Brushless motor pump

Abstract

A brushless motor pump includes a case; a motor disposed in the case, and including a rotor and a stator; a rotary blade assembly connected to one end of the rotor; a blade housing mounted to the case and encompassing the rotary blade assembly; an excitation unit for energizing the stator; and a control unit for generating an operating frequency which increases gradually from an initial low value to a constant high value so that the rotor starts to operate at a low speed and continues its operation to a high constant speed.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority of Taiwanese Application No. 094100632, filed on Jan. 10, 2005.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a pump, and more particularly to a brushless motor pump.

2. Description of the Related Art

Referring to FIGS. 1 and 2, a conventional single-phase brushless motor pump 1 includes a motor 10, a hollow case 11, a fan blade member 14, and a front cover 15.

The hollow case 11 includes a main housing 112 that defines a chamber 111 and has a front face 114. The case 11 further includes a circular boss 115 that projects from the front face 114 of the main housing 112, a cylinder 116 extended into the chamber 111 from the circular boss 115, an opening 117 formed in the circular boss 115 at a location corresponding to the cylinder 116, and a pair of L-shaped connectors 118 formed symmetrically about the circular boss 115.

The motor 10 includes a coil 12 and a rotor 13. The rotor 13 includes a rotating shaft 131, and an annular magnetic member 132 surrounding an outer circumference of the rotating shaft 131. The fan blade member 14 is mounted on a front end of the rotating shaft 131 of the rotor 13, and the rotor 13 is inserted into the cylinder 116 through the opening 117 such that the fan blade member 14 is positioned outside the opening 117. The coil 12 is mounted in the chamber 111 surrounding the cylinder 116. Silicon steel laminations 121 of the coil 12 oppose the magnetic member 132 of the rotor 13 so that the coil 12 is subjected to the magnetic attraction force of the magnetic member 132. The front cover 15 includes a front wall 151, a circumferential wall 152 extending from an outer circumference of the front wall 151 to thereby define a hollow 150, and a pair of flanges 154 extending from a distal end of the circumferential wall 152. Gaps 153 are formed between the pair of the flanges 154. A hollow intake tube 156 is formed protruding from the front wall 151 such that a center axis of the intake tube 156 substantially corresponds to an axis of rotation of the fan blade member 14, and a hollow exhaust tube 157 is formed protruding from the circumferential wall 152.

The front cover 15 is secured to the hollow case 11 by first aligning the gaps 153 of the front cover 15 to the connectors 118 of the hollow case 11, then rotating the front cover 15 by approximately a half turn.

Referring to FIG. 3A, the conventional synchronous motor pump further includes an excitation circuit 16. When external power is supplied to the excitation circuit 16, the coil 12 is operated to generate a magnetic flux effect to thereby induce the rotor 13 to rotate. Through such operation of the motor 10, water enters through the intake tube 156, then is exhausted via the exhaust tube 157 by the rotation of the fan blade member 14 fixed to the rotating rotor 13. Hence, pumping of a liquid substance such as water is realized.

Although the conventional pump can achieve its intended purpose, it nevertheless suffers from many drawbacks as follows:

1. With reference to FIG. 4, there is a lag between when power is first provided to the motor pump 1 and when the rotor 13 reaches its desired final rotational speed. Since full power is supplied to the motor 10 at this initial stage prior to when the rotor 13 reaches its final speed, there is a loss of energy.

2. Referring to FIG. 3B, since the conventional single-phase synchronous motor pump does not have a starting coil, there is a minimal starting torque and the rotational direction is not fixed. Therefore, the rotor 13 must be rotatably interconnected with the fan blade member 14 (i.e., rotatable over a fixed range). When the rotating shaft 131 of the rotor 13 starts to operate, it rotates up to 270 degrees to cause a protuberance 1311 of the rotating shaft 131 to collide against a blocking member 141 of the fan blade member 14. If the rotation of 270 degrees does not actuate the fan blade member 14, the direction of the rotor 13 will reverse so that the rotating shaft 131 moves in the opposite direction by 270 degrees to collide with an opposite side of the blocking member 141 to drive the fan blade member 14. However, since the fast starting resistance of the conventional pump is large, when the rotor 13 is instantly rotated one direction then in the reverse direction, the high-speed collision between the protuberance 1311 and the blocking member 141 results in easy damage to the fan blade member 14, the protuberance 1311, and the blocking member 141.

