ELECTRIC WORK MACHINE

• US 20170239804A1
• Filed: 09/29/2015
• Published: 08/24/2017
• Est. Priority Date: 10/31/2014
• Status: Active Grant

• Current Assignee: Koki Holdings Co., Ltd.
• Original Assignee: Hitachi KOKI Company Limited (Koki Holdings Co., Ltd.)
• Inventors: MATSUSHITA, Akira, NISHIKAWA, Tomomasa, NOGUCHI, Yuta, KANBE, Kuniaki, YAMAZAKI, Shingo
• Granted Patent: US 11,052,530 B2
• Time in Patent Office: Days
• CPC Class Codes: B25F 5/008 Cooling means
• CPC Class Codes: H02K 11/33 Drive circuits, e.g. power electronics H02K11/38 takes precedence
• CPC Class Codes: H02K 9/06 with fans or impellers driven by the machine shaft
• CPC Class Codes: H02P 6/16 Circuit arrangements for detecting position

Abstract

Provided is an electric work machine that can suppress a temperature increase of a component controlling an electric motor. The electric work machine including a brushless motor that operates a tip tool includes a rectification circuit that converts a voltage to be applied to the brushless motor from an alternating current voltage to a direct current voltage, and a switching circuit that controls the brushless motor, and the rectification circuit is arranged upstream of the switching circuit in a circulation path of the air that cools the rectification circuit and the switching circuit.

Claims

1. An electric work machine comprising:

an electric motor that operates a work tool;

a rectification circuit converting a voltage to be applied to the electric motor from an alternating current voltage to a direct current voltage; and

a switching circuit controlling the electric motor,

wherein the rectification circuit is arranged upstream of the switching circuit in a circulation direction of air that cools the rectification circuit and the switching circuit.

2. The electric work machine according to claim 1,

wherein a casing that accommodates the rectification circuit and the switching circuit, a suction port provided in the casing and through which the air outside the casing is introduced into the casing, and an exhaust port provided in the casing and through which the air inside the casing is exhausted outside the casing are provided,

through a first circulation path of the air formed in the casing, the suction port and the exhaust port are communicated with each other, and

the rectification circuit is arranged closer to the suction port than the switching circuit in the first circulation path.

3. The electric work machine according to claim 2,

wherein an electrical component that controls the electric motor is provided in the casing, and

a distance from the suction port to the rectification circuit is shorter than a distance from the suction port to the switching circuit and a distance from the electrical component to the suction port.

4. The electric work machine according to claim 2,

wherein the rectification circuit is a bridge circuit including a plurality of diode elements, and

the switching circuit includes a plurality of switching elements.

5. The electric work machine according to claim 4,

wherein the first circulation path passes through between the plurality of switching elements.

6. The electric work machine according to claim 2,

wherein a first heat sink that transmits heat of the rectification circuit to the air, and a second heat sink that transmits heat of the switching circuit to the air are provided.

7. The electric work machine according to claim 2,

wherein a first guide unit that guides the air flowing in the first circulation path to the switching circuit is provided.

8. The electric work machine according to claim 7,

wherein the first guide unit is provided in the rectification circuit.

9. The electric work machine according to claim 6,

wherein the first heat sink includes a second guide unit that guides the air flowing in the first circulation path to the switching circuit.

10. The electric work machine according to claim 2,

wherein a direction of a flow of the air that cools the rectification circuit and a direction of a flow of the air that cools the switching circuit are the same in the first circulation path.

11. The electric work machine according to claim 2,

wherein the suction port includes a plurality of suction ports having different directions of the flow of the air to be introduced into the casing.

12. The electric work machine according to claim 4,

wherein the plurality of switching elements are arranged along a flow direction of the air in the first circulation path.

13. The electric work machine according to claim 2,

wherein a cooling fan that is rotated by power of the electric motor is provided in the casing, and

the air outside the casing is sucked into the casing when the cooling fan is rotated.

14. The electric work machine according to claim 13,

wherein a second circulation path in which the air, sucked into the casing by rotation of the cooling fan and cooling the electric motor, flows, is formed in the casing, and

the first circulation path and the second circulation path are in parallel to each other.

15. The electric work machine according to claim 13,

wherein a second circulation path in which the air, sucked into the casing by rotation of the cooling fan and cooling the electric motor, flows, is formed in the casing, and

the second circulation path is formed downstream of the first circulation path in the flow direction of the air in the casing.

16. The electric work machine according to claim 2,

wherein a substrate case to which the rectification circuit and the switching circuit are attached is provided in the casing.

17. The electric work machine according to claim 16,

wherein the substrate case includes a third guide unit that guides the flow direction of the air.