Electric Construction Machine

• US 20150231974A1
• Filed: 06/19/2013
• Published: 08/20/2015
• Est. Priority Date: 08/21/2012
• Status: Active Grant

• Current Assignee: Hitachi Construction Machinery Tierra Co.,Ltd. (Hitachi Construction Machinery (China) Co., Ltd.)
• Original Assignee: Hitachi Construction Machinery Company Limited (Hitachi, Ltd.)
• Inventors: Yunoue, Masayuki, Takishita, Tatsuo, Kurikuma, Hajime
• Granted Patent: US 9,889,750 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B60L 50/51 characterised by AC-motors
• CPC Class Codes: B60L 50/53 in combination with an external power supply, e.g. from overhead contact lines
• CPC Class Codes: B60L 53/00 Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles
• CPC Class Codes: E02F 3/325 Backhoes of the miniature type
• CPC Class Codes: E02F 3/964 of several tools mounted on one machine E02F3/962 takes precedence
• CPC Class Codes: E02F 9/207 of the type electric propulsion units, e.g. electric motors or generators
• CPC Class Codes: E02F 9/2091 Control of energy storage means for electrical energy, e.g. battery or capacitors energy recovery arrangements in hydraulic or pneumatic drives E02F9/2217
• CPC Class Codes: E02F 9/2285 Pilot-operated systems
• CPC Class Codes: E02F 9/2296 Systems with a variable displacement pump
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 90/14 Plug-in electric vehicles

Abstract

Provided is an electric construction machine adapted to prevent an electric current, after flowing in via a junction at which power transmission systems join together, from flowing into at least one connector to which an external power supply is not connected.

Power transmission systems 71A, 71B, 71C connected to connectors 59A, 59B, 59C are all caused to join with a common system 73 at a junction before being connected to a control unit 35. The power transmission systems 71A, 71B, and 71C include switches 74Aa, 74Ab, 74Ba, 74Bb, 74Ca, 74Cb. In relay circuits 75A, 75B, 75C, when a plug for an external power supply is connected to corresponding one of the connectors 59A, 59B, 59C, connection of the corresponding connector connection detecting terminals and plug connection detecting terminals energizes a coil of the corresponding control relay (either 76A, 76B, or 76C), then after switching contact points of the corresponding control relay to a closed state, energizes coils of the corresponding switches via the contact points, and switches contact points of the corresponding switches to a closed state.

Claims

1. An electric construction machine comprising:

an electric motor;

a hydraulic pump driven by the electric motor;

hydraulic actuators, each driven by a hydraulic fluid delivered from the hydraulic pump;

an internal battery that is an electric power supply source for the electric motor;

a plurality of connectors to which respective plugs for a plurality of kinds of external power supplies are adapted to be connected;

a plurality of power transmission systems each connected to one of the plurality of connectors; and

a battery charger to which the plurality of power transmission systems are connected via one common system, the battery charger being configured so that when any one of the plurality of connectors is connected to corresponding one of the plugs for the external power supplies, the battery charger supplies, to the internal battery, electric power supplied from the corresponding external power supply,

wherein the electric construction machine further comprises;

a plurality of switches, each disposed in one of the plurality of power transmission systems and each associated with one of the plurality of connectors;

a detection block that detects whether one of the plurality of connectors has been connected to corresponding one of the plugs for the external power supplies or whether one of the connectors has been selected for connection to corresponding one of the plugs for the external power supplies; and

a switching control block that conducts switching control so that among the plurality of switches, only the switches associated with the connector detected by the detection block will close and all the other switches will open.

2. The electric construction machine according to claim 1, wherein:

the detection block includes connector connection detecting terminals each disposed in one of the plurality of connectors and each connected to one of plug connection detecting terminals disposed in the plugs for the external power supplies;

the switching control block is a plurality of relay circuits that each include a control relay associated with a combination of one of the connectors and one of the switches; and

the plurality of relay circuits are each constructed so that when the plug for one of the external power supplies is connected to the corresponding one of the plurality of connectors, connection of the corresponding connector connection detecting terminals and plug connection detecting terminals energizes a coil of the corresponding control relay, then after switching contact points of the corresponding control relay to a closed state, energizes coils of the corresponding switches via the contact points, and switches contact points of the corresponding switches to a closed state.

3. The electric construction machine according to claim 1, wherein:

a sliding plate is disposed that while selectively opening one of the plurality of connectors so as to be connectable to the corresponding one of the plugs for the external power supplies, blocks the remaining connectors so as to be unconnectable to the plugs for the external power supplies;

the detection block includes a limit switch that detects a sliding position of the sliding plate; and

the switching control block is a controller that conducts switching control so that among the plurality of switches, only the switches associated with a connector determined to be connectable to the corresponding plug for the external power supply will close and all the other switches will open.