Control device for electric water pump

Patent metadata

Field	Value
Publication number	US-9695827-B2
Application number	US-201114115809-A
Country	US
Kind code	B2
Filing date	Jun 22, 2011
Priority date	Jun 22, 2011
Publication date	Jul 4, 2017
Grant date	Jul 4, 2017

Abstract

In an electric water pump for circulating cooling water of an engine mounted on a vehicle or similar, a time interval to switch energized phase of a pump motor is set to longer than a time interval during a normal flow rate control (during a flow rate control at a flow rate equal to or more than a flow rate where an electromotive force generated at a non-energized phase is detectable). In the case where a pump discharge pressure (or a water temperature of the cooling water) repeatedly increases and decreases in this extremely low flow rate state, it is determined that the electric water pump normally rotates as required. This allows providing the extremely low flow rate state between a water stop state and a water circulation state in a control for stop of water in an engine cooling system.

First claim

The invention claimed is:

1. A control device for an electric water pump that circulates cooling water through a cooling system of an engine, the control device comprising:
a rotation determining unit configured to determine that the electric water pump rotates as required by detecting that one of a discharge pressure of the electric water pump and a water temperature of the cooling water repeatedly increases and decreases when a rotation speed of the electric water pump is lower than a minimum detectable rotation speed,
wherein the minimum detectable rotation speed is a minimum rotation speed at which a detectable electromotive force is generated at a non-energized phase by rotation of the electric water pump.

2. The control device for the electric water pump according to claim 1 , wherein
the rotation determination of the electric water pump is performed when a circulation flow rate of cooling water by the electric water pump is equal to or less than a predetermined flow rate.

3. The control device for the electric water pump according to claim 1 , wherein
energization of the electric water pump is controlled by duty control, and the rotation determination of the electric water pump is performed in a case where a duty ratio of the duty control is equal to or less than a predetermined value.

4. The control device for the electric water pump according to claim 1 , wherein
the electric water pump includes (i) a rotor having an impeller, and (ii) a stator having a plurality of phases of coils disposed at a periphery of the rotor, the electric water pump being configured to rotate the rotor by sequentially switching a phase to be energized, among the plurality of phases, in the coils of the stator,
when the electric water pump transitions from a stopped state to a water circulation state, the electric water pump first enters a low flow rate state before entering a normal flow rate state, the low flow rate state being defined as a state in which the rotation speed of the electric water pump is lower than the minimum detectable rotation speed, and
a time interval for sequentially switching energization of the plurality of phases during the low flow rate state is set to be longer than a time interval for sequentially switching energization of the plurality of phases during the normal flow rate state, such that the rotation determination of the electric water pump is performed.

5. The control device for the electric water pump according to claim 4 , wherein
the time interval for switching energization of the plurality of phases is set longer to an extent that a phenomenon occurs, the phenomenon being one of a discharge pressure of the electric water pump and a water temperature of the cooling water repeatedly increasing and decreasing.

Assignees

• Araki Yukari
• Shintani Osamu
• Shikida Takasuke
• Toyota Motor Co Ltd

Inventors

• Araki Yukari
• Shintani Osamu
• Shikida Takasuke

Classifications

• F01P2060/08

  Cabin heater · CPC title

• F01P7/16

  by thermostatic control · CPC title

• F04D15/0066

  by changing the speed, e.g. of the driving engine · CPC title

• F01P11/18

  concerning coolant pressure, coolant flow, or liquid-coolant level · CPC title

• F04D15/0094 Primary

  Indicators of rotational movement · CPC title