JP2003047220A - Three-phase induction motor and motor integration type fluid pressure generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To save energy with a method which has not yet been proposed by providing a motor which is suitable for the method of driving a fluid pump to select the motor under the maximum load output condition of the cutoff type variable capacity fluid pump, and also by providing a motor integration type fluid pressure generator using the same motor. SOLUTION: This motor is a three-phase induction motor which is in the same frame number and in the same rating as a general purpose standard motor, and assures the efficiency of 74% or more under the actual load condition equal to 25% or more of the rated output and the start/stop torque of 200% or more of the rated output. In addition, the cutoff type variable capacity fluid pump is connected in direct to this three-phase induction motor to form the motor integration type fluid pressure generator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor-integrated fluid pressure generating device in which a cut-off type capacitive fluid pump is directly connected, and more particularly to a three-phase induction motor suitable for such a device.

[0002]

2. Description of the Related Art A general purpose electric motor (three-phase induction motor: hereinafter referred to as an electric motor) has an efficiency of 80 to 85 at a rated output.
% (At actual load), and the efficiency at low load, which is 25% of the rated output, is about 68 to 73%. Regarding the starting torque / stopping torque, JIS C 4210 requires that the output is 1.8 to 2.0 times the rated output.

On the other hand, FIG. 5 shows the discharge flow rate characteristics with respect to the load pressure of the cut-off type variable displacement fluid pump. As shown in FIG. 5, the cut-off type variable displacement fluid pump has a flow rate characteristic that, as shown by the curve A, has a maximum discharge amount at the minimum load pressure, and the discharge amount gradually decreases as the load pressure increases. , The discharge rate becomes zero at the maximum load pressure. Further, the required shaft input characteristic is, as shown by the curve B, a mountain-shaped characteristic having a maximum shaft input value in proportion to the product of the discharge amount and the load pressure. In selecting the output of the electric motor driving the cut-off type variable displacement fluid (hydraulic) pump, the electric motor capacity (kW) is selected from the output at the maximum load. For example, 100 to 150% of the motor output is set to the maximum load. In the example of FIG. 5, the dotted line W indicates 2.2k.
W is the motor output. Alternatively, the motor output is selected from the equivalent capacity in cycle operation. However, when selecting the electric motor, if the selection is made from the output at maximum load in the constant discharge region of the variable displacement type hydraulic pump, there is a problem that the efficiency is poor in the region where the load is low such as at low pressure or full cutoff. In addition, when selecting from the equivalent capacity of the load cycle of the pump, it may be possible to lower the rank of the frame number of the motor output, but if the conditions for cycle operation are not clear, the motor cannot be selected or at the time of instantaneous start. There was also a problem that there was no margin in stopping torque.

[0004]

Therefore, in general,
In many cases, the motor output is selected on the premise that it will be used at maximum load with a margin in mind. However, when the electric motor output is selected based on the maximum load, in the cut-off type variable displacement hydraulic pump, there is a problem that the load factor of the electric motor changes and energy saving cannot be achieved. An object of the present invention is to provide an electric motor suitable for a driving method of such a fluid pump in selecting an electric motor under the maximum load output condition of a cut-off type variable displacement fluid pump, and further to provide an electric motor integrated type using the electric motor. The purpose of the present invention is to provide a fluid pressure generating device and achieve energy saving that has not been available in the past.

[0005]

In the present invention, the same frame number and the same rating as those of a general-purpose standard electric motor are used.
The above problems have been solved by providing a three-phase induction motor having an efficiency of 74% or more at an actual load of 25% or more of the rated output and a starting / stopping torque of 200% or more of the rated output. That is, the start / stop torque is set to 200% or more of the rated output to secure the required energy at the maximum load of the cut-off type variable displacement fluid pump, while the efficiency at 25% of the rated output is 74% or more. By setting the best value of the motor efficiency to the low output side, it is possible to increase the efficiency in a region where the load is low, such as at low pressure or full cutoff, and it is possible to save energy as a whole.

