US20200095997A1

US20200095997A1 - Brushless motor integrated pump

Info

Publication number: US20200095997A1
Application number: US16/578,263
Authority: US
Inventors: Teruyuki Wakabayashi
Original assignee: Nikki Co Ltd
Current assignee: Nikki Co Ltd
Priority date: 2018-09-21
Filing date: 2019-09-20
Publication date: 2020-03-26
Also published as: JP2020051256A

Abstract

A brushless motor integrated pump may include a brushless motor having a rotary shaft, a rotor axially mounted on the rotary shaft, a stator disposed around the rotor, a motor case forming a part of a case body and in which the rotor and the stator are accommodated, a motor cover covering the motor case with the rotary shaft penetrating through and protruding from an opening of the motor case, and low and high pressure-side gear pumps sharing the rotary shaft as a driving source and accommodated in a multistage manner inside a pump cover disposed on a surface of the motor cover to form the case body with the motor case. A low-pressure-side outlet may be formed in a pressurizing space communicated with a high-pressure-side outlet formed in the pressurizing space, in which a working medium may be introduced from the low-pressure-side inlet to flow, in order, into the low and high pressure-side gear pumps and may be pressurized, introduced into the motor case via a connection port which may be a high-pressure-side outlet formed in the motor cover, and caused to flow out from a case body outlet formed in the motor case. Low and high pressure outflow paths may be provided in which the low pressure outflow path may be communicated with the low-pressure-side outlet of the low-pressure-side working medium discharged from a pressurizing space of the low-pressure-side gear pump, or the high-pressure-side inlet of the high-pressure-side gear pump, to cause the low-pressure-side working medium to flow out from the low-pressure-side outlet of the low-pressure-side gear pump formed in the pump cover, and the high pressure outflow path may discharge the high-pressure-side working medium from the case body outlet formed in the motor case and discharged from the pressurizing space of the high-pressure-side gear pump. The pump may further have a connection passage including a check valve that may open the low and high pressure-side outflow paths toward the low-pressure-side outflow path.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No. 2018-177937, filed on Sep. 21, 2018, the contents of which are hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a brushless motor integrated pump including a gear pump for pumping a working medium of a waste heat recovery system, such as a Rankine cycle, and a motor for sharing a rotary shaft with the gear pump and applying a driving force to the gear pump. More particularly, the present invention relates to a gear pump including a plurality of rotary pumps.

BACKGROUND

Recently, a brushless motor integrated pump in which a brushless motor shares a rotary shaft with a gear pump to pump a working medium or the like of the waste heat recovery system is provided and achieves high efficiency and high durability, as disclosed in JP 2016-101042 A.
The brushless motor integrated pump includes a rotor which is axially mounted on the rotary shaft of the brushless motor and a stator disposed around the rotor, and the rotor and the stator are accommodated in a motor case constituting a part of a case body. An opening of the motor case is covered by a motor cover and the rotary shaft penetrates through and protrudes from the opening of the motor case. A gear pump that shares the rotary shaft of the brushless motor is installed on the surface of the motor cover and accommodated inside a pump cover that forms a case body with the motor case. A working medium is introduced from an inlet formed in the pump cover via a connection port, which functions as an outlet of the gear pump formed in the motor cover, into the motor case, and then caused to flow out from the outlet formed in the motor cover.
Meanwhile, there have been cases where a desired high-pressure-side working medium cannot be obtained with one rotary pump, or two-system pressure sources of, for example, a low pressure working medium and a high pressure working medium are necessary as in the breaking apparatus, e.g., for anti-slipping. In these cases, two gear pumps sharing one rotary shaft to discharge different working media of low pressure and high pressure and being arranged in the direction of the rotary shaft are disclosed in, for example, JP 2000-161243 A and JP 2014-510864 A.
Therefore, it is conceivable to apply the brushless motor integrated pump to these two-system gear pumps.
However, the multistage gear pumps disclosed in JP 2000-161243 A described above include the two-system gear pumps arranged apart from each other, so that it is necessary to extend the outlets from the two-system low-pressure and high-pressure gear pumps separately to the brushless motor. Therefore, it is extremely difficult to integrating individual gear pumps, which are separated from each other, with one brushless motor. Further, for example, when the low-pressure gear pump is continuously used for the working medium and the high-pressure gear pump is integrated with the motor, the high-pressure-side gear pump should be driven continuously at a predetermined rotation number even when, for example, the working medium from the low-pressure-side gear pump is used, or the motor is not cooled, which is less economical. Indeed, there is a problem that the maximum pressure should be achieved by the high-pressure gear pump.
Meanwhile, in the gear pump disclosed in JP 2014-510864 A, the low-pressure gear pump of the two-system gear pumps has its outlet connected to the inlet of the high pressure pump, so that the brushless motor integrated pump can easily be adapted to the two-system gear pumps. Although a high pressure working medium can be obtained by the two-system gear pumps, a low pressure working medium, if necessary, is obtained by depressurizing the high pressure working medium discharged from the high-pressured outlet, which causes an economic loss.

SUMMARY

The present invention relates to a brushless motor integrated pump that shares a rotary shaft with gear pumps and integrally includes a motor for applying a driving force to the gear pumps. In particular, a brushless motor includes two-system rotary pumps as gear pumps to which the gear pumps are integrated to share the rotary shaft and achieve a brushless motor integrate pump having a small size and excellent cooling ability. Such a brushless motor integrated pump can achieve high efficiency and high durability and can select and use at least one of the low-pressure-side working medium and the high-pressure-side working medium.
In order to solve the above problem, the present invention provides a brushless motor integrated pump including a rotor axially mounted on a rotary shaft of a brushless motor and a stator disposed around the rotor, the rotor and the stator accommodated in a motor case that forms a part of a case body, a motor cover covering the motor case with the rotary shaft penetrating through and protruding from an opening of the motor case, a low-pressure-side gear pump and a high-pressure-side gear pump that share the rotary shaft of the brushless motor as a driving source and are accommodated in a multistage manner inside a pump cover which is disposed on a surface of the motor cover to form the case body with the motor case, and a low-pressure-side outlet of the low-pressure-side gear pump formed in a pressurizing space communicated with a high-pressure-side outlet of the high-pressure-side gear pump formed in the pressurizing space, in which a working medium is introduced from the low-pressure-side inlet provided in the pump cover to flow into the low-pressure-side gear pump and the high-pressure-side gear pump in this order and is pressurized, introduced into the motor case via a connection port which is a high-pressure-side outlet of the high-pressure-side gear pump formed in the motor cover, and caused to flow out from a case body outlet formed in the motor case, the brushless motor integrated pump includes a low pressure outflow path provided for the low-pressure-side working medium and a high pressure outflow path provided for the high-pressure-side working medium, in which the low pressure outflow path is communicated with the low-pressure-side outlet of the low-pressure-side working medium discharged from a pressurizing space of the low-pressure-side gear pump, or the high-pressure-side inlet of the high-pressure-side gear pump, to cause the low-pressure-side working medium to flow out from the low-pressure-side outlet of the low-pressure-side gear pump formed in the pump cover, and the high pressure outflow path discharges the high-pressure-side working medium from the case body outlet formed in the motor case and discharged from the pressurizing space of the high-pressure-side gear pump, and a connection passage including a check valve that opens the low-pressure-side outflow path and the high-pressure-side outflow path toward the low-pressure-side outflow path.
Further, in the embodiment of the present invention, the check valve included in the connection passage is an electromagnetic valve, so that the working medium of a desired pressure can be reliably obtained.
Further, the flow rate of the low-pressure side gear pump is made smaller than the flow rate of the high-pressure side gear pump to obtain the low pressure working medium and the high pressure working medium, respectively, even when the rotary shaft is shared.
According to the embodiment of the present invention, the brushless motor integrated pump includes the motor that shares the rotary shaft with the two-system integrated gear pumps to apply driving force to the gear pumps, achieves high efficiency and high durability, and, in particular, can choose and use at least one of the low-pressure-side working medium and the high-pressure-side working medium.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a vertical sectional view of a brushless motor integrated pump according to a preferred embodiment of the present invention and is also an explanatory view illustrating a flow path of a working medium;

FIGS. 2A and 2B are explanatory views each illustrating an outline of a high-pressure-side gear pump in FIG. 1;

FIG. 3 is a graph illustrating a relationship between the flow rate of a high-pressure-side pump and the flow rate of the low-pressure-side pump, both pumps rotating at the same rotation number, to obtain a systematically required flow rate range of both pumps;

FIG. 4 is a graph illustrating a relationship between the pump rotation number and the flow rate for the high-pressure-side gear pump and the low-pressure-side gear pump obtained from the system required flow rate range, as illustrated in FIG. 3, to set a combination of the flow rate of the high-pressure-side gear pump and the low-pressure-side gear pump; and

FIG. 5 is a graph illustrating a relationship between the rotation number and the flow rate of an ideal flow rate and an actual measured value of the pump of the gear pumps.

