JP2015180173A - Mechanical apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maximize the effect of reduction in power consumption when a high efficiency induction motor is used.SOLUTION: In changing a conventional induction motor to a high efficiency induction motor, the reduction ratio of a reduction gear is increased so that a mechanical apparatus provides the same rotational speed as that available when the conventional induction motor is used, thereby allowing the mechanical apparatus to provide the same output as that provided when the conventional induction motor is used, and increasing the reduction ratio by 1.0% or more and 6.0% or less in accordance with an increase of the rotational speed. This permits the mechanical apparatus such as a pump or fan to be operated under the same load conditions as those required when the conventional induction motor is used. It is thus possible to maximize the effect of reduction in power consumption by increasing the efficiency of the motor.

Description

  The present invention relates to a mechanical device.

  Conventionally, induction motors are used in various mechanical devices such as pumps, blowers (fans), and compressors in order to reduce and reduce energy consumption, and the induction motor itself aims to further reduce power consumption. Development of high efficiency and control methods for mechanical devices is underway.

  For example, in Patent Document 1, in the maximum steady rotational speed range, by performing control that alternately and repeatedly performs acceleration rotation that is accelerated and rotated by an electric motor and inertia rotation that is turned off by inertia by turning off the electric current of the electric motor, A technique is disclosed in which the rotation of the mechanical device is kept in the maximum steady rotation speed range, and at this time, the motor is turned off and the motor is turned off at the time of inertia rotation to turn off the electric power to reduce power consumption.

JP 2001-120880 A

  However, the above conventional technique cannot be applied to a mechanical device using an induction motor that rotates at a rated speed. Further, when a high efficiency induction motor is applied to a mechanical device, the rotational speed of the high efficiency induction motor tends to be faster than a conventional induction motor (non-high efficiency induction motor) at the same output. Therefore, as the rotational speed of the induction motor increases, the mechanical output of the pump device itself also increases, and there is a problem that power consumption cannot be reduced sufficiently due to the increase in output.

  This invention is made | formed in view of the above, Comprising: It aims at obtaining the mechanical apparatus to which the highly efficient induction motor which can fully reduce power consumption is applied.

  In order to solve the above-described problems and achieve the object, the present invention provides a mechanical device having an induction motor and a reduction gear, wherein the rotational speed of the mechanical device itself is changed from a non-high efficiency induction motor to a high efficiency induction motor. The reduction gear ratio of the reduction gear is increased so as to be the same as when the non-high-efficiency induction motor before the change is used, and the reduction gear ratio is set to 1.0% or more and 6.0% or less according to the increase in the rotational speed. A mechanical device characterized by an increase.

  According to the present invention, it is possible to obtain a mechanical device to which a high-efficiency induction motor capable of sufficiently reducing power consumption can be obtained.

FIG. 1 is a perspective view illustrating an appearance of a mechanical device according to an embodiment. FIG. 2 is an enlarged cross-sectional view of a belt and a pulley in the mechanical device according to the embodiment. FIG. 3 is a diagram illustrating a loss comparison between a general conventional induction motor (standard motor) and a high-efficiency induction motor (high-efficiency motor) in the mechanical device according to the embodiment. FIG. 4 is a diagram illustrating a relationship between the rotation speed and torque of the induction motor of the mechanical device according to the embodiment. FIG. 5 is a diagram (a partially enlarged view of FIG. 4) illustrating the relationship between the rotational speed and torque of the induction motor of the mechanical device according to the embodiment. FIG. 6 is a diagram illustrating a case where a conventional induction motor and a high efficiency induction motor are used when the secondary resistance ratio of the high efficiency induction motor and the slip s are used as parameters in the mechanical device according to the embodiment. It is a figure which shows the reduction ratio increase rate for making the rotational speed of this equal. FIG. 7 is a cross-sectional view of the gear according to the embodiment.

  Embodiments of a mechanical device according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment.
FIG. 1 is a perspective view showing an appearance of an embodiment of a mechanical device according to the present invention. The mechanical device shown in FIG. 1 is a pump device having an induction motor (motor) and a speed reduction mechanism, and includes an induction motor 21, a pump 22, a belt 23, and pulleys (a small-diameter pulley 31 on the induction motor 21 side and a pump 22 side. Large-diameter pulley 32). The induction motor 21 of the mechanical device shown in FIG. 1 is a high efficiency induction motor. Here, the high-efficiency induction motor refers to an induction motor having a high efficiency and a high rotation speed at the same output as compared with a conventional non-high-efficiency induction motor.

