DETERMINATION OF ENGINE ROTATIONAL SPEED BASED ON CHANGE IN CURRENT SUPPLIED TO ENGINE STARTER

• US 20090183557A1
• Filed: 01/16/2009
• Published: 07/23/2009
• Est. Priority Date: 01/21/2008
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Ono, Hiroaki
• Granted Patent: US 7,913,548 B2
• Time in Patent Office: Days
• US Class Current: 73/114.250
• CPC Class Codes: F02D 2041/228 Warning displays
• CPC Class Codes: F02D 2200/503 Battery correction, i.e. corrections as a function of the state of the battery, its output or its type
• CPC Class Codes: F02D 41/0097 using means for generating speed signals
• CPC Class Codes: F02D 41/062 for starting F02D41/061 takes precedence
• CPC Class Codes: F02N 19/005 Aiding engine start by starting from a predetermined position, e.g. pre-positioning or reverse rotation
• CPC Class Codes: F02N 2019/008 the engine being stopped in a particular position
• CPC Class Codes: F02N 2200/045 Starter temperature or parameters related to it
• CPC Class Codes: F02N 2300/104 Control of the starter motor torque

Abstract

An engine rotational speed determining device is disclosed which includes a signal inputting means and a rotational speed determining means. The signal inputting means inputs a signal that indicates current supplied to an electric motor, which starts an internal combustion engine, during a starting operation of the engine by the motor. The rotational speed determining means determines a rotational speed of the engine in the starting operation based on a change in the current indicated by the signal input by the signal inputting means.

Claims

1. An engine rotational speed determining device comprising:

a signal inputting means for inputting a signal that indicates current supplied to an electric motor, which starts an internal combustion engine, during a starting operation of the engine by the motor; and

a rotational speed determining means for determining a rotational speed of the engine in the starting operation based on a change in the current indicated by the signal input by the signal inputting means.

2. The engine rotational speed determining device further comprising:

a relaxation process performing means for performing a relaxation process for the signal input by the inputting means to eliminate the influence of electrical noise included in the signal; and

a relaxation process resetting means for resetting the relaxation process at a timing when the current indicated by the signal has decreased, after an initial rapid increase thereof, to become not higher than a predetermined threshold,

wherein the rotational speed determining means determines the rotational speed of the engine based on the signal that has received the relaxation process which is performed by the relaxation process performing means and reset by the relaxation process resetting means.

3. An engine starting possibility predicting device comprising:

a signal inputting means for inputting a signal that indicates current supplied to an electric motor, which starts an internal combustion engine, during each of a plurality of starting operations of the engine by the motor;

a rotational speed determining means for determining a rotational speed of the engine in each of the starting operations based on a change in the current indicated by the signal input by the signal inputting means;

a torque determining means for determining a torque of the motor in each of the starting operations based on the change in the current indicated by the signal input by the signal inputting means; and

a possibility predicting means for predicting, based on the rotational speeds of the engine and the torques of the motor determined by the rotational speed determining means and the torque determining means, a possibility of the motor to successfully start the engine in an upcoming starting operation of the engine.

4. The engine starting possibility predicting device as set forth in claim 3, further comprising a rotational speed predicting means for predicting a rotational speed of the engine in the upcoming starting operation based on the rotational speeds of the engine and the torques of the motor determined by the rotational speed determining means and the torque determining means,

wherein when the rotational speed of the engine in the upcoming starting operation predicated by the rotational speed predicting means is greater than or equal to a predetermined value, the possibility predicting means predicts that it is possible for the motor to successfully start the engine in the upcoming starting operation.

5. The engine starting possibility predicting device as set forth in claim 4, wherein the motor is powered by a battery, and wherein the rotational speed predicting means predicts the rotational speed of the engine in the upcoming starting operation in the following way:

defining a two-dimensional coordinate plane, where one coordinate axis indicates rotational speed of the engine and the other coordinate axis indicates torque of the motor;

determining, on the two-dimensional coordinate plane, a friction curve based on the rotational speeds of the engine and the torques of the motor determined by the rotational speed determining means and the torque determining means, the friction curve representing friction of the engine;

determining, on the two-dimensional coordinate plane, a performance curve of the motor based on a State of Charge (SOC) of the battery, the performance curve representing the performance of the motor at the SOC of the battery; and

predicting the rotational speed of the engine in the upcoming starting operation as the rotational speed of the engine at an intersection point between the friction curve and the performance curve of the motor.

6. An engine friction estimating device comprising:

a signal inputting means for inputting a signal that indicates current supplied to an electric motor, which starts an internal combustion engine, during each of a plurality of starting operations of the engine by the motor;

a rotational speed determining means for determining a rotational speed of the engine in each of the starting operations based on a change in the current indicated by the signal input by the signal inputting means;

a torque determining means for determining a torque of the motor in each of the starting operations based on the change in the current indicated by the signal input by the signal inputting means; and

an engine friction estimating means for estimating friction of the engine based on the rotational speeds of the engine and the torques of the motor determined by the rotational speed determining means and the torque determining means.

7. The engine friction estimating device as set forth in claim 6, wherein the engine friction estimating means estimates the friction of the engine in the form of an estimated value of the friction.

8. The engine friction estimating device as set forth in claim 7, wherein the engine friction estimating means determines the estimated value of the friction in the following way:

defining a two-dimensional coordinate plane, where one coordinate axis indicates rotational speed of the engine and the other coordinate axis indicates torque of the motor;

determining, on the two-dimensional coordinate plane, a friction curve based on the rotational speeds of the engine and the torques of the motor determined by the rotational speed determining means and the torque determining means, the friction curve representing the friction of the engine; and

determining the estimated value of the friction as the torque of the motor at the point on the friction curve where the rotational speed of the engine is equal to a predetermined value.

9. An engine automatic stop control device comprising:

a signal inputting means for inputting a signal that indicates current supplied to an electric motor, which starts an internal combustion engine, during each of a plurality of starting operations of the engine by the motor;

a rotational speed determining means for determining a rotational speed of the engine in each of the starting operations based on a change in the current indicated by the signal input by the signal inputting means;

a torque determining means for determining a torque of the motor in each of the starting operations based on the change in the current indicated by the signal input by the signal inputting means;

an engine friction estimating means for estimating friction of the engine based on the rotational speeds of the engine and the torques of the motor determined by the rotational speed determining means and the torque determining means; and

a controlling means for controlling an automatic stop of the engine based on the friction of the engine estimated by the engine friction estimating means.