DETAILED DESCRIPTION

A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.
FIGS. 1, 2A, and 2B illustrate a brushless motor integrated pump according to a preferred embodiment of the present invention. A working medium 10 is introduced into a case body 1, which includes a pump cover 2, a motor cover 3, and a motor case 4, from a cover body inlet 21 formed in the pump cover 2. The working medium 10 is made to flow to a case body outlet 41 formed in the motor case 4 via a connection port 31 formed in the motor cover 3. A direct current (DC) brushless motor 7 shares a rotary shaft 6 with a two-system gear pumps including a low-pressure-side gear pump 5 a and a high-pressure-side gear pump 5 b, which are accommodated inside the pump cover 2. A straightening member 8 is disposed between the motor cover 3 and the motor case and connected to the connection port 31. A control unit 9 for controlling the rotation number of the brushless motor 7 is disposed outside the case body 1.
The brushless motor 7 includes a stator 71 and a rotor 72, and the rotary shaft 6 supported by a bushing 61. The stator 71 includes a stator core 711 and a coil 712. Space outside the coil 712 wound around a notch portion 713 of the stator core 711 functions as a working medium channel 714 through which the working medium 10 passes.
Further, at least a part of the end face of the stator core 711 is formed not to pass through a gap between the outer peripheral surface of the motor case 1 and a step portion 42, or pass through the gap to allow a smaller flow rate compared to the working medium passage 714.
The rotor 72 includes a substantially cylindrical rotor core 721, which is axially mounted on the rotary shaft 6, and a magnet 722 fitted to the rotor core 721.
It is particularly preferable that the rotor core 721 is provided with a plurality of through holes (not illustrated) axially symmetrically to penetrate through both end surfaces to achieve weight reduction and cost saving.
Further, the brushless motor integrated pump of the present embodiment includes, at the outside of the case body 1 which is configured to be liquid tight, a power supply (not illustrated) for supplying an electric current to the coil 712 of the stator 71 of the brushless motor land the control device 9 for controlling the rotation number of the rotor 72 of the brushless motor 7. Therefore, it is possible to prevent a failure such as breakage of the parts by immersing the parts in the working medium 10 that fills the case body 1.
Meanwhile, the two- system gear pumps 5 a and 5 b, which are accommodated inside the pump cover 2, are conventional inscribe gear pumps, as illustrated in, for example, FIGS. 2A and 2B, that share the rotary shaft 6 protruding on the top surface of the motor cover 3 of the brushless motor 7 and are accommodated in a multistage manner in the axial direction of the shaft. In each gear pump 5 a (5 b), an inner gear 51 a (51 b) axially mounted on the rotary shaft 6 and an outer gear 53 a (53 b) inscribed in an outer bearing 52 a (52 b) disposed around the inner gear 51 a (51 b) are installed in a partially meshing state. Meanwhile, a crescent-shaped crescent seal 54 a (54 b) is disposed between the inner gear 51 a (51 b) and the outer gear 53 a (53 b) for partitioning a high-pressure-side from a low-pressure-side. The working medium 10 is suctioned from a low-pressure-side inlet 55 a and a high-pressure-side inlet 55 b to move to a suction-side space 56 a (56 b), which is formed between the inner gear 51 a (51 b) and the outer gear 53 a (53 b) across the crescent seal 54 a (54 b). The working medium 10 reaches a pressurizing space 57 a (57 b) where the working medium 10 is pressurized and discharged from a low-pressure-side outlet 58 a and a high-pressure-side outlet 58 b.
In particular, in the present embodiment, the low-pressure-side gear pump 5 a and the high-pressure-side gear pump 5 b are formed in a multistage manner in the axial direction, and the low-pressure-side outlet 58 a of the low-pressure-side gear pump 5 a is communicated with the high-pressure-side gear inlet 55 b of the high-pressure-side gear pump 5 b.
Further, the flow rate of the low-pressure-side gear pump 5 a is smaller than the flow rate of the high-pressure-side gear pump 5 b. With respect to this point, in the present embodiment, since the flow rate of the low-pressure gear pump 5 a uses the common rotary shaft 6 with the high-pressure gear pump 5 b, it is difficult to mutually change the rotation number. Alternatively, for example, it is possible to mutually change the diameter of 51 a (51 b) to change the volume of pressurization space.
Since the present embodiment is configured to drive the low-pressure-side gear pump 5 a and the high-pressure-side gear pumps 5 b using the common rotary shaft 6, the pumps come to rotate at the same rotation number, and the flow rate required by the system needs to be set from the discharge amount of each pump 5 a, 5 b.