FIG. 2 is an enlarged cross-sectional view of a belt and a pulley in the mechanical apparatus of FIG. In the belt / pulley shown in FIG. 2, the diameter of the large-diameter pulley 32 relative to the diameter of the small-diameter pulley 31 is larger than that of the prior art. For example, if the ratio of the diameter of the conventional small diameter pulley to the diameter of the large diameter pulley is 30:40, the ratio of the diameter of the small diameter pulley and the diameter of the large diameter pulley of this embodiment is 30:41. As described above, when the diameter of the large pulley is increased with respect to the diameter of the small pulley, the reduction ratio when using the high efficiency induction motor can be increased. In this example, the reduction ratio is conventionally 40/30. Becomes a reduction ratio of 41/30. Specifically, the rotational speed of the induction motor 21 and _{N m,} the ratio of the diameter _{D L} of the diameter _{D S} and the large diameter pulley 32 of the small diameter pulley 31 _D S: When _{D L,} the rotational speed _{N p} of the pump with reduction ratio _{a = D} L / D _S represented by the following formula (1).

According to the above equation (1), the ratio of the diameter D _L of the diameter D _S and the large diameter pulley 32 of the small diameter pulley 31 as in the above example, when changing from a conventional induction motor with high efficiency induction motor, changing from 30:40 to 30:41, where was speed in _{N m1 N p1} = 0.75N _m1 conventional induction motor when using the pump rotational speed _{N p1} a conventional induction motor, a high efficiency induction in the rotation speed _{N m @ 2} between the rotational speed _{N p2} of the pump when the motor using a high efficiency induction motor becomes _N p2 = 0.73N _m2. On the other hand, the rotation speed N _m2 of the high-efficiency induction motor is faster than the rotation speed N _m1 of the conventional induction motor at the same output (N _m1 <N _m2 is satisfied). As in the present embodiment, when the reduction ratio when using a high-efficiency induction motor is made larger than the reduction ratio when using a conventional induction motor, the rotational speed _Np1 of the pump when using a conventional induction motor and high-efficiency induction are increased. The rotational speed _Np2 of the pump when using the electric motor is approximately equal. Thereby, since the machine output does not change before and after the change of the induction motor, power consumption due to high efficiency of the induction motor 21 can be reduced.

  Next, the rotational speed of the high efficiency induction motor will be described. FIG. 3 is a diagram showing a loss comparison between a general conventional induction motor (standard motor) and a high-efficiency induction motor (high-efficiency motor). The loss shown in FIG. 3 is composed of primary copper loss, secondary copper loss, iron loss, stray load loss and mechanical loss. According to FIG. 3, the primary copper loss and the secondary copper loss are reduced in the high-efficiency induction motor as compared with a general conventional induction motor. This is because in a high-efficiency induction motor, primary resistance and secondary resistance are reduced in order to increase the efficiency of the induction motor, that is, to reduce loss.

  Further, the resistance and rotation speed of the induction motor will be described. The motor output of the induction motor can be expressed by the following equation (2).

Where _PM is the motor output, V is the power supply voltage, s is the slip, r ₁ is the primary resistance, r ₂ is the secondary resistance, x ₁ is the primary reactance, x ₂ is the secondary reactance. In general, since the induction motor has s << 1 during rated operation, the relationship between slip and output can be approximated by the following equation (3) from the above equation (2).

  From the above equation (3), the slip s when the output is constant is expressed by the following equation (4).

  From the above equation (4), the rotational speed N of the induction motor when the output is constant is expressed by the following equation (5).

Here, N ₀ is the synchronous speed, f _e is the power _{frequency, p} is a number of pole pairs of the induction motor. From the above equation (4), when the secondary resistance is reduced, the slip at the rated output of the induction motor is also reduced, and from the above equation (5), the rotational speed is increased.

  FIG. 4 is a diagram showing the relationship between the rotational speed and torque of the induction motor. FIG. 5 shows the relationship between the rotational speed and torque of the induction motor, and is an enlarged view of FIG. 4 and 5, a curve 41 is a curve of a conventional induction motor, a curve 42 is a curve of a high-efficiency induction motor, and a curve 43 is a curve when a reduction ratio change is performed on the high-efficiency induction motor. . 4 and 5 also show the relationship between the rotational speed and load torque (curve 44) in a general application. The operating point is the intersection of the load torque (curve 44) and the speed torque (curves 41, 42, 43) of the induction motor.

