Hunan Xiangyi Power Testing Instrument Co., Ltd.

According to JB/T6876-93 standard, JC type sensors are divided into 0.1 and 0.2 grades based on torque measurement accuracy. The 0.1 grade has a static calibration error of ±0.1%FS, and the 0.2 grade has a static calibration error of ±0.2%FS.

Yes. Simply fix the sensor output shaft, start the small motor on the sensor, and you can perform static torque measurement. For example, the locked-rotor torque of a motor can be measured using this method. However, note that the static impact torque should not exceed 300% of the rated torque.

The JC-type sensor ensures accurate measurement within a range of 120% of the rated torque, and allows for transient impacts up to 300% of the rated torque without damage.

The sensor's initial phase has changed (increased). Measuring the sensor's initial phase with a torque meter reveals a significant difference (increase) compared to the factory record. The reason is:

1. Internal gear looseness

2. Excessive impact torque causing irreversible deformation of the elastic shaft. Factory repair is recommended.

The JC type torque sensor is a transmission type dynamometer; it only transmits torque (power) and does not absorb torque (power). Therefore, the JC type sensor must be installed between the power source and the load. There are many ways to load, which should be selected according to user needs. Common methods include hydraulic dynamometers, electric dynamometers, eddy current dynamometers, generators, magnetic powder brakes, hydraulic loaders, etc. The gear industry generally uses electric dynamometers, eddy current dynamometers, AC/DC generators, or mechanical loaders, hydraulic loaders, etc., to form mechanical closed-loop feedback test benches and electric closed-loop test benches using generators.

It is advisable to avoid adding extra torque (bending) to the sensor's flexible shaft due to the connection. Therefore, the connection between the sensor and the power and load should be as elastic or flexible as possible. For low power applications, a nylon rope connection is generally recommended, while for high power applications, an elastic pin or high-elasticity coupling is preferred.

Nylon rope connection refers to evenly drilling several holes on the coupling, and using the nylon rope to weave back and forth during installation, finally tying it to fix it. This method is simple and convenient, and the coaxiality requirement during installation is slightly lower. However, it should be noted that the rope holes on the coupling should be chamfered at a large angle and polished with an oilstone, otherwise, it will cause the nylon rope to be cut; there should be a certain gap between the couplings, it is best to have a concave center and separated by ball bearings to avoid mutual collision due to poor coaxiality during rotation; the thickness of the nylon rope can be determined according to the size of the torque, generally φ6～φ12mm can be used; it is best not to use multi-stranded twisted nylon rope, but to use a type of parallel combination of strands plus a sheath.

Absolutely not, especially for small torque sensors. Otherwise, it will cause looseness between the sensor shafts, leading to fluctuating measurement data and unstable zero points.

Yes. However, measures must be taken to prevent bending moments on the sensor's flexible shaft due to transmission turning. For example, a dual bearing support can be used as a turning connection to prevent bending from being transmitted to the sensor's flexible shaft.

The same engine's power output varies under different intake conditions. To establish a standard for measuring engine power output or to allow users to understand the power output of an engine produced under condition A when used under condition B, a national standard was established: to correct the engine power output to "standard ambient intake conditions." This results in a power correction factor, providing a unified standard for comparing engine power outputs. A detailed explanation is as follows:

Intake conditions refer to the ambient atmospheric intake pressure, temperature, and relative humidity at the engine's operating location. When atmospheric pressure is low, atmospheric temperature is high, and relative humidity is high, the amount of dry air inhaled into the cylinder decreases, and engine power decreases; conversely, engine power increases. That is, the performance of the same engine varies greatly under different intake conditions.

Example 1: For a 290 diesel engine, the power output at 14℃ is 13% higher than at 39.5℃, and the fuel consumption rate is 2.6% lower.

Example 2: Under the same temperature and humidity conditions, the actual power output of an engine produced in Datong will be higher at sea or on the plains than in a Datong laboratory, because the altitude is lower and atmospheric pressure is higher at sea or on the plains.

To avoid confusion in power calibration and ensure a unified standard for product quality inspection and comparison, GB1105.1-87, GB/T18297-2001, GB/T21404-2008, and other standards specify standard ambient intake conditions and provide methods for converting power test results under atmospheric intake conditions into corrected power under standard ambient intake conditions.

Standard Ambient Intake Conditions (All Standards)

Atmospheric pressure P0 = 100 kPa (750 mmHg), atmospheric temperature (intake temperature) T0 = 298 K (25℃)

Water vapor partial pressure Psw0 = 1 kPa (7.55 mmHg), dry air pressure Pso = 99 kPa (742.55 mmHg).

