Horse power (Russian designation: l. From .; English:hp ; German: PS ; french: CV ) is an off-system unit of power .
There are several units in the world called “horsepower”. In Russia, as a rule, by horsepower we mean the so-called " metric horsepower " equal to exactly 735.49875 watts .
At present, in Russia formally, horsepower has been decommissioned, but is still used to calculate the transport tax and compulsory motor liability insurance . In Russia and in many other countries, it is still very widespread in an environment where internal combustion engines are used (cars, motorcycles, tractor equipment, scythes and trimmers).
In the International System of Units (SI), the officially stated power unit is watt .
In the English system of measures, the unit of measure of power is considered to be pound-feet per second, but in reality in England it is no longer used, and in the USA it is used extremely rarely.
The International Organization of Legal Metrology (OIML), in its recommendations, refers to metric horsepower as units of measure, "which should be withdrawn from circulation as soon as possible where they are currently used, and which should not be introduced if they are not used" [1 ] .
Content
Horsepower benchmarks
In the Russian Federation, the horsepower value is set equal to 735.499 watts [2] .
In most European countries, horsepower is defined as 75 kgf · m / s , that is, the power that is required to lift a weight of 75 kg vertically at a speed of 1 meter per second with standard gravity acceleration (9.80665 m / s² ) [3] . In this case, 1 liter. with. It is exactly 735.49875 watts , which is sometimes called metric horsepower, although it is not included in the metric system of units .
In the USA and Great Britain in the automotive industry, horsepower is still often equated to 745.69988145 W (designation Eng. hp [4] ), which equals 1.01386967887 metric horsepower.
The USA also uses electric horsepower and boiler horsepower ( Boiler horsepower - used in industry and energy).
Relationships
| Title | Formula | Power in watts |
|---|---|---|
| Metric horsepower | ≡ 75 kgf · m / s | = 735.49875 W (accurate) |
| Mechanical horsepower Indicator horsepower | ≡ 33,000 ft lb f / min ≡ 550 ft lb f / s | = 745.69987158227022 W |
| Electric horsepower | = 746 watts | |
| Boiler horsepower | ≡ 33 475 BTU / h | = 9809.5 W |
To calculate engine power in kilowatts, the ratio of 1 kW = 1.3596 liters should be used. with. (1 hp. = 0.73549875 kW).
History
Around 1789, the Scottish engineer and inventor James Watt coined the term “horsepower” to show how many horses could be replaced by steam engines . In particular, it is alleged that one of the first machines Watt bought a brewer to replace it with a horse that powered a water pump [5] . According to a common legend, the brewer decided to cheat, choosing the strongest horse and forcing it to work to the limit. Watt accepted and even exceeded the figure received by the brewer, and it was the power of the constructed machine that became the standard, despite the fact that the real power that the horse develops during normal operation for a long time is much less - by some estimates, one and a half times. [6] [7]
At that time in England barrels from 140.9 to 190.9 liters were used to lift coal, water and people from mines. There was (and is) a barrel volume unit based on the weight of a typical barrel with a weight that weighed 380 pounds ( 1 pound = 0.4536 kg ), i.e. 1 barrel = 172.4 kg.
Naturally, only two horses could pull such a barrel by the rope thrown over the block. The force of an average workhorse during 8 hours of work is 15% of its weight or 75 kgf with a horse weight of 500 kg . For 8 hours, a horse with such effort can go 28.8 km at a speed of 3.6 km / h ( 1 m / s ).
Observing a traditional source of energy - a horse, Watt came to the conclusion that two horses at a speed of 2 nautical miles / h (approximately 3.6 km / h ) can pull a 180 kg barrel. In this case, the horsepower in English measures takes the form of 1 liter. with. = 1/2 barrel · 2 nautical miles / h = 1 barrel · nautical mile / h (here the barrel is taken as a unit of force , not mass ). The same in smaller units is 380 pounds at 98.4 ft / min, which is approximately equal to 846.4 watts. If you round off the calculations in pound-feet per minute (leaving the acceleration of gravity in SI units equal to 9.82093 m / s 2 , which approximately corresponds to the latitude of St. Petersburg and about 0.01 m / s 2 lower than at the pole [ 8] , then 1 watt = 433.9735 lb-ft / min) and take the load that the horse must pull at a constant speed of 1 m / s equal to 75 kg, then the horsepower will be 736.56 watts, which is approximately 320,000 lb-ft per minute. Therefore, 1 horsepower is considered equal to 735.5 watts [8] .
Watt's calculations related to horse power averaged over a long time. For a short time, a horse can develop a power of about 1000 kgf · m / s, which corresponds to 9.8 kW or 33,475 BTU / h (boiler horsepower). According to other sources - up to 15 liters. with. at the peak.
At the Second Congress of the British Science Association in 1882, a new power unit was adopted - watt (designation: W, W), named after James Watt (Watt), creator of the universal steam engine. Prior to this, most calculations used horsepower introduced by James Watt.
