Electric motor driven pump

Abstract: The present invention provides an electric pump apparatus which can be assembled easily by providing a groove having a shape corresponding to that of an opening of a bottomed-cylindrical tank cylinder on pump side end surface of a bracket for supporting the pump and electric motor on its both ends so that the tank cylinder constitutes a reservoir for operating fluid, detachably attaching an opening-side-end portion of the tank cylinder into the groove, and engaging a snap ring with a side wall of the groove; and which is designed to be compact in which a suppression chamber for pulsation-reduction of discharged fluid is integrally provided, by constituting the suppression chamber with the opening side of the groove is sealed by an intermediate plate provided in-between the opening side and pump.

Description: BACKGROUND OF THE INVENTION The present invention relates to an electric pump apparatus, particularly concerns such an electric pump apparatus made to be a compact for vehicle-mount, which has a reservoir for storing operating fluid, the reservoir has a constitution in which an electric motor serving as a driving source is integrally attached on one side of a pump via a bracket, a opening-side-end portion of a tank cylinder is secured on the pump-supporting surface of the bracket so as to surround the pump. In recent years, automobiles are equipped with various hydraulic-actuating devices, such as a power steering apparatus and automatic transmission apparatus, which are actuated by oil pressure to assist driving operation. Accordingly, pumps which generates oil pressure for these hydraulic-actuating devices are also equipped. This type of the pumps are generally driven by engine as a driving source; however, since engine widely changes its rotational speed while traveling, engine is not quite appropriate for the driving source. When engine is used as the driving source, various problems arise in which power-consumption for driving the pump causes an increase in fuel-consumption rate, and furthermore mounting position of the pump could be limited due to obtaining transmission from the engine. For these reasons, in recent years, electric pump apparatuses, which use an electric motor as a driving source that is driven by power supply from a car-mounted battery instead of the engine, have been replacing the engine-driven-pump apparatuses. Meanwhile, electric vehicles (EVs) have been developed in order to prevent environmental deterioration due to exhaust gases, because the EV use an electric motor for the driving source instead of engine. Even the EVs may be mounted with hydraulic-actuating devices, therefore electric pump apparatuses using electric motors as driving sources are inevitably applied with respect to generation sources of oil pressure for such hydraulic-actuating devices. Furthermore, with respect to the electric pump apparatuses of this type, compactness is strongly demanded in order to improve the mountability onto vehicles. Japanese Laid-Open Patent Application No. 10-82377 (1998) by the applicant of the present invention has disclosed an electric pump apparatus in which: a pump is supported on one side of a bracket with an electric motor being supported on the other side, and both of these are connected at the axal portion of the bracket while a bottomed-cylindrical tank cylinder being secured on the pump-supporting surface of the bracket so as to surround the pump, and thus a reservoir for storing operating fluid is constituted, furthermore, mountability onto vehicle is enhanced by integrating the reservoir and electric motor with the pump. Here, in the above-mentioned electric pump apparatus disclosed in Japanese Laid-Open Patent Application No. 10-82377 (1998), securing of the tank cylinder is achieved by allowing a flange circumferentially provided on its opening-side-end portion to contact the supporting surface of the bracket and fastening them together with a supporting flange of the electric motor being contacted to the other surface of the bracket by a plurality of securing bolts placed along the circumferential direction. However, the problem with the electric pump apparatus is that the assembly including this securing process is very complex. Here, in the case when the electric pump apparatus constructed as described above is mounted on a vehicle, so-called "longitudinally-aligned arrangement" in which a pump shaft (input shaft) of the pump is longitudinally connected with a motor shaft (output shaft) of the electric motor is mainly adopted. In some cases for types of vehicle having a limitation of their mounting position, so-called "transversally-aligned arrangement" in which the both shafts are transversally connected may be adopted. In order to make it applicable to both types, two types of tank cylinders are prepared: one is for longitudinal application in which an oil filler port for operating fluid is opened on bottom surface that faces up when mounted, and the other is for transversal application in which similar oil filler port is opened on circumferential surface, and either of these types will be selected depending on the alignment type. However, if the assembly has been carried out with an incorrect selection, the tank cylinder can not be removed solely, and thus the assembly including the installation of the electric motor has to started over. Moreover, the above-mentioned tank cylinder is made out of a thin cylindrical body, therefore it tends to be damaged due to various reasons while in-use. When a replacement of the tank cylinder is required due to such a damaged, a complex task including adjustments of assembly of the electric motor which needs to be removed together with the tank cylinder will also be required. Therefore, replacement on assembly basis including the pump and electric motor is conventionally conducted instead of on part basis; this causes an increase in costs required for the replacement. Here, the pump in the electric pump apparatus constituted as described above is provided as a rotational volume type such as a gear pump or vane pump. In the pump of this type, since intermittent discharging are carried out in response to the rotation of rotors, it is not avoidable to have the discharging oil without containing pulsations. Therefore, this results in disadvantages such as damages in the piping system on discharging side and generation of noises. These pulsations are generated mainly with a frequency corresponding to the product between rotational rate of the rotors and the number of discharges per rotation. For this reason, the pulsations are effectively reduced by placing an accumulator having its inner volume corresponding to this frequency in a halfway of the piping system on the discharging side. However, in the car-mounted electric pump apparatus, it is difficult to mount the accumulator in the halfway of the piping system in the most of the cases. Therefore, in the aforementioned electric pump apparatus disclosed in Japanese Laid-Open Patent Application No. 10-82377 (1998), a suppression chamber having the aforementioned inner volume is constructed inside a reservoir formed on the other side of the pump, and this suppression chamber is used as an accumulator by communicating it with the discharging side of the pump, and thus pressure fluid whose pulsations have been reduced while passing through the suppression chamber is sent out to the discharging side. As described above, the electric pump apparatus disclosed in Japanese Laid-Open Patent Application No.10-82377 (1998) has a constitution in which the driving electric motor and reservoir are integrally formed with the pump. Moreover, the apparatus also has a constitution in which the pulsations on the discharging side is reduced by having the suppression chamber as an integral part; thus, it is very easy for car application. However, the comparatively bulky suppression chamber that requires a predetermined inner volume as described above is placed together with the reservoir on the other side of the pump (on the opposite side to the mounting side of the electric motor), and the electric motor, pump, suppression chamber, and reservoir are aligned in the shaft direction. Therefore, this constitution limits a reduction of the entire size of the apparatus in the shaft direction, and thus it does not sufficiently meet the demand of compactness for car-mount-use. EP 819 854 discloses an electric pump apparatus having the features recited in the preamble of appended claim 1. US 5 084 162 discloses a snap ring used for detachably mounting a filter cartridge assembly on a base. BRIEF SUMMARY OF THE INVENTION The present invention has been devised to solve the above-mentioned problems, and one of the objectives of the present invention is to provide an electric pump apparatus integrally having a reservoir with a pump and electric motor, by adopting a supporting configuration in which a tank cylinder, which constitutes a reservoir for storing operating fluid, is solely detachably attached to a bracket for supporting the pump and electric motor; thereby simplifying its assembly, enabling for replacement of the tank cylinder alone. The electric pump apparatus of the present invention is characterized as claimed in appended claim 1. In the present invention, the groove having a shape corresponding to the opening end of the tank cylinder is provided on one surface of the bracket to which the tank cylinder is secured for constituting the reservoir, the opening-side-end portion of the tank cylinder