  In FIG. 5, from the load torque in a general application, the operating point of the conventional induction motor is point L (intersection of curve 41 and curve 44), and the operating point of the high efficiency induction motor is point M (curve 42 and (Intersection of curve 44). This is because in the high efficiency induction motor, the secondary resistance is reduced, so that the slip at the rated output of the induction motor is also reduced and the rotational speed is increased. In this way, both the speed and the torque are greater at point M than at point L, resulting in increased output. And according to it, input electric power will also increase and although it is highly efficient as an induction motor, there is a possibility that it may increase as the power consumption of a mechanical apparatus.

  On the other hand, FIG. 4 and FIG. 5 also show characteristics (curve 43) when the reduction ratio when using a high-efficiency induction motor is larger than when using a conventional induction motor. 4 and 5, the speed reduction ratio when using a high-efficiency induction motor is increased compared to the case where a conventional induction motor is used, so that the rotational speed and high efficiency of a mechanical device when using a conventional induction motor are increased. When the induction motor is used, the rotation speed of the mechanical device is substantially equal at the point L, and the machine output does not change before and after the induction motor is changed. Thus, according to the present embodiment, the increase in input power due to the increase in the output of the mechanical device is eliminated, and the power consumption reduction effect due to the high efficiency of the induction motor can be brought out.

The reduction ratio may be determined by paying attention to the fact that the rotational speed of the induction motor changes depending on the secondary resistance. The reduction ratio when using the conventional induction motor is α, the reduction ratio when using the high efficiency induction motor is β, the secondary resistance of the conventional induction motor is r ₂ , and the secondary resistance of the high efficiency induction motor is A · r ₂ ( When a is the ratio of the secondary resistance) of a conventional induction motor and high efficiency induction motor, the conditions for the rotational speed N _p and the same machine, the above formula (5) or the like, and N _{p =} N ₁ It is expressed by the following formula (6) from / α = N ₂ / β.

  Therefore, the reduction ratio β for equalizing the rotation speed when using the conventional induction motor and when using the high efficiency induction motor is expressed by the following equation (7).

  Therefore, when the reduction ratio β is determined by the above equation (7), the rotational speed when using the conventional induction motor and the rotational speed when using the high-efficiency induction motor are substantially equal, and the machine output changes before and after the induction motor is changed. Therefore, it is possible to maximize the power consumption reduction effect by increasing the efficiency of the induction motor.

  Further, the reduction ratio increase rate is determined by paying attention to the above equation (6). FIG. 6 is a diagram for equalizing the rotation speed when using the conventional induction motor and when using the high efficiency induction motor when the secondary resistance ratio and the slip s of the high efficiency induction motor with respect to the conventional induction motor are used as parameters. It is a figure which shows the reduction ratio increase rate. In FIG. 6, a straight line 51 is a straight line indicating a reduction ratio increase rate when the standard motor slip is 6%, and a straight line 52 is a straight line indicating a reduction ratio increase rate when the standard motor slip is 5%. Is a straight line showing the reduction ratio increase rate when the standard motor slip is 4%, the straight line 54 is a straight line showing the reduction ratio increase rate when the standard motor slip is 3%, and the straight line 55 is the standard motor slip 2 It is the straight line which shows the reduction ratio increase rate when it is%. As shown in FIG. 6, the lower the secondary resistance ratio of the high-efficiency induction motor to the conventional induction motor and the larger the slip (rated rotational speed) of the conventional induction motor, the more the rotation speed before and after the induction motor change becomes equal. Increase rate of reduction ratio increases. Specifically, assuming that the secondary resistance of the high-efficiency induction motor is approximately 50% or less of the conventional induction motor, the reduction ratio needs to be 1.01 to 1.06 times.

  In the present embodiment, the ratio A of the secondary resistance between the conventional induction motor and the high-efficiency induction motor used in the above equation (6) is calculated by a restraint test of the induction motor, and the reduction ratio β is calculated as described above. It calculates by Formula (7). The induction motor restraint test means that a low voltage of the rated frequency is applied to the primary winding of the induction motor while the rotor of the induction motor is fixed, and a restraining current close to the rated current is applied to the primary winding. This is a test to calculate the secondary resistance by measuring the primary side input. In the restraint test, it is possible to more accurately determine the reduction ratio at which the rotation speed is the same before and after the induction motor is changed, and it is possible to maximize the power consumption reduction effect by increasing the efficiency of the induction motor. .

