GB2317035A

GB2317035A - Determining wear of internal combustion engines

Info

Publication number: GB2317035A
Application number: GB9716478A
Authority: GB
Inventors: Kevin D Ehrenhardt; James W Landes; Prasad V Parupalli; Richard D Rathe
Original assignee: Caterpillar Inc
Current assignee: Caterpillar Inc
Priority date: 1996-08-09
Filing date: 1997-08-04
Publication date: 1998-03-11
Also published as: DE19734714A1; GB9716478D0

Abstract

An apparatus for testing an internal combustion engine 35 and predicting wear and hence future engine performance includes a control microprocessor 20 connected to a memory 25 and storing therein historical engine performance data. The data is indicative of historical engine load. An average historical engine load is calculated by a communication device 32 and compared to a predetermined value. That comparison determines whether testing by dynamometer is necessary to predict future engine performance.

Description

2317035 APPARATUS AND METHOD FOR TESTING THE PERFORMANCE OF INTERNAL

COMBUSTION ENGINES 5 The present invention relates generally to an apparatus and method for testing the performance of internal combustion engines, and more particularly to an apparatus and method for estimating what power levels the engine was used at in the past.

Engine manufacturers generally warranty new engines for a predetermined period of time. Sometimes manufacturers will allow customers to extend that warranty for an additional charge. Similarly, customers sometimes request manufacturers or dealerships to provide a warranty on a used engine whose original warranty, and extended warranty if any, has expired. In such cases, the manufacturer or dealership would like to have some indication of how the previous users ran the engine to determine the approximate condition of the engine.

one previous apparatus and method of accomplishing this task has measured the compression of an engine cylinder. The measured cylinder compression is then compared against a predetermined value to predict future engine performance. While this procedure may sometimes be acceptable, it requires that a sensor be physically connected to the cylinder by a skilled technician. The procedure is also time consuming.

Another way to predict future performance is to perform a dynamometer test to determine the horsepower output and fuel economy of the engine. The horsepower output and fuel economy is then compared to acceptable limits for the engine. If the engine is producing horsepower levels significantly higher than those for which it is rated, then it may experience higher stress levels, that might shorten its life span. The dynamometer test is a useful tool in this analysis. However, it too requires a skilled technician and relatively sophisticated testing tools to perform the test.

It would be desirable to develop-an apparatus and method for testing an internal combustion engine to assist in predicting future performance that could sometimes avoid the necessity for sophisticated tools, expensive procedures and skilled technicians.

Brief Description of the Drawings

Figure 1 is a block diagram of a preferred embodiment of an electronically controlled engine; and Figure 2 is a flowchart of the software control of a preferred embodiment of the present invention; The present invention includes an apparatus and method of predicting the future performance of an internal combustion engine. The apparatus includes a microprocessor connected to a memory device having historical engine performance data stored therein. A communications device is connectable to an input/output port. The communication device retrieves selected historical engine data and calculates predicted past engine wear.

In another embodiment of the present invention, a method for predicting past engine wear includes retrieving engine historical data. The engine historical data includes a parameter indicative of historical engine load. The method compares an average historical engine load to a predetermined value and produces an output indicative of the comparison, which in general is indicative of the past engine wear.

These and other aspects and advantages of the present invention will become apparent upon reading the following detailed description of a preferred embodiment in conjunction with the drawings and appended claims.

The following is detailed description of a preferred best mode embodiment of the present invention. The following description provides sufficient detail to permit someone skilled in the art to make and use the invention. However, the present invention is not limited to the single preferred embodiment disclosed herein. on the contrary, the present invention encompasses all those devices and methods that fall within the scope of the appended claims and equivalents thereof. Throughout the description and the drawings like reference numbers will be used to refer to like elements.