Adjustable Fuel Quantity Method Correction Formula (2001 Standard)

When the engine needs to operate under conditions different from the standard baseline conditions, and the power and fuel consumption rate output needs to be adjusted to the standard baseline conditions, please use the following formula:

Peo = Ka × Pe Peo: Corrected power; Pe: Measured power; Ka: Correction factor

geo = β × ge geo: Corrected fuel consumption rate; ge: Measured fuel consumption rate; β: Correction factor

Ka = 1/α

β = α/K

α = K + 0.7 × (K - 1) × (1/ηm - 1)

K = ((Pa - a × Pw) / (100 - a × 1))m × (298 / (ta + 273))n × (298 / (tc + 273))s

Pa: Atmospheric pressure, kPa; Pw: Water vapor partial pressure, kPa; ta: Ambient temperature, ℃;

tc: Inlet temperature of intercooler cooling medium, ℃.

ηm: Mechanical efficiency, if not specified, set to 0.8.

Pw = φ × Psw; φ: Relative humidity; Psw: Saturated water vapor pressure at temperature ta.

The values of a, m, n, and s are defined according to the engine type as shown in the table below:

3. Constant Fuel Quantity Method Correction Formula (2001 and 2008 Standards)

Applicable engines: Reciprocating internal combustion engines (spark-ignition or compression-ignition engines), rotary piston engines (excluding free-piston engines).

This power correction method is used to determine the power measured under test environmental conditions and correct it to the power under standard baseline conditions through calculation.

The test atmospheric conditions should be within the following ranges:

Atmospheric temperature: 15℃~35℃ (spark-ignition); 10℃~40℃ (compression-ignition diesel engine).

Dry air pressure: 90 kPa~110 kPa.

Peo: Power code corrected to standard baseline conditions

Pe: Power code measured under test environmental conditions

2.2.1 For naturally aspirated and supercharged (with and without supercharged intercooling) spark-ignition engines, the power correction factor uses the following formula:

Peo = αa * Pe

αa = (99 / (Pa - Pw))m × ((ta + 273) / 298)n

m = 1.2，n = 0.6

This formula is applicable to carburetor-type or electronically controlled ignition engines (where the air-fuel ratio remains essentially constant under different intake conditions).

The fuel consumption rate of this type is not corrected. If the coefficient αa is outside the range of 0.96~1.06, the actual environmental conditions should be noted.

2.2.2 For compression-ignition diesel engines with pre-adjusted fuel setting values, the power correction factor uses the following formula:

Peo=αc*Pe

geo=β×ge β=1/αc

αc=(fa)fm

fa = (99/( Pa-Pw))m ×( (ta+273)/298) n

Values of m and n

For naturally aspirated or mechanically supercharged engines: m=1.0, n=0.7.

For turbocharged engines without or with air-to-air intercoolers: m=0.7, n=1.2.

For turbocharged engines with air-to-liquid intercoolers: m=0.7, n=0.7. (m=1.0 in the 2001 standard)

fm=0.036*q/r - 1.14

Four-stroke diesel engine: q=(Gf*106)/ (30*n*V)

Two-stroke diesel engine: q=(Gf*106)/ (60*n*V)

Gf: Fuel consumption of the engine.

n: Engine speed.

V: Engine displacement

r: Boost pressure ratio, non-boosted = 1. r=P0/P

P0: Absolute pressure at the compressor outlet of the turbocharger

P: Total intake pressure

When q/r<37.2, fm=0.2; when q/r>65, fm=1.2.

Note: This correction is only applicable for 0.96≤α≤1.06. If it exceeds this range, the actual test environment conditions should be clearly stated in the test report.

For this type of engine, the fuel consumption rate is corrected under full load; the fuel consumption rate under partial load is generally not corrected.

In the 2008 standard, for engine types not included in 2.2.1 and 2.2.2, under actual environmental conditions, if the air density differs from the standard environment by no more than ±2%, the correction factor can be taken as 1; otherwise, the actual environmental conditions should be noted.

For all correction methods, when there is an intake air temperature sensor at the engine intake, the "intake air temperature" should be used to replace the ambient temperature in the calculation.

In Xiangyi software parameters, please name the environmental parameters as "atmospheric temperature, atmospheric humidity, atmospheric pressure" to facilitate the program's calculation of the correction factor.

Saturated water vapor pressure at 0~50℃: