The present invention relates to an electric pump apparatus including, primarily, a pump for generating an oil pressure, and a motor for driving the pump.
The vane pump 101 is driven by the electric motor 102 acting as a drive source to pump out liquid. A coupling 112 mechanically interconnecting a motor shaft 109 and the pump shaft 111 is accommodated in the bell housing 107. Although meshing noise is made from the coupling 112 due to rotation of the motor shaft 109, a soundproof effect of the bell housing 107 prevents transmission of the noise to the outside of the apparatus 100, thereby keeping silence of the outside.
The electric pump apparatus 100 shown in
While there is the demand for effective use of the floor area, it is desirable to reduce the floor area occupied by the electric motor and the tubes.
An object of the present invention is to provide a structure designed such that an electric pump apparatus and tubes occupy a small floor area.
According to an aspect of the present invention, there is provided an electric pump apparatus to be mounted on a machine base having a horizontal mounting surface, the apparatus including a pump for generating an oil pressure, a motor for driving the pump, and a bracket supporting the pump and the motor, wherein the motor is a servo motor with a cooling fan, and the motor comprises: a motor flange connected to the bracket by bolts; a motor shaft disposed horizontally and extending through the motor flange; a rotor mounted on the motor shaft; a stator surrounding the rotor; a motor frame accommodating the rotor and the stator together; a sensor connected to a rear end of the motor shaft; and a fan cover enclosing at least the sensor, the cooling fan being accommodated in the fan cover for air-cooling the motor frame, wherein the bracket comprises: a base portion to be secured to the machine base; and a support plate extending upwardly from the base portion to ensure a gap of a predetermined size between the pump and the mounting surface and a gap of a predetermined size between the motor and the mounting surface, the support plate comprising a pump-side support plate and a motor-side support plate disposed a predetermined distance away from the pump-side support plate.
The pump and tubes overlap and the motor and tubes overlap, as viewed in plan, and hence the electric pump apparatus and the tubes occupy a small floor area.
Further, the support plate comprises the pump-side support plate and the motor-side support plate disposed the predetermined distance away from the pump-side support plate. The pump-side support plate and the motor-side support plate extend upwardly from the base portion. Vibration on a side of the pump is transmitted through the base portion to the motor-side support plate, but is lessened by the base portion because the base portion is secured to the machine base. As a result, the damped vibration is transmitted to a side of the motor.
Preferably, the pump is a flanged axial piston pump, and the pump comprises: a pump flange connected to the bracket by bolts; a pump shaft disposed horizontally and extending through the pump flange; and axial pistons movable in parallel to the pump shaft. The apparatus further comprises a vibration absorbing ring interposed between the support plate and the pump flange for absorbing vibration.
The pump is the axial piston pump. The axial piston pump unavoidably generates vibration in an axial direction of the pump shaft. To address this, the vibration absorbing ring is interposed between the pump flange and the support plate supporting the pump. The vibration absorbing ring eliminates influence of the vibration of the axial piston pump on the motor.
Preferably, the apparatus further comprises a flexible coupling interconnecting the pump shaft and the motor shaft.
The flexible coupling damps the vibration of the pump shaft, and the damped vibration is transmitted to the side of the motor.
Preferred embodiments of the present invention will be described in detail below, by way of example only, with reference to the accompanying drawings, in which:
As shown in
The electric pump apparatus 10 is suitable for a hydraulic injection molding machine. That is, the electric pump apparatus 10 supplies oil under high pressure to a clamping cylinder, an injection cylinder and an injector moving cylinder. The single electric pump apparatus supplies oil to the many cylinders. An amount of oil discharged from the pump greatly varies because the many cylinders operate at different timings. The motor 30 is a servo motor to change a speed of the pump to vary the amount of oil discharged from the pump. The servo motor 30 has an inner structure as will be discussed with reference to
The pump 20 is a hydraulic pump which can be a rotary pump such as a vane pump, a gear pump and a Roots pump. The rotary pump less vibrates in an axial direction of the pump shaft 21.
The motor 30 is the servo motor including a motor flange 33 at a front side thereof, and the motor flange 33 is connected to the bracket 50 by bolts 32. The servo motor also includes the motor shaft 31 disposed horizontally and extending through the motor flange 33.
A general-purpose motor operates continuously at a constant speed during a period of time between activation of the motor and stop of the motor. In contrast, the servo motor 30 is also called a control motor which frequently repeats activation, stop and speed change. An accelerated energy required to accelerate a rotor is mostly consumed by a frictional resistance on a bearing. The same goes for deceleration of the rotor. Thus, the servo motor 30 which is used at a high duty (a high frequency and high load) is desired to have a high cooling performance.
To this end, a fan cover 34 is mounted to the motor with a fan 35 accommodated in the fan cover 34 to perform a forced cooling.
Although various kinds of structures of fans are well-known, the fan 35 preferably employs a fan motor having a structure providing the small overall length of the fan.
That is, the fan motor employed by the fan 35 includes a fan motor frame 35a having impellers 35b mounted thereon, and a fan motor shaft 35c mounted to a stay 36.
More specifically, the stay 36 is disposed in an upright position on the fan cover 34. The fan motor shaft 35c is secured to the stay 36. The fan motor frame 35a and the impellers 35b rotate on the fan motor shaft 35c.