In order to effectively use such a three-phase induction motor, a cut-off type variable displacement type fluid pump is directly connected to the above-described three-phase induction motor of the present invention to provide a motor-integrated fluid pressure generator. Item 2). Since the electric motor and the fluid pump improve the efficiency in the low load region while maintaining the output at the maximum load, the power consumption can be significantly improved in the cycle operation in which the low load condition is long. Further, there is no problem even if the pump and the electric motor are selected by the same selection method as the conventional one, and it is possible to save energy.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of an electric motor-integrated fluid pressure generator showing an embodiment of the present invention, FIG. 2 is a rotor (rotor) of the electric motor showing an embodiment of the present invention, and FIG. FIG. 3 is a perspective view of the (stator), and FIG. 3 is a performance comparison diagram regarding load factor-efficiency of the embodiment of the present invention and the conventional electric motor. As shown in FIG. 1, the electric motor integrated fluid pressure generating device 20 of the present invention is substantially the same as the conventional one, and the hydraulic pump 21 is a front cover portion 2 a of the main body 2 of the electric motor 1.
, The tip 3a of the electric motor shaft 3 is fitted and inserted into the tip hole 22a of the drive shaft 22 of the hydraulic pump, and the hydraulic pump drive shaft is rotated by the rotation of the electric motor shaft to perform a pump action. The electric motor shaft 3 is rotatably supported by two bearings 4 mounted in the electric motor main body 2, and a rotor (rotor) 5 is provided on the electric motor shaft. It is fixed to. A fan 7 for cooling is provided at the rear end of the motor shaft. Reference numeral 8 is a terminal box, 9 is an eyebolt for lifting, 10 is a mounting foot, and these are the same as those of a so-called general-purpose three-phase induction motor.

In the present invention, for example, as shown in FIG. 2A, the product thickness width 12 in the longitudinal direction is 100 mm to 80 m.
The iron loss was suppressed by setting m. Also, the hoop width 1
By setting 3 to 158 mm to 159 mm, the magnetic field is stabilized. As a result, the efficiency is improved in the low load region of the motor, and the efficiency is improved by 9% when the rated output (2.2 kW) is 25%. As for the starting torque, by changing the slot shape 11 from an open slot to a closed slot, Pull-UP
Increase the torque from 135% to 195% (2.2kW-4
(P, 60 Hz, AC200V), the reduction of the starting torque due to the above improvement was suppressed. That is, FIG. 3 shows 2.2 kW-4
The relationship between the load factor of the motor and the efficiency of the motor at P, 60 Hz, and 200 V AC is shown at the actual load.
The efficiency W2 of the conventional general-purpose electric motor shown by the dotted line in FIG. 3 is set so that the electric motor efficiency is maximized at 75% to 100% of the rating, and at 25% load, it is considerably low. Although not shown, the starting torque and the like are also set as large as possible. On the other hand, in the motor of the present invention, the efficiency W1 of the motor is such that the maximum efficiency is about 50% of the load factor, and in particular, the efficiency curve is on the left side in the figure so that the motor efficiency becomes 79% at 25% load. Deviation, the efficiency is improved in the region where the motor load is low. Further, the starting torque and the like at this time have a structure such that 200% or more can be secured.

The hydraulic pump 21 is a vane type variable displacement hydraulic pump. In the hydraulic pump main body 21b, a drive shaft 22 supported by a slide bearing 26, a rotor 27 rotating with the drive shaft, and a plurality of rotors provided on the rotor. A vane 29 that can be moved in and out of the groove 28 and a circular cam ring 30 with which the vane slides are provided. Rotor, vane,
Side plates 31 sandwiching the cam ring so as to be slidable from both sides are provided, each forming a pressure chamber, and a drive shaft 22, (rotor) 27 and circular cam ring 30 are formed by a variable device (not shown).
The eccentricity makes the discharge amount variable. In particular, as shown in FIG. 5 described above, the discharge amount is reduced by the increase of the load pressure, and the discharge amount becomes zero at the maximum load pressure, which is a cut-off type. Such pumps are well known and will not be described in detail.