Referring first to Figure 1, a block diagram of a preferred embodiment of an electronic engine and vehicle control system 10 for use with an embodiment of the present invention is shown. The electronic control 10 preferably includes an electronic control module 15, which includes a microprocessor 20 connected to a memory device 25 and an inputloutput port 30. In a preferred embodiment, the microprocessor is a Motorola MC68HC11 manufactured by Motorola Corp. However, other microprocessors could be readily and easily used without deviating from the scope of the present invention.

As is known to those skilled in the art, the memory device 25 depicted in Figure 1 generally stores both software instructions and data. The software instructions stored in the memory device 25 include, among other things, the specific code that controls the engine 35. The data stored in the memory 25 may either be permanently stored or may be temtorarily written to the memory 25 by the microprocessor 20.

The microprocessor 20 is therefore generally able to both read data and software instructions from, and write to, the memory 25.

is Also known to those skilled in the art is input signal conditioning/buffering circuitry and output driver circuitry 45. As shown in Figure 1, the microprocessor 20 is connected to inputloutput buffer and driver circuitry 45. The inputloutput buffer and driver circuitry 45 is an interface, buffering and signal conditioning circuit between the microprocessor and the communication bus 40. Signals generated by the microprocessor 20 are transmitted over the communications bus 40. In a preferred embodiment the communications bus 40 satisfies the communications protocols defined by SAE J1587. However, other communications schemes could be readily and easily substituted without deviating from the scope of the present invention as defined by the appended claims.

The communications bus 40 is connected to various sensors and actuators, such as vehicle and other sensors 60, actuators 55 and sensors 50 associated with a compression ignition engine 35.

Typically, the actuators 55 will include fuel injector solenoids that cause engine fuel injectors to open and inject fuel into individual engine cylinders based on a fuel command produced by the microprocessor 20. As is known to those skilled in the art, the timing and quantity of fuel injected into a cylinder is dependent upon a variety of factors including engine rating, emissions requirements, engine speed, and throttle demand, among others. The factors considered in determining the specific timing and quantity of fuel injected into an engine are well known to those skilled in the art. The present invention-is applicable to a variety of compression ignition engines irrespective of specific timing and quantity of fuel injected. Since the present invention does not depend on a specific timing nor on injection of a specific quantity of fuel, they are not described further herein.

Also connected to the communication bus 40 is an input/output port 30. The input/output port 30 is a communication port that permits a technician, other service personnel, or fleet manager to connect a communication device 32 to the port 30 to enter data or commands into memory 25 or to download data or commands from memory 25. In a preferred embodiment, the communication device is a hand held service tool, Model No. 8T8697 available from Caterpillar Inc., Peoria, Ill. However, other programming devices, including personal computers could be programmed to be compatible with the communication bus 40 and could be used in connection with the present invention.

one specific engine sensor used in a preferred embodiment of the present invention is an engine speed sensor of the type generally disclosed in U.S. Patent No. 4,972,332 issued to Luebbering et al.

However, other types of engine speed sensors could be readily and easily used without deviating from the scope of the present invention. The engine speed sensor is one of many engine sensors that is generically represented by block 50.

A vehicle sensor 60 that is used in a preferred embodiment of the present invention is a vehicle speed sensor. Typically the vehicle speed is calculated using a transmission output speed sensor and the stored axle ratio and tire size. such calculations are well known in the art. Many suitable transmission output speed sensors are known in the art, any one of which may be readily and easily implemented in connection with the present invention. In a preferred embodiment, the transmission output speed sensor is a sensor as disclosed in U.S. Pat. No.

is 4,972,332 issued to Luebbering.

Referring now to Figure 2, a flowchart of a preferred embodiment of software control of the present invention is shown, The flowchart illustrates an exemplary set of instructions for performing the preferred control. However, as is know to those skilled in the art,'the functionality of specific blocks, or the order in which the functions of the blocks are performed, can sometimes be changed without affecting the overall functionality of the control.

Thus, it is expected that other block diagrams illustrating similar software control will fall within the scope of the present invention as defined by the appended claims.

The program depicted in the flowchart of Figure 2 is particularly well adapted for use with the MC68HClI microprocessor and associated components described above, although any suitable microprocessor may be utilized in practicing an embodiment of the present invention. These flowcharts constitute a complete and workable design of the preferred software program, and have been reduced to practice on the Motorola 68000 series microprocessor system. The software program may be readily coded from these detailed flowcharts using the instruction set associated with this system, or may be coded with the instructions of any other suitable conventional microprocessors. The process of writing software code from flowcharts such as these is a mere mechanical step for one skilled in the art.

Software control of the present invention begins in block 200 and passes to block 210. In block 210, the communications device 32 reads a register in memory corresponding to the total number of engine hours (i.e., the total number of hours the engine has been in operation). In a preferred embodiment, the microprocessor determines that the engine is running by inputting a signal from the engine speed sensor and determining that the engine speed is greater than a predetermined value (typically an idle speed value).

While the engine speed exceeds the predetermined value, the microprocessor causes a register corresponding to total engine hours to increment, thereby logging and keeping track of the total number of engine hours. If, in block 210, the total engine hours exceeds a first predetermined total hour value T1 then program control passes to block 230, otherwise program control passes to block 220. In a preferred embodiment, the first predetermined total hour value T1 corresponds to 6,000 hours. However, other values could be readily and easily substituted without deviating from the spirit and scope of the present invention as defined by the appended claims.

In block 220, the communications device 32 reads a register in memory corresponding to the total number of miles driven by the vehicle equipped with the engine. In a preferred embodiment, the microprocessor 20 logs the total number of vehicle miles by tracking the output of a transmission output speed sensor and retrieving the tire size of the vehicle and the rear axle gear ratio from memory, both of which are stored in memory. From those values the microprocessor then calculates the number of miles driven by the vehicle and stores that total in a register in memory. If, in block 220, the total vehicle miles is greater than a first predttermined total vehicle mile value M1, then program control passes to block 230. otherwise, program control passes to block 300. In a preferred embodiment, the first predetermined total vehicle mile value is 300,000 miles. However, other values could be readily and easily substituted without deviating from the spirit and scope of the present invention as defined by the appended claims.

If program control passes to block 300 then the number of total engine hours and the number of total miles driven is sufficiently small to assume that the engine has not had significant wear. In this case, the communication device 32 indicates through a display, printout or other means that the engine does not need to be dynamometer tested to qualify for possible warranty coverage.

If on the other hand, program control passed to block 230, then the engine had sufficient hours, or the vehicle had sufficient miles (or both) to warrant further inspection. Then, in block 230, the program control determines whether the total engine hours exceeds a second predetermined total hour value T2. If so, then program control passes to block 250 where the communications device 32 displays or otherwise signifies to the operator that a dynamometer test is required to determine whether a warranty will be offered with the engine. Otherwise, if the total engine hours is less than the second predetermined total hour value T2, then program control passes to block 240. In a preferred embodiment, the second predetermined total hour value T2 corresponds to 13,000 hours. However, other values could be readily and easily substituted without deviating from the spirit and scope of the present invention as defined by the appended claims.

In block 240, if the total vehicle miles is greater than a second predetermined total vehicle mile value M2, then program control passes to block 250 where the communications device 32 displays or otherwise signifies to the operator that a dynamometer test is required to determine whether a warranty will be offered with the engine. otherwise, program control passes to block 260. In a preferred embodiment, the second predetermined total vehicle mile value M2 is 650,000 miles. However, other values could be readily and easily substituted without deviating from the spirit and scope of the present invention as defined by the appended claims.

In block 260, the communications device 32 retrieves an average fuel rate from a register in memory. As is known to those skilled in the art, the microprocessor calculates a fuel delivery command based,on a variety of factors including the throttle position, cruise control engagement, temperature, and fuel delivery limits, among others. The fuel delivery command determines how much fuel is injected by the fuel injectors. In a preferred embodiment, the microprocessor calculates an average fuel rate by keeping a running average of the fuel delivery command and storing that value in memory. In block 260 the communications device 32 retrieves the average fuel rate. Program control then passes to block 270.