A pair of bearings rotatably supporting the fan motor shaft 35c is incorporated in the fan motor frame 35a.
The bracket 50 is comprised of a base portion 52 secured to the machine base 60 by bolts 51, and a support plate 53 disposed in an upright position on the base portion 52. The support plate 53 has a height dimension set to ensure a gap having a height Hp between the mounting surface 61 and the pump 20 and a gap having a height Hm between the mounting surface 61 and the motor 30.
For example, an oil drawing tube 63 and an oil discharging tube 64 can pass in the gap Hp. A pneumatic pipe 65 and an electric wiring 68 can pass in the gap Hm.
Next, a preferred modification is discussed below with reference to the drawings.
As shown in
The pump 20 is a flanged axial piston pump. That is, the pump includes a pump flange 23 at a front side thereof and the pump flange 23 is connected to the bracket 50 by bolts 22. The pump 20 also includes the pump shaft 21 disposed horizontally and extending through the pump flange 23, axial pistons 24, 24 movable in parallel to the pump shaft 21, a swash plate 25 for actuating the axial pistons 24, 24, and a pump case 26 accommodating these elements together.
The axial pistons 24, 24 are provided in a pump rotor 27 and rotated by the pump shaft 21 such that the axial pistons 24, 24 are axially moved by the swash plate 25 to generate an oil pressure. The pump is a reciprocating pump and hence provides a higher oil pressure than that provided by a rotary pump. The axial piston pump is employed depending on an intended purpose.
The reciprocating pump vibrates in the axial direction of the pump shaft 21 much more than the rotary pump does. When this vibration is transmitted to the motor shaft 31, the motor frame 39 vibrates to thereby vibrate the fan cover 34 attached to the motor frame 39, such that the fan motor shaft 35c is vibrated through the stay 36.
As is clear from the figure, the servo motor 30 is supported by the bracket 50 in a cantilever fashion and hence even a small amplitude of the motor flange 33 causes a large amplitude of the fan motor shaft 35c disposed far from the bracket 50. The two bearings supporting the fan motor shaft 35c are small in size and thus inferior in durability, and hence, if the bearings are subjected to the large amplitude, the bearings would reach the end of their useful life in a relatively short period of time.
If large-sized bearings having a prolonged useful life are used, the entire size of the fan 35 would be large, in which case it would be difficult to provide the compact size of the electric pump apparatus 10 and the manufacturing cost of the apparatus would increase.
To meets the need for the compact size of the electric pump apparatus 10 and reduction in the manufacturing cost of the apparatus, the present invention exercises ingenuities discussed below.
First, a structure of the bracket 50 is improved such that vibration on a side of the pump 20 is less likely to be transmitted to a side of the motor 30.
Second, a vibration absorbing ring 70 is interposed between the bracket 50 and the pump 20, such that vibration on the side of the pump 20 is far less likely to be transmitted to the side of the motor 30.
Third, a structure of the coupling 40 is improved.
The three improvements above are discussed in order.
First Improvement: As shown in
Second Improvement: As shown in
The provision of the vibration absorbing ring 70 allows provision of bridges 55, 56 shown by phantom lines. The provision of the bridges 55, 56 increases rigidity of the bracket 50. In
Third Improvement: The coupling 40 is a flexible coupling 40 as shown in
As shown in
The first boss 41 is cut in a direction perpendicular to an axis of the boss to form slits 48, such that a diameter of an axial hole of the first boss 41 is reduced by fastening a first lock bolt 49. The same goes for the second boss 43.
The assembled flexible coupling is shown in cross-section in
As shown in
A motor torque is transmitted from the motor shaft 31 through the first flange 42, the first bolts 46, the leaf spring 45, the second bolts 47 and the second flange 44 to the pump shaft 21 (as indicated by an arrow (1)). In contrast, vibration of the pump shaft 21 is transmitted toward the motor shaft 31 in a reverse route opposite to the route indicated by the arrow (1). Since the flexible leaf spring 45 has a damping performance, the vibration of the pump shaft 21 is damped and transmitted to the motor shaft 31.
Provision of at least one of the foregoing three improvements can address vibration of the fan 35 shown in
Turning to
Although the electric pump apparatus 10 is suitable for the hydraulic injection molding machine, the apparatus 10 can be arranged in other hydraulic circuits.
The flexible coupling 40 may be of any type such as a rubber coupling using a rubber member in place of the leaf spring member.
The electric pump apparatus of the present invention is suitable for the hydraulic injection molding machine.
Obviously, various minor changes and modifications of the present invention are possible in the light of the above teaching. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.
Number | Date | Country | Kind |
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2014-137167 | Jul 2014 | JP | national |
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Machine Translation of Japanese Patent JP 2013060981 A to Hiroshima. |
Notification of Reasons for Refusal dated Sep. 15, 2016 in Japanese Patent Application No. 2014-137167 together with partial English-language translation. |
Notification of Reasons for Refusal dated Jan. 23, 2017, issued in Japanese Patent Application No. 2014-137167 together with English-language translation thereof. |
Number | Date | Country | |
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20160003226 A1 | Jan 2016 | US |