FIG. 3 illustrates a system required range of the flow rate of the high-pressure-side gear pump 5 b according to the relationship between the flow rate QH of the high-pressure-side gear pump 5 b and the flow rate QL of the low-pressure-side gear pump 5 a. FIG. 4 illustrates, in the system required range of FIG. 3, a sum of the flow rate QH of the high-pressure-side gear pump 5 a and the flow rate QL of the low-pressure-side gear pump (QH+QL), and a relationship between the pump rotation number and the flow rate for the low-pressure-side gear pump 5 a and the high-pressure-side gear pump 5 b. For example, if the flow rate QH of the high-pressure-side gear pump 5 b illustrated in FIG. 3 is “a”, the flow rate of the low-pressure-side pump 5 b is determined from an intersecting point A of the system required flow rate (i.e., a sum (QH+QL) of the flow rate QH of the high-pressure-side gear pump and the flow rate OL of the low-pressure-side gear pump).
As can be seen from the relationship between the pump rotation number and the flow rate in the ideal flow rate and the pump actual value in the gear pump, the actual gear pump includes an internal leakage which needs to be considered in determining the flow rate.
Disclosed in the present embodiment in communication between the low-pressure-side outlet 58 a of the low-pressure-side gear pump 5 a and the high-pressure-side inlet 55 b of the high-pressure-side gear pump 5 b are a low pressure outflow path 11 for causing the low-pressure-side working medium 10 a to flow out from a cover body outlet 22 formed in the pump cover 2, and a high pressure outflow path 12 for causing the high-pressure-side working medium 10 b to flow out from the case body outlet 41 formed in the motor case 4. Further, a connection passage 14 including a check valve 13 that opens toward the low pressure outflow path 11 is provided to communicate the low pressure outflow path 11 with the high pressure outflow path 12.
In the present embodiment that has been configured as illustrated in FIGS. 1, 2A, and 2B, when the brushless motor 7 is activated, the low-pressure-side gear pump 5 a and the high-pressure-side gear pump 5 b, which share the rotary shaft 6, operate in synchronization with each other. Accordingly, the working medium 10 is suctioned inside from the cover body inlet 21 formed in the pump cover 2 by a negative pressure generated at the low-pressure-side inlet 55 a of the low-pressure-side gear pump 5 a. The working medium 10 is then fed to and pressurized in the pressurized space 57 a by meshing of the inner gear 51 a and the outer gear 53 a, and pumped to the low-pressure-side outlet 58 a as the low-pressure-side working medium 10 a.
The low-pressure-side outlet 58 a of the low-pressure-side gear pump 5 a is connected to the high-pressure-side inlet 55 b of the high-pressure-side gear pump 5 b disposed on the brushless motor 7 side. The low-pressure-side working medium 10 a that has been pumped from the low-pressure-side outlet 58 a of the low-pressure-side gear pump 5 a is suctioned inside from the high-pressure-side inlet 55 b of the high-pressure-side gear pump 5 b, and pressurized and pumped to the high-pressure-side outlet 58 b, as in the case of the low-pressure-side gear pump 5 a.
The high-pressure-side outlet 58 b of the high-pressure-side gear pump 5 b is connected to the connection port 31 formed between the motor cover 3 and the motor case 4. The high-pressure-side working medium 10 b discharged from the low-pressure-side outlet 58 b of the low-pressure-side gear pump 5 b adjusts its direction by a straightening member 8 so as to flow from the connection port 31 in the same direction as the rotating direction of the rotor 72. Accordingly, the high-pressure-side working medium 10 b is introduced into the motor case 4 and exchanges heat by cooling the brushless motor 7 through the working medium path 714 (notch 713) and flow out from the case body outlet 41 formed in the motor case 4. This suppresses heat generation of the coil 712 and reduces load from a drag caused by friction at the bearing or a pressure received from the high-pressure-side working medium 10 b, thus improving durability.
In the present embodiment, the low-pressure-side working medium 10 a flowing out from the cover body outlet 22 formed in the pump cover 2 and the high-pressure-side working medium 10 b flowing out from the case body outlet 41 formed in the motor case 4 are fed to the waste heat recovery system (not illustrated) such as the well-known Rankine cycle used in the practice of the conventional art via the low pressure outflow path 11 and the high-pressure-side flow path 12. The present embodiment can be applied to an operating mechanism (not illustrated) that requires a two-system pressure source using the working media at different pressures with one driving source, thus achieving an efficient use of space and a labor-saving operation.
Further, in the present embodiment, the high-pressure-side working medium 10 b from the high pressure outflow path 12 out of the two systems is obtained as a high pressure working medium pressurized by the low-pressure-side gear pump 5 a and the high-pressure-side gear pump 5 b.
Further, in the present embodiment, the two systems including the low pressure outflow path 11 and the high pressure outflow path 12 are connected by the connection passage 14 via the check valve 13, so that the present embodiment can be used as a supply source of the two-system low pressure-side working medium 10 b with one power source. Adjusting the opening of the check valve can change the pressure of the low-pressure-of working medium 10 a and the low-pressure-side pressurizing of the low-pressure-side.

