Source: http://www.google.com/patents/US4756202?dq=6966484
Timestamp: 2015-03-29 21:28:20
Document Index: 62761818

Matched Legal Cases: ['art 20', 'art 20', 'art 20', 'art 20', 'art 20', 'art 20', 'art 20', 'art 124', 'art 120', 'art 125', 'art 124', 'art 124', 'art 125', 'art 124', 'art 124', 'arts 124', 'art 124', 'art 125', 'art 125']

Patent US4756202 - Transmission gearing - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsA transmission gearing in which an eccentric cam includes first and second eccentric cam parts and a cam follower has contact faces abutting these eccentric cam parts so that, when a driving source rotates either in normal or reverse direction, the gearing provides as an output one of two different directional...http://www.google.com/patents/US4756202?utm_source=gb-gplus-sharePatent US4756202 - Transmission gearingAdvanced Patent SearchPublication numberUS4756202 APublication typeGrantApplication numberUS 07/013,043Publication dateJul 12, 1988Filing dateFeb 10, 1987Priority dateFeb 21, 1986Fee statusPaidAlso published asDE3705461A1, DE3705461C2Publication number013043, 07013043, US 4756202 A, US 4756202A, US-A-4756202, US4756202 A, US4756202AInventorsYoji KawamotoOriginal AssigneeMatsushita Electric Works, Ltd.Export CitationBiBTeX, EndNote, RefManPatent Citations (11), Referenced by (18), Classifications (9), Legal Events (4) External Links: USPTO, USPTO Assignment, EspacenetTransmission gearing
US 4756202 AAbstract
A transmission gearing in which an eccentric cam includes first and second eccentric cam parts and a cam follower has contact faces abutting these eccentric cam parts so that, when a driving source rotates either in normal or reverse direction, the gearing provides as an output one of two different directional motions at the cam follower, with either one of the first and second eccentric cam parts positioned concentric with their pivot shaft without shifting the cam itself in diametral direction in gearing casing. The gearing arrangement is thereby simplified and minimized in required mounting space so as to realize a high compactness of the gearing.
1. A transmission gearing comprising:a reversible driving source, eccentric cam means including first and second cam parts driven in rotation by said driving source for selectively generating either of first and second differently directed motions, pivot shaft means for rotatably supporting said cam means, a cam follower having first and second contact faces abutting said first and second cam parts, respectively, positioning means interposed between said driving source and said cam means for positioning said cam means in a first orientation wherein one of said cam parts is concentric with said pivot shaft means and the other of said cam parts is eccentric with said pivot shaft means in a normal directional rotation of said cam means, and for positioning said cam means in a second orientation wherein said one cam part is eccentric with said pivot shaft means and said other cam part is concentric with said pivot shaft means in a reverse directional rotation of said cam means as driven by said reversible driving source, and means coupled to said cam follower for providing one of said first and second differently directed motions as an output obtained through the one of said contact faces which abuts the cam part positioned eccentric to the pivot shaft means. 2. A transmission gearing according to claim 1, wherein said positioning means comprises at least one gear directly driven by said driving source, and an eccentric cylindrical part fixedly coupled to said gear and operatively coupled to at least one of said first and second cam parts of said eccentric cam means.
This invention relates to transmission gearings and, more particularly, to a transmission gearing which can selectively convert a rotational motion to one of two different directional motions, for example, linearly reciprocating and rotatively reciprocating motions.
This sort of transmission gearing is disclosed in U.S. Pat. No. 3,524,088 to William D. Ryckman, Jr., in which a cam is screwedly mounted to a hub of a face gear meshing with an output shaft of a rotary power source so as to be moved in diametral direction of a casing, and is formed to have three cam regions two of which are made differently eccentric, and a cam follower secured to an output shaft of the gearing is provided with cam following elements which can abut the respective cam regions of the cam for selective change of output motion. According to this transmission gearing, the cam to which a rotational force is transmitted from the power source is selectively shifted in the diametral direction of the casing with respect to the cam follower positioned on the axial line of the casing so as to couple the three different cam regions through the cam following elements of the cam follower to the output shaft, for achieving the linearly and rotatively reciprocating motions.
A primary object of the present invention is, therefore, to provide a transmission gearing which can minimize an occupation space of required constituent members for achieving the two different directional motions, and can simplify their arrangement to allow the gearing to be made compact and inexpensive.
FIG. 1 is a perspective view as disassembled of major parts of a transmission gearing in an embodiment according to the present invention;
Referring to FIGS. 1 to 8, a transmission device includes a reversible rotary driving source 11 having an output shaft 12 carrying an output pinion 13 fixedly mounted thereto. A face gear 14 meshes with the pinion 13 and is rotatably mounted axially on a pivot shaft 17 secured at both ends to a chassis 16 provided within a casing 15. On the same side having peripheral gear teeth 18, the face gear 14 is provided with an integral eccentric cylindrical part 20 having an axial bore 19 through which the pivot shaft 17 is passed. The axis of this bore 19 is made eccentric by an eccentricity r1 with respect to the axis of the face gear 14 or cylindrical part 20, and the cylindrical part 20 is provided at a remote end edge from the face gear 14 with an arcuate guide recess 21 extending circumferentially by about 180 degrees. Rotatably mounted on the cylindrical part 20 over its full axial length is an eccentric cam 22 which has a through hole 23 the axis of which is eccentric by an eccentricity r2 with respect to that of the face gear 14 or cylindrical part 20.
Explanation will now be made as to the operation of the transmission gearing of the present embodiment. When such a driving source 11 as a reversible motor is rotated in normal direction, its rotational driving force is transmitted through the output shaft 12 and pinion 13 to the face gear 14 to rotate it about the shaft 17 with the eccentric cylindrical part 20 rotated in a direction of an arrow x in FIG. 4, whereby an end wall of the guide recess 21 abuts the stopper 26 of the eccentric cam 22 to rotate it in the direction x. Under this condition of the eccentric cam 22, the foregoing eccentricities are so set that an eccentricity r5 of the axis of the first eccentric cam region 24 with respect to that of the pivot shaft 17 will be here the sum of r1 and r3 (=2r1 because r1=r3), while an eccentricity r6 of the axis of the second eccentric cam region 25 with respect to that of the pivot shaft 17 will be here the difference between r1 and r2, i.e., zero so that the second cam region 25 will be concentrical with the pivot shaft 17. Therefore, when the face gear 14 and eccentric cylindrical part 20 are rotated in the direction x to cause the eccentric cam 22 rotated as interlocked therewith through the stopper 26, the first eccentric cam region 24 is rotated with the eccentricity r5, which rotation is followed by the cam follower 28 in the sequence shown in FIGS. 6(a) to 6(d). More specifically, the first eccentric cam region 24 is rotated in the cavity 31 of the cam follower 28 with the eccentricity r5=2r1, only linear reciprocating component of this eccentric rotation is transmitted through the first pair of contact faces of the projections 32 and 32a to the cam follower 28, and the output shaft 30 axially linearly reciprocates up and down with a stroke 2r1�2=4r1.
Referring next to the operation of the transmission gearing of this embodiment, a normal directional rotation of such driving source 111 as a reversible motor transmits its rotational force through an output shaft 112 of the driving source and the pinion 113 to the face gear 114 and also to the intermediate gear 135, upon which the both stoppers 126 and 140 of the first eccentric cam part 124 and intermediate gear 135 abut respectively one end wall of the guide recesses 121 and 143 of the eccentric cylindrical part 120 and second eccentric cam part 125 so that the first and second eccentric cam part 124 and 125 will be in interlocking engagement with the face gear 114 and intermediate gear 135, respectively. In this engagement, an eccentricity r15 of the first eccentric cam part 124 with respect to the axis of the pivot shaft 117 is made to be the sum of r11 and r12, i.e., 2r11 because r11=r12, while an eccentricity r16 of the second eccentric cam part 125 is made to be the difference between r13 and r14, i.e., zero so as to be concentrical with the axis of the gear 135. As a result, a linearly reciprocating motion component in the rotation of the first cam part 124 only is transmitted through the projections 132 and 132a to the cam follower 128 so that the output shaft 130 performs a vertically linear reciprocating motion with a stroke of 2r11 �2=4r11.
When the driving source 111 is rotated in the reverse direction, on the other hand, the reverse rotation of the face gear 114 and intermediate gear 135 causes the stoppers 126 and 140 of the first eccentric cam part 124 and intermediate gear 135 to abut respectively the other end wall of the guide recesses 121 and 143, whereby the first and second eccentric cam parts 124 and 125 are brought into reverse directional interlocking with the face gear 114 and intermediate gear 135 to change over the eccentricity relationship by about 180 degrees. Under this condition, the eccentricity r15 of the first eccentric cam part 124 now becomes the difference between r11 and r12 to be zero, while the eccentricity r16 of the second eccentric cam part 125 becomes the sum of r13 and r14 to be thus 2r13 or 2r14. As a result, the second eccentric cam part 125 is rotated at the eccentricity r16=2r14 as held between the forked interlocking arms 133 and 133a so that only rotatively reciprocating component of this rotation is transmitted through the interlocking arms 133 and 133a to the cam follower 128 with a rotational angle of 2θ as seen in FIG. 13, whereby the output shaft 130 executes rotatively reciprocating motion in a range of the angle 2θ.
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