If the electric motor of the present invention having such characteristics is combined with a cut-off type variable displacement pump, the electric motor can be used with the same electric motor efficiency as before when the electric motor is in the vicinity of the rated output, and in a low load region. , Energy saving compared to conventional general-purpose electric motors. The cut-off type variable displacement hydraulic pump has load characteristics as shown in FIG. 5, as described above. As an electric motor that drives a variable displacement hydraulic pump, the rated output (2.2 kW) of the electric motor is exceeded in region a (mainly full flow rate discharge), so the starting torque and stall above the maximum shaft input of the hydraulic pump. Torque is required, but there is no discharge flow rate, and only the holding pressure is required. The electric motor output near the full cut-off point c is about 25% of the rated output. The load state is used in the area a when the actuator operates on the mother machine side, and in the vicinity of c when the pressure is held by the clamp and chuck. In particular, in cycle operation where the machining time is relatively long such as machine tools, the operating rate is high in the vicinity of c, and even in the variable displacement hydraulic pump, the loss in the vicinity of c is suppressed and the efficiency of the drive side electric motor is improved. As a result, it is possible to save energy on the mother machine side.

[0011]

[Embodiment] By using the fluid pressure generator of the present invention and the conventional electric motor integrated type having the above-mentioned characteristics, the pressure at full cutoff (holding pressure) (point c shown in FIG. 5) is changed to reduce power consumption. Was measured. The result is shown in FIG. As shown in FIG. 4, the power consumption W4 of the conventional product is about 0.58 to 0.75 kW.
In contrast, the power consumption W3 of the product of the present invention is 0.45
The power consumption was reduced to 0.58 kW, which is about 20%. Also,
The motor efficiency at the rated output conventionally used is 80 to 85%, which is the same as that of the general-purpose motor, and there was no problem. Although the vane type pump has been described in the embodiment, it goes without saying that the same applies to a cut-off type variable displacement pump such as a piston type.

[0012]

According to the present invention, the starting / stopping torque is set to 200% or more of the rated output, while the starting / stopping torque is set to 25% of the rated output.
The efficiency of the motor is 74% or more and the best value of the motor efficiency is shifted to the low output side to improve the efficiency on the low load side. Therefore, the cut-off type variable displacement type has a longer operating time at full cutoff than the maximum load. It became suitable for fluid pumps. Also,
It is intended to save energy at low pressure or at full cutoff.

By combining the electric motor and the fluid pump, the power consumption can be greatly improved. On the other hand, the same motor output as that of the conventional variable pump can be selected, and even if the selection is made in the same manner as the conventional one, an energy-saving type can be easily selected only by combining with the motor of the present invention. Also,
Since the motor is not selected based on the equivalent capacity from the cycle operation, there is no need to worry about recalculation due to specification changes or damage to the motor due to overload, etc., and the design can be done easily as before.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a motor-integrated fluid pressure generating device according to an embodiment of the present invention.

2A is a perspective view of a rotor (rotor), and FIG. 2B is a perspective view of a stator (stator) of an electric motor according to an embodiment of the present invention.

FIG. 3 is a performance comparison diagram relating to load factor-efficiency of an embodiment of the present invention and a conventional electric motor, where the horizontal axis represents the motor load factor (%) and the vertical axis represents the motor efficiency (%).

FIG. 4 is a comparative example of power consumption of an embodiment of the present invention and a conventional electric motor-integrated fluid pressure generation device, in which the horizontal axis shows the pressure at full cutoff and the vertical axis shows the power consumption at full cutoff. .

FIG. 5 is a flow rate-load characteristic of a cut-off type variable displacement fluid (hydraulic) pump, where the horizontal axis represents load pressure (MP
a) and the vertical axis is the discharge flow rate (lit / min).

[Explanation of symbols]

1 Three-phase induction motor. 20 Electric motor integrated fluid pressure generator 21 Cut-off type variable displacement fluid pump

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Claims (2)

[Claims] 1. The same frame number as a general-purpose standard electric motor, and
A three-phase induction motor of the same rating, having an efficiency of 74% or more under an actual load of 25% or more of the rated output, and a start / stop torque of 200% or more of the rated output. . 2. A three-phase induction motor according to claim 1, wherein a cut-off type variable displacement fluid pump is directly connected to the three-phase induction motor.