gear comprising said one driving member.
3. A toy comprising:
a pair of rotary coupling elements for transmitting torque, at least one of which has an inclined surface oblique to its axis of rotation and engaged with the other element to develop a separating force dependent upon the transmitted torque;
means for mounting a first of said coupling elements for movement along said axis toward and away from a second of said elements;
means for rotating said first element at a plurality of speeds dependent upon its position relative to said second element;
means for biasing said elements together;
output means coupled to said second element for providing a desired output rotation;
said means for mounting said first coupling element comprising shaft means for guiding said first element in axial translation thereon between first and second positions; and
said means for driving said first element comprising motor means,
first and second gear means drivingly coupled to said motor means,
third gear means attached to said first coupling element for engagement and disengagement with said first gear means when said coupling element is in said first and second positions, respectively,
fourth gear means mounted coaxially with said third gear means and axially movable with it, said fourth gear means being engaged with said second gear means when said coupling element is in both its first and second positions, and
over-riding clutch means for transmitting driving forces only from said fourth to said third gear means for a predetermined direction of rotation of said motor means, said fourth gear means constructed for faster rotation of said third gear means than said second gear means when both are engaged with said first and second gear means, respectively.
4. A toy for automatically shifting speed in accordance with load comprising:
a drive wheel;
a first coupling member mounted on said shaft and engaged with said drive wheel to turn it;
a second coupling member mounted on said shaft for axial movement toward and away from said first coupling member;
said coupling members having a pair of engaging surfaces for rotatably coupling them, atleast one of said surfaces inclined to a plane which passes through the axis of said shaft;
means for biasing said first and second coupling members toward each other;
an output gear mounted on said second coupling member for rotational and axial movement therewith;
a low-speed gear rotatably mounted on said shaft;
over-riding clutch means coupling said low-speed gear to drive said output gear;
means for driving said output gear at a predetermined high speed when said second coupling member is nearest to said first coupling member and being disconnected therefrom when said output gear is moved away from said first coupling member; and
means for driving said low-speed gear at a predetermined low speed at least when said second coupling member is moved away from said first coupling member.
5. The toy described in claim 4 wherein:
said low-speed gear is positioned on a side of said output gear opposite said first coupling member;
said over-riding clutch means comprise an axially directed projection with a gradually rising end and an abrupt end mounted on one of said gears and another projection on the other gear; and
said means for biasing comprises a spring which is preloaded to press said low-speed gear axially toward said output gear.
6. The toy described in claim 4 including:
stop means for limiting the axial movement of said second coupling element away from said first coupling element to prevent their rotational disengagement.
7. The toy described in claim 4 wherein:
said means for driving said output gear comprises a motor and a first connecting gear of predetermined diameter coupled to said motor, said first gear positioned to engage said output gear except upon an axial shift of said output gear exceeding a predetermined amount; and
said means for driving said low-speed gear comprises a second connecting gear coupled to said first connecting gear and positioned to engage said low-speed gear, said second connecting gear being of smaller diameter than said first connecting gear and of a width sufiicient for continuous engagement with said low-speed gear during an axial shift of said lowspeed gear equal to said predetermined amount.
8. The toy described in claim 4 including:
a third gear mounted on said shaft;
second over-riding clutch means for engaging said third gear with said low-speed gear to drive it; and
means for driving said third gear at a speed which is less than said predetermined low speed of said lowspeed gear; and wherein said second coupling element is movable to at least three axial positions; and
said means for driving said low-speed gear is positioned to disengage from said low-speed gear when said second coupling element is in a third axial position furthest from said first coupling element.
9. A toy vehicle comprising:
a vehicle frame;
a motor mounted on said frame;
drive wheel means mounted on said frame for driving said vehicle;
a reduction gear train coupled to said motor;
a first shaft;
a first gear of predetermined diameter mounted on said first shaft and coupled to said reduction gear train;
a second gear of smaller diameter than said first gear, said second gear rotatably fixed to said first gear;
a second shaft;
an output gear mounted on said second shaft and axially shiftable thereon between first and second positions, said output gear engaged with said first gear only when said output gear is in said first axial position;
a low-speed gear mounted on said drive shaft and axially shiftable with said output gear, said low-speed gear engaged with said second gear in both of said axial positions;
over-riding clutch means for coupling said low-speed gear to drive said output gear; and
a pair of coupling elements, including a first element fixed to said Output gear and a second element coupled to said drive wheel means for transmitting driving torque to it, said coupling elements including means for separating them in accordance with the torque transmitted between them, to axially shift said first coupling element and the output gear fixed thereto. 1 0. The toy vehicle described in claim 9 wherein: said means for separating said coupling elements includes an inclined surface on at least one of said elements; and including a spring for biasing said coupling elements toward each other,
References Cited UNITED STATES PATENTS 1,780,858 11/1930 Bearns 74337 X 1,810,450 6/1931 Von Broembsen 74337 1,979,080 10/1934 Roeder 74337 2,098,716 11/1937 Budlong 74337 X 2,102,624 12/1937 Hopson 74-337 2,540,858 2/1951 Behn 74-337 X 3,377,742 4/1968 Sheldon et a1 46243 1,754,307 4/ 1930 Conboy 46-2l9 F. BARRY SHAY, Primary Examiner US. Cl. X.R.