SUMMARY OF THE INVENTION

Therefore, the object of the present invention is to provide a brushless motor pump that minimizes use of power, and that can operate and discharge water smoothly.

According to the present invention, a brushless motor pump comprises: a case; a motor disposed in the case, and including a rotor and a stator; a rotary blade assembly connected to one end of the rotor; a blade housing mounted to the case and encompassing the rotary blade assembly; an excitation unit for energizing the stator; and a control unit for generating an operating frequency which increases gradually from an initial low value to a constant high value so that the rotor starts to operate at a low speed and continues its operation to a high constant speed.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, of which:

FIG. 1 is a partly exploded perspective view of a conventional brushless motor pump;

FIG. 2 is a sectional view of the conventional brushless motor pump, illustrating the flow of water in the brushless motor pump;

FIG. 3A is a schematic circuit block diagram of an excitation circuit and a motor of the conventional brushless motor pump;

FIG. 3B is a partly sectioned view illustrating a rotor and a fan blade assembly of the conventional brushless motor pump;

FIG. 4 is a timing diagram of a signal used to drive the motor of the conventional brushless motor pump;

FIG. 5 is a partly exploded perspective view of a brushless motor pump according to a first preferred embodiment of the present invention;

FIG. 6 is a sectional view of the first preferred embodiment, illustrating the flow of water in the brushless motor pump;

FIG. 7 is a schematic circuit block diagram of a control unit and a motor of the first preferred embodiment;

FIG. 8 is a timing diagram of a signal used to drive a motor of the first preferred embodiment;

FIG. 9 is a partly exploded perspective view of a modified example,of the brushless motor pump of the first preferred embodiment;

FIG. 10 is a partly exploded perspective view of a brushless motor pump according to a second preferred embodiment of the present invention;

FIG. 11 is a schematic circuit block diagram of a control unit, a motor, and a magnetism detector of the second preferred embodiment;

FIG. 12 is a circuit diagram of the control unit of the second preferred embodiment;

FIG. 13 is a partly sectioned view illustrating a rotor and a rotary blade assembly of the preferred embodiments when having a fixed connection; and

FIG. 14 is a partly sectioned view illustrating the rotor and the rotary blade assembly of the preferred embodiments when having a pivotable connection.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Before the present invention is described in greater detail, it should be noted that like elements are denoted by the same reference numerals throughout the disclosure.

Referring to FIGS. 5 and 6, a brushless motor pump according to a first preferred embodiment of the present invention includes a case 2, a motor 3, a rotary blade assembly 4, a control unit 5, and a blade housing 6. The brushless motor pump may be a single-phase brushless motor pump.

The case 2 includes a main housing 22 that defines a chamber 21 therein. The main housing 22 has a rear end that is open, and a front end that is closed to form a front face 24. The case 2 also includes a rear cover 23 sealing the open rear end of the main housing 22. A circular boss 25 projects from the front face 24 of the main housing 22, and an opening is formed in the circular boss 25. A cylinder 26 is extended into the chamber 21 from the circular boss 25 starting from the opening 27. A pair of connectors 28 of L-shaped cross-section is formed symmetrically about the circular boss 25.

The motor 3 includes a coil unit 30 and a rotor 33. The rotor 33 includes a rotating shaft 331, and an annular magnetic member 332 surrounding an outer circumference of the rotating shaft 331. The rotary blade assembly 4 is rotatably mounted on a front end of the rotating shaft 331 of the rotor 33 in substantially a coaxial position with the rotating shaft 331, and the rotor 33 is inserted into the cylinder 26 through the opening 27 such that the rotary blade assembly 4 is positioned outside the opening 27. The coil unit 30 is mounted in the chamber 21. The coil unit 30 includes a plurality of silicon steel laminations 310 that form a core 31 of a substantially U-shaped cross-section, and a plurality of coils 32 provided partly surrounding the core 31. The coil unit 30 is positioned over the outer circumference of the cylinder 26 such that the core 31 opposes the magnetic member 332 of the rotor 33. The coil unit 30 is subjected to the magnetic attraction force of the magnetic member 332.