Engine power
For the power of automobile engines, there are not only different units of measurement, but also different measurement methods that give different results. The standard power measurement method adopted in Europe uses kilowatts. If power is given in horsepower, then the measurement methods in different countries may differ (even if the same horsepower is used).
The United States and Japan use their own standards for determining engine horsepower, but they have long been almost completely unified with others. In both America and Japan, there are two types of indicators:
Net Measurement
Net engine power measurement ( ital. Netto - clean , net ). It provides a bench test of an engine equipped with all auxiliary units necessary for the operation of the vehicle: generator, silencer, fan, etc.
Gross Measurement
It includes a bench test of an engine that is not equipped with additional units necessary for the operation of the vehicle: a generator, a cooling system pump, and so on. Gross power is higher than net power by 10–20% or more than before the establishment of the federal standard in 1972, North American car manufacturers were widely used, overstating engine power.
DIN measurement
The power measurement method of the German Institute for Standardization (Deutsche Industrie Normen, DIN) involves a bench test of an engine with "inseparable" equipment, which is necessarily present on the car. Inseparable equipment in this method is a cooling fan, a cooling pump, oil and fuel pumps, and also a generator that does not have a load. Tests are conducted without an air filter and silencer.
ECE Measurement
Horsepower in transport taxation
Russia
In Russia, the value of the transport tax depends on the engine power in horsepower. Conversion to horsepower is done by multiplying the engine power, expressed in kW, by a factor of 1.35962 (that is, a conversion factor of 1 hp = (1 / 1.35962) kW is used). Although the issue is not settled by law, the tax authorities advise rounding to the second decimal place [9] in such a conversion to off-system units of power (hp).
Each region has the right to increase or decrease the size of tax within the limits of federal norms.
If the power is less than 100 liters. With., then, for example, in the Moscow region paid 7 rubles / liter. with. per year, and if a little more - already 29 rubles / liter. with. in year. Moreover, from 101 liters. with. up to 150 liters with. tax rate is the same. Thus, due to different power values, the price changes from less than 700 to several thousand rubles per year. This fact leads to annoying oddities. So, the power of the South Korean car Hyundai Accent is exactly 75 kW, that is 102 liters. with. For the American car owner, an even more offensive figure would be 100.7 hp, but in the USA the tax does not depend on horsepower. In the USA, some taxes (road, environmental) are included in the price of gasoline , in addition, annually you have to pay personal property tax (personal property tax), directly proportional to the price of the car.
Other countries
In the past, in some countries (for example, the UK, Germany, Belgium, France, Spain), the transport tax depended on horsepower. In some countries, they refused to use power for tax purposes (for example, in the United Kingdom in the forties they began to use the size of a car), in others (for example, in France), instead of horsepower, kilowatts were used. From those times the expressions “Caballo fiscal” and “Cheval fiscal” remained.
In addition to the use of horsepower in the calculation of transport tax, in the Russian Federation this type of power unit is also used in insurance. Namely, when calculating the insurance premium for compulsory third party liability insurance of vehicle owners (colloquially - “auto citizen”).
Designation on machines
For passenger cars, the designation of power on the body is an extremely rare phenomenon, but it is more common on trucks and tractors. On European-type trucks, including some Russian ones, the horsepower is indicated on the cab either above the wheel axle of the front axle or on the front of the cab.
On electric generators, the power of the internal combustion engine is indicated by the Latin letters HP, for example, 5HP. The electric power of the generator, as a rule, is noticeably less.
Truck Scania P320 with a capacity of 320 liters. with.
Volvo FH 12 car, on the cab a little further from the door, the Euro 5 environmental class and a capacity of 480 liters are indicated. with.
See also
- Nominal power
- Kilowatt
- Tax horsepower
- Engine capacity
- Engine configuration
Notes
- ↑ OIML International Document D2. Legalized (officially approved for use) units. Appendix B (inaccessible link) . Date of treatment November 30, 2014. Archived on October 14, 2013.
- ↑ GOST 8.417-2002. State system for ensuring uniformity of measurements. Units of quantities. Appendix B. Archived November 10, 2012 on the Wayback Machine
- ↑ Horse power // Small Encyclopedic Dictionary of Brockhaus and Efron : in 4 volumes - St. Petersburg. 1907-1909.
- ↑ Entertaining hippology . Magazine "Autopilot". Date of treatment January 17, 2009. Archived August 23, 2011.
- ↑ Engines and propulsors . The journal "Science and Technology". Date of treatment June 8, 2009. Archived August 23, 2011.
- ↑ Yakov Isidorovich Perelman , Physics at every turn
- ↑ Popular Mechanics . September 1912, page 394
- ↑ 1 2 Enokhovich, A.S. Handbook of physics and technology. - 3rd ed., Revised. and additional .. - Moscow, 1989. - S. 45, 61. - 224 p. - ISBN 5-09-000622-9 .
- ↑ Semenikhina V.V. Transport tax. Commentary on Chapter 28 of the Tax Code of the Russian Federation. Moscow 2006, p.35