In the present embodiment, the reduction ratio β when using a high-efficiency induction motor is N ₁ as the rated rotational speed of the conventional induction motor, and α is the reduction ratio when using the conventional induction motor. Assuming that the rated rotational speed of N ₂ is N ₂ , it is expressed by the following equation (8).

  Since induction motors are mostly used near the rated rotation speed, the rotation speed before and after the induction motor change is often the same by determining the reduction ratio using the above equation (8). Become. As a result, it is possible to maximize the power consumption reduction effect by increasing the efficiency of the induction motor.

  In this embodiment, the pulley diameter is changed in order to change the reduction ratio. However, the present invention is not limited to this, and the number of gear teeth is changed in a mechanical device having a reduction gear as a gear structure. It may be a structure to do (FIG. 7). FIG. 7 is a diagram showing a form in which the present invention is applied to a gear. In FIG. 7, the gear 61 corresponds to a small diameter pulley, and the gear 62 corresponds to a large diameter pulley. As described in the present embodiment, the gear changing method may be such that the rotational speeds when using a conventional induction motor and when using a high-efficiency induction motor are equal. As a result, there is no change in the rotational speed before and after the induction motor is changed, so that it is possible to maximize the power consumption reduction effect by increasing the efficiency of the induction motor.

  As described above, the mechanical device according to the present embodiment includes an induction motor that rotates a small-diameter pulley (or small-diameter gear) and a large-diameter pulley (or large-diameter gear) that is driven by the rotational motion of the small-diameter pulley. An apparatus including a connected rotating mechanism, wherein an increase in rotational speed due to the induction motor being a high-efficiency induction motor is greater than the diameter of the small-diameter pulley (or small-diameter gear). The reduction ratio, which is the ratio of the diameters of the diameter pulleys (or large gears), is offset by the large diameter pulleys (or large diameter gears), and the induction motor is rotated by using a high-efficiency induction motor. The increase in the rotation speed of the large-diameter pulley (or large-diameter gear) due to the increase in speed is suppressed. Alternatively, in the mechanical device according to the present embodiment, in a mechanical device having an induction motor and a reduction gear, the rotational speed of the mechanical device itself changed from a non-high efficiency induction motor to a high efficiency induction motor is a non-high speed before the change. The reduction gear ratio of the reduction gear is increased so as to be equivalent to that when an efficiency induction motor is used. By adopting such a configuration, it is possible to maximize the power consumption reduction effect due to the high efficiency of the induction motor.

  In the mechanical device configured as described above, the reduction ratio may be determined based on a secondary resistance of the induction motor. Such a form is shown by said Formula (7), for example. By adopting such a configuration, the rotational speed does not change before and after the induction motor is changed, so that the power consumption reduction effect due to the high efficiency of the induction motor can be maximized.

  Moreover, what is necessary is just to calculate the said secondary resistance of the said induction motor by a restraint test in the mechanical apparatus of the said structure. With such a configuration, since the reduction ratio is accurately determined and the rotation speed does not change before and after the induction motor is changed, the power consumption reduction effect due to the high efficiency of the induction motor can be maximized.

  In the mechanical device having the above-described configuration, the reduction ratio of the induction motor may be determined based on a ratio of a rated rotation speed of the induction motor. Such a form is shown by said Formula (8), for example. By adopting such a configuration, since the rotation speed does not change before and after the induction motor is changed, the power consumption reduction effect due to the high efficiency of the induction motor can be maximized.

  In the mechanical device having the above configuration, the reduction ratio, which is the ratio of the diameter of the large-diameter pulley to the diameter of the small-diameter pulley, is 1 according to the increase in rotational speed due to the induction motor being a high efficiency induction motor. It may be determined between 0.0% and 6.0%. By adopting such a configuration, it is possible to maximize the energy saving effect due to higher motor efficiency.