is fitted into the groove, and this fitting portion is engaged with the anti-come-off ring being engaged with the side wall of the groove so as to secure to the groove without coming off lose. This secured condition is easily cancelled without giving an adverse effect on the securing of the electric motor, by removing the anti-come-off ring, and pulling the opening-side-end portion of the tank cylinder out from the groove. In this invention, when the fitting portion, provided to the opening edge of the tank cylinder, is fitted into the groove having a width corresponding to the thickness of the fitting portion, the inlet surface thinner than the fitting portion is made to be facing against the side wall of the groove with a predetermined gap. therefore, the anti-come-off ring is easily introduced through this gap. Moreover, the anti-come-off ring introduced as described above is further introduced into its engaging position along the inclined guide surface continuously provided with the guide surface, and the tank cylinder is firmly secured without coming off from the groove by contacting the anti-come-off ring to the curved engage surface continuously provided with the guide surface. Moreover, another electric pump apparatus of the present invention is characterized in that the anti-come-off ring is a snap ring having a circular cross-section. In this invention, the snap ring having a circular cross-section is used as the anti-come-off ring. Therefore, mounting of the anti-come-off ring in-between the groove provided in the bracket and the tank cylinder fitted into the groove can be easier. Moreover, still another electric pump apparatus of the present invention is characterized by comprising a biasing member which is intervened between the opening edge of the tank cylinder and the bottom surface of the groove, and which biases the tank cylinder to a direction away from the bottom surface, and thus the biasing member pushes the engage surface onto the anti-come-off ring. In this invention, the biasing member, intervened between the bottom surface of the groove provided to the bracket and the opening edge of the tank cylinder fitted in-to the groove, presses the tank cylinder in a direction away from the bottom surface of the groove, and thus the tank cylinder is held at secured state. Therefore, tilting of the tank cylinder within a mounting gap, caused by the effect of weight of operating fluid stored inside the tank cylinder, is prevented when used in the "transversally-aligned arrangement", for example. The above and further objects and features of the invention will more fully be apparent from the following detailed description with accompanying drawings. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS FIG. 1 is an exploded side view showing an essential part of the first embodiment of an electric pump apparatus according to the present invention; FIG. 2 is a lateral cross-sectional view taken along line I-I of FIG. 1; FIG. 3 is an enlarged cross-sectional view showing proximity of securing section of a tank cylinder shown in FIG. 1; 1; FIG. 4 is an explanatory drawing showing a sequence of securing procedures of the tank cylinder shown in FIG. 1; FIG. 5 is an exploded side view showing an essential part of the second embodiment of an electric pump apparatus according to the present invention, which is used in "transversally-aligned arrangement"; FIG. 6 is an enlarged cross-sectional view showing proximity of securing section of the tank cylinder shown in FIG. 5. DETAILED DESCRIPTION OF THE INVENTION Referring to Figures, the following description will discuss embodiments.of the present invention in detail. (Embodiment 1) FIG. 1 is an exploded side view showing an essential part of the first embodiment of an electric pump apparatus according to the present invention; and FIG. 2 is a lateral cross-sectional view taken along line I-I of FIG. 1. In the electric pump apparatus of the first embodiment, a bracket 2 having a short cylindrical shape, which has one surface side on which a pump 1 is supported, has the other surface side to which a driving-use electric motor 3 is attached. A pump shaft 10 serving as an input shaft to the pump 1 and a motor shaft 30 serving as an output shaft of the electric motor :3 are co-axially aligned inside the bracket 2, and coupled together by a fit-in-type coupling 4. Thus, the driving force of the electric motor 3 taken out by the motor shaft 30 is transmitted to the pump shaft 10 through the coupling 4 so as to drive the pump 1. The pump 1, which is a known gear pump, is placed inside a cavity portion (gear chamber) with an elongated-circle cross-section, formed in a housing 11, so as to allow a driving gear 12 and driven gear 1:3 to engage with each other. Operating fluid, inside