The blade housing 6 includes a front wall 61, a circumferential wall 62 extending from an outer circumference of the front wall 61 to thereby form a hollow 610, and a pair of flanges 64 extending from an outer circumference of the circumferential wall 62 at a distal end portion thereof. Gaps 63 are formed between the pair of the flanges 64. A hollow intake tube 65 is formed on the front wall 61 that extends away from the same. A center axis of the intake tube 65 substantially corresponds to an axis of rotation of the rotary blade assembly 4. A hollow exhaust tube 66 is formed on the circumferential wall 62 and extends away from the same. The blade housing 6 is mounted to the case 2 in a conventional manner and such that the blade housing 6 encompasses the rotary blade assembly 4.

The control unit 5 is mounted in the case 2 as shown in FIG. 6. Referring to FIGS. 7 and 8, the control unit 5 includes a signal control unit 51 and an excitation unit 52. The excitation unit 52 energizes the coil unit 30. That is, the excitation unit 52 is connected to an input terminal 301 of the coil unit 30, and effects a magnetic excitation of the coil unit 30 so that the rotor 33 rotates. The signal control unit 51 supplies power to the excitation unit 52, and is able to generate signals of differing frequencies which increase gradually from an initial low frequency level to a high frequency level. In the preferred embodiment, the signal control unit 51 generates a continuous train of pulse signals of increasing frequencies as shown in FIG. 8. When the signal control unit 51 starts its operation, it provides a pulse signal of a low frequency. Hence, at the beginning of operation, the coil unit 30 is operated such that the rotor 33 rotates slowly. The signal control unit 51 gradually increases the frequency of the pulse signal until it reaches a predetermined level, at which point the pulse signal is maintained at a constant level. In this state, the rotor 33 rotates at a higher speed.

Referring to FIGS. 10, 11, and 12, a second preferred embodiment of the present invention includes a case 2, a motor 3, a rotary blade assembly 4, a control unit 5, and a blade housing 6. Except for the control unit 5, all other aspects of the second preferred embodiment are identical to the first preferred embodiment. Therefore, only the control unit 5 will be described in the following.

The control unit 5 of the second preferred embodiment further includes a magnetism detector 53. As an example, the magnetism detector 53 may be a Hall sensor. The magnetism detector 53 is electrically connected to both the signal control unit 51 and the motor 3. The magnetism detector 53 produces signals indicative of angular positions of N and S poles of the rotor 33, then transmits the signals to the signal control unit 51. The supply of the signals is uninterrupted, and the signal control unit 51 uses these signals to optimize driving of the rotor 33 so that the rotor 33 rotates more smoothly.

Referring again to FIG. 6, in the first and second preferred embodiments, the core 31 functions as the stator of the motor 3, and are therefore positioned surrounding the rotor 33. When the coil unit 30 is supplied power, the core 31 creates a magnetic field. However, the single phase coil laminations produce parallel attraction and repulsion forces without rotational forces.

The core 31 has the U-shaped cross section as described above and includes a bottom segment 3110, and a pair of opposing side arms 3111 that extend upwardly from the bottom segment 3110. The bottom segments 3110 of the core 31 cooperate with inner walls 3112 of the side arms 3111 thereof to define a channel 311 to receive the rotor 33. The inner walls 3112 of the core 31 respectively have recessed surfaces 312 that confront the rotor 33. Each of the recessed surfaces 312 includes a shallow region 3121 and a deep region 3122. A distance D between the shallow region 3121 and the rotor 33 is smaller than a distance D1 between the deep region 3122 and the rotor 33. The shallow regions 3121 of the recessed surfaces 312 are arranged substantially at two diametrically opposed positions relative to the rotor 33. Similarly, the deep regions 3122 of the recessed surfaces 312 are arranged substantially at two diametrically opposed positions relative to the rotor 33.

As a result of the difference in the distances D1, D, magnetic flux densities of differing intensities are created around the rotor 33, thereby resulting in different magnetic forces. This, in turn, causes the N and S poles of the rotor 33 to alternate. Hence, the force needed for the initial rotation of the rotor 33 is formed.

With reference to FIG. 9, in a modified example, the depth of recessed surfaces 312′ of the core 31 is gradually increased so that there is a smooth transition between shallow regions 3121′ and deep regions 3122′. As with the configuration described with reference to FIG. 6, the distance D1 between each deep region 3122′ and the rotor 33 is greater than the distance D between each shallow region 3121′ and the rotor 33. Also, the pair of the shallow regions 3121′ and the pair of the deep regions 3122′ are formed at diametrically opposed positions relative to the rotor 33 such that the distances D1, D are positioned opposite to one another. A magnetism detector 53 may be included in the configuration of the modified example as in the second preferred embodiment described above.