  Alternatively, in a mechanical device similar to the above-described configuration, the increase in rotational speed due to the induction motor being a high-efficiency induction motor increases the reduction ratio, which is the ratio of the diameter of the large pulley to the diameter of the small pulley. Instead, it may be offset in the large-diameter pulley by reducing the frequency of the power source that supplies power to the induction motor. In other words, when replacing a conventional induction motor that uses a variable frequency power source such as an inverter with a high-efficiency induction motor in a mechanical device having an induction motor and a speed reduction mechanism, the rotational speed of the mechanical device is equivalent to that when using a conventional induction motor. It is better to reduce the output frequency of the inverter so that The output frequency of the inverter is reduced so that the rotational speed of the mechanical device is equivalent to that when using a conventional induction motor. Specifically, the output frequency of the inverter is 1 / β or Reduce by about 1.0-6.0%. As a result, the rotational speed does not change before and after the induction motor is changed, and the power consumption reduction effect due to the high efficiency of the induction motor can be maximized.

  As described above, the mechanical device according to the present invention is useful for equipment including an induction motor.

  21 induction motor, 22 pump, 23 belt, 31 small-diameter pulley, 32 large-diameter pulley, 41-44 curve, 51-55 straight line, 61, 62 gear (gear).

Claims (6)

An induction motor that rotates a small pulley,
A device including a rotation mechanism connected to a large-diameter pulley driven by the rotational movement of the small-diameter pulley,
The increase in rotational speed due to the induction motor being a high-efficiency induction motor is offset in the large-diameter pulley by increasing the reduction ratio, which is the ratio of the diameter of the large-diameter pulley to the diameter of the small-diameter pulley. And
An increase in rotational speed of the large-diameter pulley due to an increase in rotational speed due to the induction motor being a high-efficiency induction motor is suppressed,
The reduction gear ratio is increased by 1.0% or more and 6.0% or less in accordance with an increase in rotational speed by using the induction motor as a high-efficiency induction motor. An induction motor that rotates a small-diameter gear;
A device including a rotation mechanism connected to a large-diameter gear driven by the rotational movement of the small-diameter gear,
The increase in rotational speed due to the induction motor being a high-efficiency induction motor is offset in the large-diameter gear by increasing the reduction ratio, which is the ratio of the diameter of the large-diameter gear to the diameter of the small-diameter gear. And
An increase in the rotation speed of the large-diameter gear due to an increase in rotation speed due to the induction motor being a high-efficiency induction motor is suppressed,
The reduction gear ratio is increased by 1.0% or more and 6.0% or less in accordance with an increase in rotational speed by using the induction motor as a high-efficiency induction motor. An induction motor that rotates a small pulley,
A device including a rotation mechanism connected to a large-diameter pulley driven by the rotational movement of the small-diameter pulley,
The increase in rotational speed due to the induction motor being a high-efficiency induction motor is offset in the large-diameter pulley by reducing the frequency of the power source that supplies power to the induction motor,
An increase in rotational speed of the large-diameter pulley due to an increase in rotational speed due to the induction motor being a high-efficiency induction motor is suppressed,
A mechanical device characterized in that the frequency of the power source is reduced by 1.0% or more and 6.0% or less in accordance with an increase in rotational speed. An induction motor that rotates a small-diameter gear;
A device including a rotation mechanism connected to a large-diameter gear driven by the rotational movement of the small-diameter gear,
The increase in rotational speed due to the induction motor being a high-efficiency induction motor is offset in the large-diameter gear by reducing the frequency of the power source that supplies power to the induction motor,
An increase in the rotation speed of the large-diameter gear due to an increase in rotation speed due to the induction motor being a high-efficiency induction motor is suppressed,
A mechanical device characterized in that the frequency of the power source is reduced by 1.0% or more and 6.0% or less in accordance with an increase in rotational speed. In a mechanical device having an induction motor and a reduction gear,
Increase the reduction ratio of the reduction gear so that the rotational speed of the mechanical device itself changed from the non-high efficiency induction motor to the high efficiency induction motor is equivalent to that when using the non-high efficiency induction motor before the change, A machine apparatus characterized in that the ratio is increased by 1.0% or more and 6.0% or less in accordance with an increase in rotational speed. In a mechanical device having an induction motor and a reduction gear,
The frequency of the power source that supplies power to the induction motor is set so that the rotation speed of the mechanical device itself changed from the non-high efficiency induction motor to the high efficiency induction motor is equivalent to that when using the non-high efficiency induction motor before the change. Make it smaller
A mechanical device characterized in that the frequency of the power source is reduced by 1.0% or more and 6.0% or less in accordance with an increase in rotational speed.

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