of a suction chamber 18 (see FIG. 2) that is provided on one side of this engaging section, is pressurized while being transported in a sealed state between the respective gear teeth and inner circumferential surface of the cavity portion due to rotation of the gears 12 and 13, and discharged into an outlet chamber (not shown) provided on the other side of the engaging section. Here, in FIG. 1, the driven gear 13 is shown as its one portion being overlapped by the driven gear 12 located on the front side of the drawing paper surface. The driving gear 12 and driven gear 13 are rotatably supported at their both ends by a pair of side plates 14 that are insertedly fitted into the cavity portion of the housing 11 from both sides of the gears, while being maintained in the above-mentioned engaging state. The pump 1 arranged as described above, which allows one-side-end surface of the housing 11 to contact the supporting surface of the bracket 2, is secured to the end surface of the bracket 2 by fastening a plurality of securing bolts 16 (four bolts are shown in FIG. 2) arranged along the circumferential direction, together with an end plate 15 overlapped on the other-side-end surface. The pump shaft 10, fitted into the axial center of the driving gear 12, is allowed to penetrate through one of the side plates 14 toward the bracket 2 side, and connected to the motor shaft 30 of the electric motor 3 via the coupling 4. Therefore, with respect to the pumping movement by the pump 1 is carried out in which: rotation of the electric motor 3 is transmitted to the driving gear 12 through the motor shaft 30, coupling 4, and pump shaft 10 in that order, so that the driving gear 12 rotates within inner cavity portion of the housing 11, together with the driven gear 13 in mesh therewith. A tank cylinder 5, which consists of a thin plate member having a bottomed cylindrical shape, has its opening-side-end portion attached to the bracket 2 for supporting the above-mentioned pump 1 so as to surround the pump 1. In other words, a reservoir R for storing operating fluid is formed inside the tank cylinder 5. One of the features of the electric pump apparatus of the present invention lies in its securing structure of the tank cylinder 5. FIG. 3 is an enlarged cross-sectional view showing proximity of the securing section of the tank cylinder 5 shown in FIG. 1. As illustrated in FIGS. 1 and 3, on one side surface of the bracket 2, to which the pump 1 is supported, a groove 26a having a circular shape on its plan view that corresponds to the opening edge of the tank cylinder 5 is circumferentially provided so as to surround the pump 1. The above-mentioned tank cylinder 5 has its opening-side-end portion fitted into the groove 26a, with this fitting portion contacting a snap ring 27 engaging with outside side wall of the groove 26a so as be secured without coming off from the groove. FIG. 4 is an explanatory drawing showing a sequence of securing procedures of the tank cylinder 5 shown in FIG. 1. The tank cylinder 5 is provided with a fitting portion 51a, inlet surface 51b, guide surface 51c, and engage surface 51d. The fitting portion 51a is formed so as to have a thickness approximately equal to width of the groove 26a over an appropriate length from the opening edge of the tank cylinder 5. The inlet surface 51b has a thickness made to be thinner than the fitting portion 51a, and is formed on the side away from the opening edge. The guide surface 51c is located between the inlet surface 51b and fitting portion 51a so as to outwardly inclined toward the opening edge. The engage surface 51d has a curved surface continuously formed with the guide surface 51c. The tank cylinder 5 having the above-mentioned arrangement is supported with the fitting portion 51a on the opening edge side thereof being tightly fitted into the groove 26a, and secured in this state. Here, as illustrated in FIG. 4, the input surface 51b is allowed to face side wall of the groove 26a with a predetermined gap, and the guide surface 51c continuously formed and the engage surface 51d are continuously formed with a semi-circle engagement groove 26b formed on the side wall of the groove 26a so as to engage with the snap ring 27. The snap ring 27 is a sort of snap-on-type stop ring having a circular cross-section, cut at one place on its circumferential direction so as to have C-shape, and thus it is allowed to reduce in its diameter by closing the notched width. This snap ring 27 is introduced into the gap between the inlet surface 51b and side wall of the groove 26a while that diameter-reduced condition, and as indicated by a two-dot-chain line in FIG. 4, is further pushed into the inner side along the gap. This pushing can be securely carried out along the inlet surface 51b which faces in approximately parallel to the side wall of the groove 26a. Upon reaching the guide surface 51c continuously formed with the inlet surface 51b, the pushed-in snap ring 27 is guided outwardly along the inclined slope of the guide surface 51c while expanding diameter by its own elasticity and allowed to engage the engagement groove 26b; thus, it comes into contact with the engage surface 51d formed as a curved surface as described above. Consequently, the tank cylinder 5 is secured with the fitting portion 51a fitted into the groove 26a being prevented from coming off by the snap ring 27. Here, the engage surface 51d formed as the curved surface is contacting the snap ring 27 serving as an anti-come-off ring at one point on its curved surface. Therefore, a reaction force, indicated by an arrow in FIG. 4, is exerted on the snap ring 27 from the contact point outward in the radial direction, that is, in a direction so as to strengthen engagement to the engagement groove 26b. Consequently, the tank cylinder 5 is securely clamped in the above-mentioned secured state. On inner surface of the fitting portion 51a of the tank cylinder 5 is circumferentially provided with a notched portion 51e which has a rectangular cross-section. The opening edge of the tank cylinder 5 is tightly sealed with an 0-ring 81 intervened in the annular gap between the notched portion 51e and groove 26a. Therefore, the operating fluid stored inside the tank cylinder 5, that is, inside the reservoir R, is prevented from leaks. The tank cylinder 5 secured as described above is provided with, as illustrated in FIG. 2, a return opening which penetrates through the circumference wall of the tank cylinder 5 and which opens on the inner surface thereof at one position along the circumferential direction. This return opening is connected to an oil transporting end, not shown, through a return pipe 5a that is provided on the tank cylinder 5 in an outwardly protruding manner so that returned oil from the oil transporting end is returned to the reservoir R via the return pipe 5a. Moreover, a flow-dividing plate 6 is attached to inside of the tank cylinder 5 so as to face the return opening at end of the return pipe 5a. This flow-dividing plate 6 is a plate member curved along the inner surface of the tank cylinder 5, and is provided with a flow-dividing protrusion 60 having a triangle cross-section that is protruded toward the return opening, in the approximately central portion. On one half portion of the flow-dividing plate 6 connecting to one side having this flow-dividing protrusion 60, a plurality of oil-returning perforations 61, which penetrate the circumference thereof, are formed, and on the other half portion of the flow-dividing plate 6 connecting to the other side, guide-out tubes 62 are formed on the end portion in parallel with each other. As illustrated in FIG. 2, to a pump 1 placed inside the tank cylinder 5 is connected a suction tube 18a that communicates with a suction chamber 18 inside the housing 11. The suction tube 18a is a pipe or hose that radially outwardly protrude from the housing 11, and is curved along the inner surface of the tank cylinder 5. The tip portion of the guide-out tube 62 is inserted into the suction tube 18a that opens along the circumferential direction of the tank cylinder 5. Here, the returned oil from the oil-feed destination through the return pipe 5a as described above collides with the flow-dividing protrusion 60 and is divided into two flows as indicated by arrows in FIG. 2. The returned oil that has been divided to one side (right side in FIG. 2) is returned to the tank cylinder 5 through the respective oil-returning perforations 61. The other portion of the returned oil that has been divided to the other side (left side in FIG. 2) is allowed to flow along the annular space between the inner surface of the tank cylinder 5 and the flow-dividing plate 6, and guided out to the suction tube 18a through the guide-out tube 62, and then directly sucked into the suction chamber 18 of the pump 1 together with operating fluid that is introduced from the reservoir R through the rest of the openings of the suction tube 18a. Therefore, the operating fluid stored in the reservoir R is sucked into the suction chamber 18 through the suction tube 18a. Together with this, one portion of the returned oil that has been returned through the return pipe 5a from the oil-feed destination is divided by the flow-dividing plate 6, and introduced into the suction chamber 18 through the guide-out tube 62 with predetermined pressure and velocity. With this arrangement, the flow on the suction side is stabilized so that the generation of cavitation can be reduced. The operating fluid, sucked into the suction chamber 18, is