1、 WORLDWIDE ENGINEERING STANDARDS Test Procedure GMW14786 Heater Coolant Flow and Resistance in the Vehicle Copyright 2011 General Motors Company All Rights Reserved July 2011 Originating Department: North American Engineering Standards Page 1 of 6 1 Scope Note: Nothing in this standard supercedes ap
2、plicable laws and regulations. Note: In the event of conflict between the English and domestic language, the English language shall take precedence. 1.1 Purpose. Determination of the flow of coolant through the heater core and measurement of the resistance of the heater core in order to evaluate the
3、 heater flow and the resulting heater output. 1.2 Foreword. The heater flow shall also be measured in the thermostat control range, particularly in the case of new designs, in order to enable the detection of drops in heater flow due to changes in the coolant circuit. 1.3 Applicability. For all wate
4、r-cooled engines. 2 References Note: Only the latest approved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications. None 2.2 GM Standards/Specifications. None 3 Resources 3.1 Facilities. Test stand for fixing the test setup. 3.2 Equipment. 3.2.1 When Using a Flo
5、w Meter (Direct Measurement). 3.2.1.1 Flow Meter. A flow meter, with a flow resistance that can be neglected. 3.2.1.2 T-fittings. Two (2) T-fittings, one in the heater core in line and one in the heater core out line, for the connection of the differential pressure sensor. The inside diameter shall
6、be the same as that of the heater hose. Pressure is tapped in the ring duct. See Figure 1 and Figure 2. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERIN
7、G STANDARDS GMW14786 Copyright 2011 General Motors Company All Rights Reserved July 2011 Page 2 of 6 1 Heater core 2 Connection for differential measurement line 3 Heater core out line 4 Heater core in line 5 Connection for differential measurement line Figure 1: T-fittings in Heater Core In Line an
8、d Out Line 1 Heater hose inside diameter 2 Bore 4 equal space holes in ring duct, diameter () = 2 mm Figure 2: T-fitting with Soldered-on Ring Duct for Improved Pressure Measurement Note: The four (4) bore holes in the ring duct shall be free from burrs, but shall not be beveled. The installation of
9、 the flow meter and T-fittings can be seen in Figure 1. The differential pressure shall be measured in a straight part of the hose 120 mm in front of the heater core connection tubes. 3.2.1.3 Differential Pressure Sensor. Attention shall be paid within an appropriate measurement range. The same inst
10、ruments shall be used for the calibration of the pressure drop line chart of the heater core and the following measurement of the flow using the pressure drop line chart. 3.2.1.4 Engine Speed Sensor. Measuring device for gasoline and diesel engines. mm mm mm mm mm 8 mm Copyright General Motors Compa
11、ny Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14786 Copyright 2011 General Motors Company All Rights Reserved July 2011 Page 3 of 6 3.2.1.5 Temperature Measuring Dev
12、ice. Temperature measuring device to record coolant temperatures (3 measuring points). 3.2.1.6 Coolant. 50% antifreeze protection, 50% water. 3.2.2 Indirect Method Using an External Test Bench. Use the test bench to determine: Equipment analogous to that described in paragraphs 3.2.1.2 to 3.2.1.6 is
13、 required for the measurement of the differential pressure in the vehicle. 3.2.3 Indirect Measurement in the Vehicle. Equipment analogous to that described in paragraph 3.2.1. 3.3 Test Vehicle/Test Piece. Test vehicle equipped as specified, or a complete engine block. 3.4 Test Time. Not applicable.
14、Calendar time: days Test hours: hours Coordination hours: hours 3.5 Test Required Information. Not applicable. 3.6 Personnel/Skills. Not applicable. 4 Procedure 4.1 Preparation. 4.1.1 Ensure that the vehicle engine and cooling systems correspond to preferred status. 4.1.2 Check that the correct heat
15、er core is installed. 4.1.3 Install a tested thermostat. The opening values and leakage water quantity must remain within the specified tolerances. 4.1.4 Install Temperature Sensors. In the heater core in line and heater core out line, and In the radiator inlet to record the opening of the thermosta
16、t. 4.1.5 Check the installation of the two T-fittings to ascertain the pressure drop at the heater core. The T-fittings shall be inserted in a straight hose section 120 mm in front of the heater core. If the heater core is connected by means of quick connections, these shall also be included in the
17、measurement (partially high resistance). 4.1.6 Install flow meter, if applicable. 4.1.7 Connect the differential pressure meter. 4.1.8 Fill the cooling system with the provided coolant. See 3.2.1.6. Care shall be taken to ensure that no air enters the cooling-heating system during filling. In the ca
18、se of critical systems, presence of no air shall be checked by means of sight glasses in the heater circuit. 4.2 Conditions. 4.2.1 Environmental Conditions. Not applicable. 4.2.2 Test Conditions. Deviations from the requirements of this standard shall have been agreed upon. Such requirements shall b
19、e specified on component drawings, test certificates, reports, etc. 4.3 Instructions. 4.3.1 Methods of Determining the Heater Flow. There are two methods to determine the heater flow: 1. Direct measurement, by means of a flow meter, and 2. Indirect measurement, by means of differential pressure at t
20、he heater core, for which characteristic pressure drop to coolant flow is known. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14786 Co
21、pyright 2011 General Motors Company All Rights Reserved July 2011 Page 4 of 6 Direct measurement using a flow meter is the simplest method, but is not always possible due to space constraints. Since the confined space in some vehicle models does not allow measurements without major alterations to th
22、e hosing, the measurements may be performed on an engine test bench or an engine block. 4.3.1.1 For direct measurement with flow meter and simultaneous recording of the static pressure drop at the heater core, the flow meter shall be installed in the housing towards the heater core. If the installat
23、ion of the flow meter generates major alterations (additional pressure drop) at the heating circuit, the indirect method described in paragraph 4.3.1.2 shall be employed. The static pressure drop at the heater core, possibly with quick connections, shall always be determined. For test assembly, see
24、Figure 3. 4.3.1.2 For indirect measurement, measure differential pressure at the heater core. In this test procedure, the heater flow (V) with respect to the engine speed is ascertained indirectly by measuring the static pressure drop at the heater core (pheater core) in which the function is known.