Referring back to FIGS. 11 and 12, the excitation unit 52 includes a number of power transistors 521 (Q6 and Q7), and is connected to the input terminal 301 of the coil unit 30. When the excitation unit 52 receives power, it performs an excitation function by causing the coil unit 30 to undergo quick conversion between positive and negative poles to thereby drive the rotor 33 by the rapid conversion between N and S poles of the coil unit 30. Hence, rapid driving is achieved.

The brushless motor pump of the present invention described above has advantages over the conventional configuration as follows:

1. Power saving: Since the signal control unit 51 supplies power of differing frequencies to the excitation unit 52, the rotor 33 is rotated starting from a slow speed and increasing to a fast speed. When the motor 3 is initially started, it does not produce any output, and, therefore, requires a relatively small supply of power. Power consumption may be reduced by supplying a small initial power that gradually increases.

2. Smooth driving: With the addition of the magnetism detector 53 in the second preferred embodiment, and with the different depths between the shallow regions 3121 and the deep regions 3122 of the silicon steel laminations 31, the magnetism detector 53 is able to sense changes in the north and south poles of the rotor 33, and transmit corresponding signals to the signal control unit 51. The supply of the signals is uninterrupted, and the rotor 33 that is excited to undergo rotation does so more smoothly by the use of this data by the signal control unit 51.

With reference to FIG. 13, since the rotor 33 of the present invention is driven from a slow speed to a fast speed, the resistance against rotation is small during initial operation. Therefore, the rotary blade assembly 4 of the present invention may be fixedly connected to the rotating shaft 331 of the rotor 33. When the rotor 33 starts to rotate, it can easily make the rotary blade assembly 4 achieve the necessary rotational speed.

Referring to FIG. 14, the rotary blade assembly 4 may also have a pivotable structure. In this case, the rotary blade assembly 4 includes a blocking member 41 that extends over a range of approximately 90 degrees, and the rotating shaft 331 of the rotor 33 includes a protuberance 3311. When the rotor 33 rotates, after rotating 270 degrees, the protuberance 3311 collides against an opposite side 411 of the blocking member 41 of the rotary blade assembly 4 opposite an initial side 410 where the protuberance 3211 is initially positioned. The rotor 33 then rotates in the opposite direction, and again drives the rotary blade assembly 4 until reaching the desired speed. Since the rotor 33 is initially driven at a slow speed, the prior art drawbacks of damage to the rotary blade assembly 4 and/or the protuberance 3311 are not encountered in the present invention.

In addition, in the coil unit 30 of the present invention, the coils 32 cover the U-shaped silicon steel laminations 310. As a result, the structure is simple, and is therefore suitable for automated manufacture. In addition, the number of power elements of the present invention (i.e., the power transistors 521) is smaller than that used in two-phase or three-phase winding coils. Manufacturing costs are reduced since fewer parts are needed.

While the present invention has been described in connection with what is considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.

Claims

1. A brushless motor pump, comprising:

a case;

a motor disposed in said case, and including a rotor and a coil unit;

a rotary blade assembly connected to one end of said rotor;

a blade housing mounted to said case and encompassing said rotary blade assembly;

an excitation unit for energizing said coil unit; and

a control unit for generating signals of differing frequencies which increase gradually from an initial low frequency level to a high frequency level so that said rotor starts to operate at a low speed and continues its operation to a high constant speed.

2. The brushless motor pump of claim 1, further comprising a magnetism detector connected to said control unit for producing signals indicative of angular positions of said rotor.

3. The brushless motor pump of claim 1, wherein said stator includes a core of a substantially U-shaped cross-section, said core including two opposite inner walls confining a channel that receives said rotor, said inner walls having opposite recessed surfaces confronting said rotor, each of said recessed surfaces having a shallow region and a deep region, the distance between said shallow region and said rotor being smaller than that between said deep region and said rotor, said shallow regions of said recessed surfaces being arranged substantially at two diametrically opposed positions relative to said rotor, and said deep regions of said recessed surfaces being arranged substantially at two diametrically opposed positions relative to said rotor.

4. The brushless motor pump of claim 1, wherein said rotary blade assembly is mounted on said rotor substantially in a coaxial position.

5. The brushless motor pump of claim 4, wherein said rotary blade assembly is turnable relative to said rotor by an angle of substantially 270 degrees.