In block 270, the communications device compares the average fuel rate against an average fuel rate limit for that particular engine. In a preferred embodiment, the fuel rate limit is about 65% of the maximum fuel rate for that engine. The average fuel rate is an indication of how hard the engine has been run and, therefore, the cumulative stress and wear to which it has been subjected. If the average fuel rate exceeds the average fuel rate limit, then program control passes to block 250, where the communications device 32 displays or otherwise signifies to the operator that a dynamometer test is required to is determine whether a warranty will be offered with the engine. If, on the other hand, the average fuel rate is less than the average fuel rate limit, then program control passes to block 300 where the communication device 32 indicates through a display, printout or other means that the engine does not need to be dynamometer tested to qualify for possible warranty coverage.

once the communications device 32 has displayed either the message of block 250 or of block 300 program control passes to block 310 where the program control ends.

The above described preferred embodiment of the invention provides a useful apparatus and method for reducing the number of dynamometer tests that must be performed on used engines to predict whether they have been subjected to excessive wear. To begin the test, an operator will connect the communications device 32 to the inputloutput port 30 and will initiate a test through An appropriate input on the communications device 32. The operator will then wait for a display stating whether the dynamometer test is required or not. In this manner, an untrained operator can easily determine whether a dynamometer test is required. This screening procedure will significantly reduce the number of dynamometer tests that would otherwise be required to be performed to assess whether the engine might have excessive wear.

Claims

CLAIMS We claim:

1. An apparatus for predicting wear on an internal combustion engine, comprising:

microprocessor; memory device connected to said microprocessor; an inputloutput port communicating with said microprocessor; a communications device connected to said inputloutput port; wherein said microprocessor stores historical engine performance data in said memory; and is wherein said communications device retrieves selected historical engine performance data, calculates predicted engine wear and outputs a message indicative of a predicted engine wear.

2. The apparatus according to claim 1, wherein said historical engine performance data includes:

total engine hours; total vehicle miles; and average fuel rate.

3. The apparatus according to claim 2, wherein: said communications device calculates said predicted engine wear using a comparison between said total engine hours and a first predetermined total hour value and a comparison between said total vehicle miles and a first predetermined total vehicle mile value.

4. The apparatus according to claim 2, wherein:

said communication device calculates an average fuel rate for the engine, retrieves an average fuel rate limit from memory, and calculates said predicted engine wear based on a comparison of said average fuel rate and said average fuel rate limit.

5. The apparatus according to claim 3, wherein:

said communication device calculates said predicted engine wear using a comparison between said total engine hours and a second predetermined total hour value and a comparison between said total vehicle miles and a second predetermined total vehicle mile value.

6. The apparatus according to claim 5, wherein:

said communications device calculates an average fuel rate for the engine, retrieves an average fuel rate limit from memory, and calculates said predicted engine wear based on a comparison of said average fuel rate and said average fuel rate limit in response to said total engine hours being greater than said first predetermined total hour value and less than said second predetermined total hour value and in response to said total vehicle miles being greater than said first predetermined total vehicle mile value and less than said second predetermined total vehicle mile value.

7. A communications device for use with a vehicle having an internal combustion engine, said engine being controlled by an electronic control module and connected to an inputloutput port, said electronic control module having stored therein historical engine performance data, said communications device comprising: a display device; an input device; and wherein said communications device is connectable to said input/output port and retrieves said historical data, calculates and displays an output indicative of probable engine wear._

8. A method for reducing the number of dynamometer tests when predicting engine wear, said method comprising:

is retrieving engine historical data; calculating a value indicative of average engine load; comparing said average engine load to an average engine load limit; and producing an output indicative of said comparison, wherein said output is a function of said predicted engine wear.