25、 The characteristic can be ascertained at the engine or at an external test bench. 4.3.1.2.1 Determination of the characteristic in the vehicle (indirect measurement). Using a flow meter, (which can be installed neglecting the original hosing in the heating circuit), and the differential pressure se
26、nsor at the heater core (see Figure 1) the characteristic of the pressure drop at the heater core is determined by variation of the engine speed. Afterward, the flow meter is removed from the heater circuit and the original hosing of the coolant lines re-established, while the differential pressure
27、sensor remains in the system. The pressure drop at the heater core shall then be determined for the selected engine speeds. Using the first determined characteristic the flow rate with respect to the engine speed (nMot) can be established: 4.3.1.2.2 Determination of the characteristic on an external
28、 test bench (indirect measurement). The dependence of shall be measured on an external test bench at coolant temperature of 75 3 C. Care shall be taken with respect to the position of the differential pressure sensor at the heater core; the same installation position should be used in the vehicle. T
29、he pressure drop at the heater core for the selected engine speeds shall then be determined in the vehicle using the same measuring distance and the flow shall be assigned using the characteristic of the heater core. Copyright General Motors Company Provided by IHS under license with General Motors
30、CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14786 Copyright 2011 General Motors Company All Rights Reserved July 2011 Page 5 of 6 1 Heater core 2 Flow meter 3 Thermocouple or resistance-temperature device 4 Heater co
31、re in line 5 Heater core out line 6 Differential pressure sensor 7 Engine speed sensor 8 Radiator 9 Thermocouple or resistance-temperature device 10 Thermostat Figure 3: Test Assembly for Determination of Heater Flow and p heater core 4.3.2 The coolant flow through the heater core shall be determine
32、d using the production intent thermostat. 4.3.2.1 With a closed thermostat, the measurement shall be applied in a temperature range of +70 to +80 C in the heater core in line at theater 10 C. Once the coolant has reached +70 C in the heater core in line, the engine speed shall be increased in stages
33、 from idle speed. In the event that the heater core inlet temperature exceeds +80 C during the test, it is required to cool down the coolant and continue the measuring sequence. The engine shall be driven at the following speeds: Idle, 1000 rpm, 1500 rpm, 2000 rpm and 3000 rpm minimum. 4.3.2.2 Withi
34、n the thermostat control range, when the opening temperature of the thermostat is reached, the heater flow is determined at a constant engine speed. Measurement shall continue until the radiator is in full operation, at the following engine speeds: Idle, 1000 rpm, 1500 rpm, 2000 rpm and 3000 rpm (mi
35、nimum). The temperature should rise at a rate of 4 C/minute. The temperature rise shall be regulated by means of a radiator fan. Note: The heater flow measurement in the thermostat control range shall be performed in order to discover whether any serious drops in the heater flow occur as a result of
36、 changes in the cooling circuit when the thermostat opens. If the flow conditions are known, then a measurement of this kind is not required. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without licens
37、e from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14786 Copyright 2011 General Motors Company All Rights Reserved July 2011 Page 6 of 6 5 Data 5.1 Calculations. 5.1.1 Recording of Data. Record the following data: Engine speed (rpm) Coolant flow rate, in Liters per minute (L/minute) Pressure drop
38、between heater core inlet and heater core outlet, in kilopascals (kPa) Coolant temperature, in degrees Celsius (C): Heater core in Heater core out Radiator in 5.2 Interpretation of Results. Not applicable. 5.3 Test Documentation. 5.3.1 The results recorded during the tests shall be analyzed and incl
39、uded in the test report. 5.3.2 Representation. The results of the measurement shall be graphed with engine speed on the x-axis and assembled in a test report calling up this test procedure. 6 Safety This standard may involve hazardous materials, operations, and equipment. This standard does not prop
40、ose to address all the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 7 Notes 7.1 Glossary. Not applicable. 7.2 Acronyms, Abbre
41、viations, and Symbols. pheater core Static Pressure Drop at the Heater Core theater Temperature Change at the Heater Diameter nMot Engine Speed V Heater Flow 8 Coding System This standard shall be referenced in other documents, drawings, etc., as follows: Test to GMW14786 9 Release and Revisions Thi
42、s standard was originated in November 2005. It was first approved by the HVAC Module Global Subsystem Leadership Team in March 2006. It was first published in March 2006. Issue Publication Date Description (Organization) 1 MAR 2006 Initial publication. 2 JUL 2011 Update for 5 Year Refresh. (HVAC Module GSSLT) Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