pressurized due to rotation of the driving gear 12 and driven gear 13 as described earlier, and discharged into an outlet chamber, not shown, that is formed on the other side of the suction chamber 18. A suppression chamber 21 having a predetermined inner volume is formed in the bracket 2 as an annular chamber that surrounds the connecting section between the pump shaft 10 and motor shaft 30. The outlet chamber of the pump 1 is allowed to communicate with the suppression chamber 21. Moreover, at one portion of the outer circumference of the bracket 2, an outlet base 64 is provided in a protruding manner as shown in FIG. 2, and a connecting port 63 that opens in the center of this outlet base 64 is allowed to communicate with the suppression chamber 21 inside the bracket 2. With the above-mentioned arrangement, the discharged oil from the pump 1 is once introduced into the suppression chamber 21, and then sent out to the oil-feed destination, not shown, through the connecting port 63. In this case, the suppression chamber 21 is allowed to absorb pulsating components of the discharged oil that is introduced from the outlet chamber of the pump 1, thereby making it possible to reduce pulsations of the discharged oil from the outlet hole. The pulsating components of the discharged oil have a frequency, as its main component, that corresponds to a product between the number of rotations of the driving gear 12 and driven gear 13 serving as rotors and the numbers of teeth of the driving gear 12 and driven gear 13 that become the number of discharges per rotation. Thus, based upon that product, the inner volume of the suppression chamber 21 is properly determined so that it becomes possible to effectively absorb the above-mentioned pulsations. (Embodiment 2) The electric pump apparatus shown in FIG. 1 is designed to be used for the "longitudinally-aligned arrangement" in which the shaft directions of the pump 1 and electric motor 3 are aligned longitudinally, and an oil filler port 53 for operating fluid is provided on the bottom surface of the tank cylinder 5 facing upward. However, as illustrated in FIG. 5, the present invention is also applicable to an electric pump apparatus used for the "transversally-aligned arrangement" in which the shaft directions of the pump 1 and electric motor 3 are aligned transversally. FIG. 5 is an exploded side view showing an essential part of the second embodiment of an electric pump apparatus according to the present invention, which is used for the "transversally-aligned arrangement." With respect to the entire constitution of this electric pump apparatus, the oil filler port 53 for supplying operating fluid into the reservoir R is formed on circumferential surface of the tank cylinder 5 so as to face upward. Except this arrangement, the electric pump apparatus of the second embodiment is similar to the electric pump apparatus of the first embodiment shown in FIG. 1; therefore, the same reference numerals are used for similar members and the detailed description of the other arrangements and functions is omitted. Here, in FIG. 5, illustrations of the return pipe 5a and flow-dividing plate 6 are omitted. As shown in the electric pump apparatus of FIG. 5, similar constitution is adopted in which: the opening-side-end portion of the tank cylinder 5 is fitted into the groove 26a circumferentially provided on the corresponding surface of the bracket 2, with the snap ring 27 being engaged by the groove 26a so as to prevent the tank cylinder 5 from coming off. However, in the case when the "transversally-aligned arrangement" as shown in the Figure is adopted, operating fluid stored inside the reservoir R is held still as indicated by its fluid surface shown in FIG. 5. Therefore, a rotational moment corresponding to weight of the operating fluid is exerted on secured portion of the tank cylinder 5, with the result that the tank cylinder 5 might tilt within a range of the fitting gap between the fitting portion 51a and groove 26a. FIG. 6 is an enlarged cross-sectional view showing proximity of securing section of the tank cylinder 5 in the "transversally-aligned arrangement" shown in FIG. 5. As illustrated in FIG. 6, on the fitting portion 51a of the tank cylinder 5, in similar manner to the notched portion 51e on its inner surface, a notched portion 51f having a rectangular cross-section is also circumferentially provided on its outer surface, and an O-ring 82 is intervened in the annular gap between the notched portion 51f and groove 26a. This O-ring 82 is, different from the sealing-use O-ring 81 intervened in the annular gap between the notched portion 51e and groove 26a, is intervened with a predetermined pressure being applied thereto between it and the bottom surface of the groove 26a. In other words, the O-ring 82 is pushing the fitting portion 51a of the opening end of the tank cylinder 5 to a direction away from the bottom surface of the groove 26a, pressing the engage surface 51d continuously formed with the fitting portion 51a against the snap ring 27 so that the clamping of the fitting portion 51a is strengthened. Thereby, probable tilting of the tank cylinder 5 caused by the above-mentioned rotational moment can be prevented, and thus it becomes possible to ensure a securing state even for the "transversally-aligned arrangement." Here, the above-mentioned strengthening of the clamping by intervention of the O-ring 82 is effective even for the "longitudinally-aligned arrangement." Therefore, the securing constitution shown in FIG. 6 may of course be applied to the electric pump apparatus for use in the "longitudinally-aligned arrangement" as shown in FIG. 1. Moreover, instead of the above-mentioned O-ring 82, other biasing members, such as elastic rings having other forms and various types of springs, may be used so as to bias the opening end of the tank cylinder 5 in a direction away from the bottom surface of the groove 26a. Furthermore, in the above-mentioned embodiment, the snap ring 27 having a circular cross-section is used as an anti-come-off ring for clamping the opening-side-end portion of the tank cylinder 5 that engages the groove 26a of the bracket 2 and is fitted into the groove 26a, so as not to come off; however, other type of the anti-come-off rings having different shapes may be used as long as it exerts the same functions. The above-mentioned embodiments have dealt with hydraulic-type electric pump apparatuses which are to be mounted on vehicles so as obtain operating fluid for hydraulic apparatuses such as power steering apparatuses and automatic transmission apparatuses; however, the present invention may of course be applied to electric pump apparatuses other than those used for vehicle-mount pumps, and may be further applied to electric pump apparatuses using fluid other than oil. Furthermore, the pump 1 is not intended to be limited to a gear pump as explained in the above-mentioned embodiments, and may be other pumps of the rotational volume type, such as vane pumps.

Claims: An electric pump apparatus, comprising : a pump (1); an electric motor (3) for driving the pump (1); a cylindrical bracket (2, 2A) for supporting the pump (1) and electric motor (3) on its respective end faces, with a groove (26a) being circumferentially provided to the end surface ; and a bottomed-cylindrical tank cylinder (5) for constituting a reservoir (R) by fitting its opening-side-end portion into the groove (26a) on the pump (1) side end surface of the bracket (2, 2A) so as to surround the pump (1), further comprising : an anti-come-off ring (27) for securing the tank cylinder (5) by engaging the opening-side-end portion of the tank cylinder (5) with a side wall of the groove (26a) so that the tank cylinder (5) does not come off from the groove (26a), and characterized in that the tank cylinder (5) includes : a fitting portion (51a) having a predetermined length from its opening edge with a thickness approximately equal to width of the groove (26a) ; an inlet surface (51b) which is located at a position farther from the opening edge than the fitting portion (51a) and which faces the side wall of the groove (26a) with a gap which allows the anti-come-off ring (27) to be introduced when fitting into the groove (26a) ; a guide surface (51c), which is located between the inlet surface (51 b) and fitting portion (51a), which is outwardly inclined toward the opening edge, and which introduces the anti-come-off ring (27) along the inlet surface (51b) to its engaging position (26b) ; and an engage surface (51d) which has a curved surface continuously provided with the guide surface (51c) and which touches the anti-come-off ring (27) being engaged at the engaging position (26b). The electric pump apparatus according to claim 1, wherein the anti-come-off ring (27) is a snap ring (27) having a circular cross-section. The electric pump apparatus according to claim 1 or 2, further comprising : a biasing member (82), being intervened between the opening edge of the tank cylinder (5) and the bottom surface of the groove (26a), for pushing the engage surface (51d) against the anti-come-off ring (27) by biasing the tank cylinder (5) away from the bottom surface.

Inventors: HAMASAKI YOSHIAKI, IIDA TOSHIO, YAMAZAKI TAKAYASU, HAMASAKI, YOSHIAKI, IIDA, TOSHIO, YAMAZAKI, TAKAYASU, Hamasaki, Yoshiaki, Koyo Seiko Co., Ltd., IIDA, TOSHIO, KOYO SEIKO CO., LTD., Yamazaki, Takayasu, Koyo Seiko Co., Ltd.
Applicants: KOYO SEIKO CO, KOYO SEIKO CO., LTD.
Application year: 1999
Main classification: F04C11
IPC codes: F04C15, F01C21, F04C11