Claims

1. A brushless motor integrated pump comprising:

a brushless motor having a rotary shaft

a rotor axially mounted on the rotary shaft;

a stator disposed around the rotor;

a motor case forming a part of a case body and in which the rotor and the stator are accommodated;

a motor cover covering the motor case with the rotary shaft penetrating through and protruding from an opening of the motor case;

a low-pressure-side gear pump and a high-pressure-side gear pump that share the rotary shaft of the brushless motor as a driving source and are accommodated in a multistage manner inside a pump cover which is disposed on a surface of the motor cover to form the case body with the motor case;

a low-pressure-side outlet of the low-pressure-side gear pump formed in a pressurizing space communicated with a high-pressure-side outlet of the high-pressure-side gear pump formed in the pressurizing space, in which a working medium is introduced from the low-pressure-side inlet provided in the pump cover to flow into the low-pressure-side gear pump and the high-pressure-side gear pump in this order and is pressurized, introduced into the motor case via a connection port which is a high-pressure-side outlet of the high-pressure-side gear pump formed in the motor cover, and caused to flow out from a case body outlet formed in the motor case;

a low pressure outflow path provided for the low-pressure-side working medium and a high pressure outflow path provided for the high-pressure-side working medium, in which the low pressure outflow path is communicated with the low-pressure-side outlet of the low-pressure-side working medium discharged from a pressurizing space of the low-pressure-side gear pump, or the high-pressure-side inlet of the high-pressure-side gear pump, to cause the low-pressure-side working medium to flow out from the low-pressure-side outlet of the low-pressure-side gear pump formed in the pump cover, and the high pressure outflow path discharges the high-pressure-side working medium from the case body outlet formed in the motor case and discharged from the pressurizing space of the high-pressure-side gear pump; and

a connection passage including a check valve that opens the low-pressure-side outflow path and the high-pressure-side outflow path toward the low-pressure-side outflow path.

2. The brushless motor integrated pump according to claim 1, wherein the check valve included in the connection passage is a solenoid valve.

3. The brushless motor integrated pump according to claim 1, wherein a flow rate of the low-pressure-side gear pump is smaller than a flow rate of the high-pressure-side gear pump.

4. The brushless motor integrated pump according to claim 2, wherein a flow rate of the low-pressure-side gear pump is smaller than a flow rate of the high-pressure-side gear pump.