Motor-equipped reduction gear device with a pre-stage

Abstract: In a motor-equipped reduction gear device with a pre-stage, two covers, which have been indispensable in the past, namely a joint cover and a pre-stage cover, are integrated into a one-body cover 130. Also, the diameter D1 of the addendum circle of the pinion 110 mounted on the tip of the motor shaft 108 is designed to be smaller than the diameter D2 of the portion of the motor shaft 108 which extends into the one-body cover 130. This allows the one-body cover 130 to be mounted with the pinion 110 already attached to the tip of the motor shaft 108. The one-body cover 130 can freely and easily be attached to the motor 102 and the gear box 106. As a result, the number of parts is reduced and light weight and compactness are achieved, and accuracy of the center distance and parallelism are improved because cumulative machining errors can be avoided. Furthermore, cost down and improved rigidity are achieved and the number of factors which may causeoil leakage is decreased.

Description: The present invention relates to a motor-equipped reduction gear device having a so called pre-stage. From DE-A-1 023 646 there is known a reduction gear device being constituted by a two-step reduction gear and an electric motor, which is mounted to a side portion of the housing of said reduction gear, via a motor-joint-cover. A bottom portion of the housing of said reduction gear is provided with an opening through which the gearing components of said reduction gear are inserted into the interior space of said housing. From US-A-1 988 338 there is known a geared motor having a reduction gear device which is mounted via a number of connecting bolts to a front cover member of an electric motor. The interior space of the housing of said reduction gear device is accessible via an opening section which is covered by said front cover member of the motor when said motor is mounted to said reduction gear device. From AT-B-0 132 606 there is known a reduction gear device having a housing which is constituted by three housing portions which are mounted together so as to define two gearing chambers, wherein in each gearing chamber there is received a single gearing step constituted by a pair of gear wheels which are mounted on respective support shafts prior to assembly of the respective housing members. From GB-A-0 508 178 there is known a planetary-reduction-gear device having an electricmotor flanged to a rear-side portion of a multi-part housing. It is an object of the present invention to create a motor equipped reduction gear device which has a simplified structure and which can be manufactured at reduced manufacturing costs. According to the present invention this object has been performed by a motor-equipped reduction gear device as defined in claim 1. In the present invention, the joint cover of the motor and the cover of the pre-stage are integrated into one body. In addition to that, the diameter of the addendum circle of the pinion mounted (or direct-cutted) on the tip of the motor shaft is arranged to be smaller than the diameter of the motor shaft portion which extends into the one-body cover. As a result, in addition to integrating the cover into one body, it is possible to pre-connect the pinion, which is to be mounted on the tip of the motor shaft, to the motor shaft. This allows the gear pair of the pre-stage to be freely and easily assembled. That is, the present invention provides an easy assembly, improvement in the rigidity, reduction of oil leakage and achievement of low costs, due to a reduction in the number of parts. Furthermore, since the accuracy of the center distance and parallelism within the pre-stage can be largely maintained, the present invention provides the outstanding effect of giving full play to the original transmission functions of a pre-stage. Further advantageous features and details will become more apparent from the following description in conjunction with the accompanying drawings, wherein like reference characters designate the same or similar parts and wherein: Fig. 1 is a cross sectional drawing showing the pre-stage of the first embodiment according to the present invention, Fig. 2 is a partial cross sectional drawing showing the second embodiment according to the present invention, The preferred embodiments of the present invention will be described in detail hereinunder with reference to the drawings. Fig. 1 shows the first embodiment according to the present invention. In Fig. 1, reference numerals 102, 130 and 106 indicate a motor, a one-body cover and a gear box, respectively. The one-body cover 130 is fixed to the motor 102 and the gear box 106 by bolts 151 and 150, which are provided at appropriate locations. The pre-stage of this embodiment has one gear pair. The diameter D1 of the addendum circle of the pinion 110 mounted on the tip of the motor shaft 108 is set to be smaller than the inner diameter D2 of a sealing member 122 which serves as an oil seal between the one-body cover 130 and the motor shaft 108. (The inner diameter D2 of the sealing member 122 corresponds to the outer diameter of the portion of the motor shaft 108 which extends into the one-body cover 130.) In Fig. 1, reference numerals 112 and 114 indicate a gear in the pre-stage and a pinion in the gear box, respectively. The gear 112 and the pinion 114 correspond to the conventional gear 12 and pinion 14. Furthermore, in Fig. 1, reference numeral 140 indicates a bearing for supporting the motor shaft 108 and reference numerals 142 and 144 indicate bearings for supporting a shaft 113 on which the gear 112 and the pinion 114 are mounted. The bearings 140, 142 and 144 correspond to the conventional bearings 40, 42 and 44, respectively. The function of this embodiment will be described hereinafter. Since the diameter D1 of the addendum circle of the pinion 110 mounted on the tip of the motor shaft 108 is smaller than the inner diameter D2 of the sealing member 122, it is possible to pre-connect (or direct-cut) the pinion 110 to the motor shaft 108. That is, the one-body cover 130 can be attached to the motor 102 with the pinion 110 mounted (or cutted directly) on the motor shaft 108. Also, in this embodiment, since the diameter D3 of the addendum circle of the gear 112 in the pre-stage is smaller than the smallest inner diameter D4 of the mounting hole 146 for the bearing 144, it is possible to assemble the gear 112 from the side of the gear box 106 following the assembly of the one-body cover 130 to the motor 102. However, if the diameter D3 of the addendum circle of the gear 112 is greater than the inner diameter D4 of the mounting hole 146, the one-body cover 130 can be assembled to the motor 102 following the assembly of the gear 112 to the one-body cover 130. Thereafter, the one-body cover 130 can be assembled to the gear box 106 while keeping the pinion 114 in mesh with the first-stage gear 115 in the gear box 106. The rotation of the motor shaft 108 is reduced by means of the gear pair consisting of the pinion 110 and the gear 112. That is, the rotation is reduced by the gear pair of the so-called pre-stage. Then the pre-reduced rotation is transmitted through the pinion 114 to the first-stage gear 115 in the gear box 106. Accordingly, a total speed reduction ratio that is equal to the speed reduction ratio achieved within the gear box 106 multiplied by the speed reduction ratio achieved by the pinion 110 and the gear 112 is obtained. Fig. 2 shows the second embodiment according to the present invention. In this embodiment, the position of the sealing member 222, which serves as an oil seal for the motor shaft 208, and the position of the bearing 240 are reversed with respect to the axial direction. In this case too, as long as the diameter D5 of the addendum circle of the pinion 210 mounted on the tip of the motor shaft 208 is set to be smaller than the diameter D6 of the motor shaft 208, the existence of the bearing 240 which supports the motor shaft 208, and the sealing member 222 does not cause any obstacles, because it is possible to freely pass through the sealing member 222 and the bearing 240 with the pinion 210 mounted on the motor shaft 208. Accordingly, the second embodiment provides the same effect as the first one. Since the rest of the structure and the function are the same as those of the first embodiment, identical parts are denoted by reference numerals the last two digits of which are identical to the last two digits of the reference numerals in Fig. 1. To avoid repetition, a detailed description of the second embodiment is omitted. In the above-described embodiments, the pre-stage comprises a single gear pair. However, actually the pre-stage may comprise more than two gear pairs. According to the embodiments, speed reduction gear device, which in the past required two covers, namely a joint cover and a pre-stage cover, requires only a single one-body cover. Therefore, the number of bolt connections can be decreased and light weight and compactness can be achieved. Furthermore, integration of the pre-stage into the one-body cover eliminates the problem of cumulative machining errors which cause a decrease in the accuracy of the center distance and parallelism of the gear pair in the pre-stage. Also, the occurrence of non-uniform contact between the tooth surfaces of the gear is eliminated. As a result, it is possible to largely maintain the original speed reduction characteristics of a pre-stage for a long period of time. Also, the linkage of the motor and gear box by one member reduces the number of parts, which in turn reduces assembly time and costs. Moreover, rigidity can be largely maintained and oil leakage from between the faces which connect the past joint cover and the past pre-stage cover can be prevented. Incidentally, if the motor and the pre-stage (with built-in gear) are stored as one assembly kit, the assembly kit will be able to provide the function of a low-speed motor.

Claims: A motor-equipped reduction gear device comprising a motor (102) having a motor shaft (108, 208), a gear box (106), and a pre-stage reduction mechanism (110, 112; 210, 212) provided between said motor (102) and said gear box (106) and including a pinion (110, 210) provided on a tip of said motor shaft (108, 208), and a gear (112, 212) mounted on an input shaft (113, 213) of said gearbox (106), said pre-stage reduction mechanism (110, 112; 210, 212) being housed by a one-body pre-stage cover (130, 230) which covers and protects the portion where the motor (102) and the pre-stage reduction mechanism (110, 112; 210, 212) are linked, and which supports said motor shaft (108, 208) and said input shaft (113, 213) for rotation, wherein a diameter (D1, D5) of an addendum circle of said pinion (110, 210) is set so that it is smaller than a diameter (D2, D6) of the motor shaft portion which extends into said cover (130, 230). Motor equipped reduction gear device according to claim 1, wherein the diameter (D1) of the addendum circle of the pinion (110) provided on the tip of the motor shaft (108) is set to be smaller than the diameter (D2) of a sealing member (122) which serves as an oil seal between the one-body pre-stage cover (130) and the motor shaft (108). Motor-equipped reduction gear device according to claim 2, wherein the inner diameter (D2) of said sealing member (122) corresponds to the outer diameter of the portion of the motor shaft (108) which extends into the one-body cover (130). Motor-equipped reduction gear device according to at least one of claims 1 to 3, wherein said pinion (110) is direct-cut in the motor shaft (108). Motor-equipped reduction gear device according to at least one of claims 1 to 4, wherein the diameter (D3) of the addendum circle of said gear (112,212) of the pre-stage reduction mechanism mounted on the input shaft (113, 213) of said gearbox (106) is smaller than the smallest inner diameter (D4) of a mounting hole (146) in said pre-stage cover (130, 230) for a bearing (144,244) which supports said input shaft (113, 213) for rotation. Motor-equipped reduction gear device according to at least one of claims 1 to 5, wherein said pre-stage reduction mechanism is constituted by said pinion (110,210) and said gear (112, 212), wherein said gear (112,212) being supported by a pair of bearings (144,244;142,242) supported by said pre-stage cover (130, 230). Motor-equipped reduction gear device according to claim 5, which is such that said gear (112) in the pre-stage can be assembled from the side of the gear box (106) following to the assembly of the one-body pre-stage cover (130,230) to said motor (102).

Inventors: CHIBA YOSHIKAZU, LACHENMAIER SEPP G, SHINODA HIROYUKI, STAPELFELDT THOMAS, CHIBA, YOSHIKAZU, LACHENMAIER, SEPP G., SHINODA, HIROYUKI, STAPELFELDT, THOMAS
Applicants: SUMITOMO HEAVY INDUSTRIES, SUMITOMO HEAVY INDUSTRIES, LTD.
Application year: 1992
Main classification: F16H57
IPC codes: F16H1, F16H57