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The cooling system no longer is focused on cooling as much as it is on managing and maintaining a consistent engine and transmission temperature. Since our industry always seems to find a way to inundate us with new acronyms and terminology with every model year, it could be only a matter of time before they start to call it a Powertrain Heat-Management System (PHMS).
Make no mistake: The name is not real – at least not yet. I just made it up. But it’s a very accurate representation of what a modern-day cooling system does. To understand the technology of today’s cooling system and why the name almost deserves a change, let’s first look at a brief history mixed with a touch of science.
The term “cooling system” originally came about on the early automobile, and that’s exactly what they did. However, the early cooling systems were … simple. Scientifically known as “thermosyphon systems,” the hot coolant in the engine rose upward into the top tank of the radiator. As it cooled, it fell to the bottom of the radiator, where it then would flow into the engine block. The result was a continuous circulation of coolant through the engine, requiring no water pump or thermostat to make it work.
Although the early cooling system worked well, it had no choice but to evolve, as engines got bigger and became more powerful. If you think about an engine on a scientific basis, it’s nothing more than a way to convert heat energy into mechanical energy. Basic logic tells us that the more power an engine produces, the more heat is generated that must be removed.
Since cooling systems needed the ability to remove more heat, they quickly evolved into utilizing water pumps and thermostats. Thermostats always have had two purposes. First, the engine coolant must remain in the radiator long enough to transfer its heat to the air. When the thermostat is closed, it allows sufficient time for this to occur, and when it opens, the coolant flows into the engine and is able to absorb heat to begin another cycle.
Second, engines need to operate near the boiling point of water. Why? Because water is a byproduct of combustion, and this high operating temperature ensures that water is evaporated from the engine oil during operation. Without the thermostat set to keep things hot, the engine oil cannot burn off water and will quickly become contaminated.
Cooling systems, even as we entered the era of fuel injection and electronic management, remained fairly simple at first. But we knew that engine temperature was directly related to fuel economy, emissions and power output, and that maintaining that temperature where we wanted it was a necessary step to achieve our goals in those areas.
It didn’t take long before the need for precise engine-temperature control became a prevailing factor affecting both engine and cooling-system design. Many components that we thought would never change began to receive a full dose of technology. Here’s a look at how things are shaping up for the future.
While not an everyday item yet, electrically controlled thermostats are being utilized in some applications, and I expect we’ll see an increase in this. The ability of an internal-combustion engine to achieve maximum fuel economy, minimum emissions and maximum power occurs at slightly different temperatures for different operating conditions. By adding this additional level of precision to temperature control, we can match temperatures to operating conditions, increasing power output and fuel economy.
This need for precise temperature control is why modern fuel-management systems monitor coolant temperature and if there is any deviation outside of the expected norm, a very common diagnostic trouble code (DTC) is P0128 (“Engine Coolant Below Regulating Temperature”). As time goes on, we can only expect this to become a parameter that’s much more closely monitored.
To further illustrate the advantage of an electronically controlled thermostat, consider traditional (old-school) thermostat operation. As the engine warms up, the radiator and hoses remain cold. When monitoring cooling-system performance as a technician, it’s common to keep a hand wrapped around the upper radiator hose. It stays cold until the thermostat opens; then it gets hot really quickly as the coolant flows from the engine into the radiator.
Then we use our hands to feel the radiator tanks warming up, and when they do, we then expect that the electric cooling fans (if equipped) are due to come on within a few moments, and we often move our hand into the path of the air coming off of the cooling fan to sense the volume of airflow and amount of heat being drawn off the radiator. Hi-tech is watching the engine temperature on a scan tool while this happens.
The point of this? The overall process of heat transfer is slow, and extreme precision is not possible with a traditional thermostat. As a result, the most advanced engine-management systems are looking ahead at engine temperature based on throttle position and calculated load, so that they can precisely manage engine cylinder and head temperature, effectively managing combustion efficiency. It’s impressive. Electronics and electronic thermostats make it all possible.
What could possibly change about water pumps? That’s what I used to think, but they are changing. As effective as a traditional belt-drive water pump always has been, if we look at them from an old-school operational standpoint, as we did thermostats, we begin to see the flaws in their operation. Traditional belt-drive water pumps run the whole time at the speed of the engine, but with modern temperature-management technology, it’s not necessary for them to run constantly. Not only does this create an unnecessary drag on the engine, but it also can reduce the accuracy of precise temperature control.
By redesigning the traditional water pump and adding electric water pumps into the system, unnecessary drag is eliminated, and the engine-management system is able to generate coolant flow when needed, as needed. This can help reduce warmup time and also improve overall temperature control.
Electric water pumps also have the advantage of remote locations in engine compartments, which is beneficial as space becomes more and more constricted, and they are utilized for after-run features to help cool components such as turbochargers.
Electric cooling fans are not new by any means, but they no longer are a simple on-or-off type of fan. Early fans often employed a resistor to create both a low- and high-speed option, but many of today’s fans are pulse-modulated variable-speed fans that again give the engine-control module the ability to match fan speed with other operating conditions.
Active Grille Shutters
The newest member of the cooling-system technology family is the active grille shutter. Many manufacturers are utilizing this technology on certain vehicles, which, as you might have guessed, looks just like a set of shutters over some portions of the radiator. This can improve vehicle aerodynamics as well as decrease warmup times. They only open when needed to allow for additional cooling.
Heater cores are part of the cooling system. Even though they don’t generally affect system function in the terms of engine-temperature management, inadequate heat stemming from a restricted heater core is a common complaint. But a restricted heater core is sometimes misdiagnosed as a bad thermostat or vice versa. And some vehicles utilize an electric water pump specifically to move coolant through the heater core. If the pump is bad, it could be misdiagnosed as a restricted heater core. Cooling-system diagnosis always should take into account the ever-increasing complexity of HVAC systems.
Just when you thought there couldn’t be any more, hybrid and electric vehicles are bringing additional changes. Did you ever think you would see a high-temperature radiator and a low-temperature radiator? Plus, a water-cooled air-conditioning condenser? You’ll start to see them on electric vehicles.
You also can throw in some valving and a high-voltage coolant heater to boost heater-core output, plus a completely different cooling circuit for the batteries, power inverter, transaxle and electric motor. The good news for us? There’s a lot more to fix and a lot more parts to sell.
So, when will they start to call it a PHMS? And I’m waiting for the day of GPS-monitored temperature-sensing microchips that float around the cooling system, reporting the exact temperature of the coolant along the way. Sound crazy? Probably. But if it ever happens, just remember where you heard it first.
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link hidden, please login to view consists of four parts: compressor, condenser, expansion valve and evaporator.
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The compressor is the power of the refrigeration cycle and is driven by an electric motor to continuously rotate. It can not only extract the vapor in the evaporator in time, maintain low temperature and low pressure, but also increase the pressure and temperature of the refrigerant vapor through the compression function, creating conditions to transfer the heat of the refrigerant vapor to the external environment medium. In other words, the low-temperature and low-pressure refrigerant vapor is compressed to a high-temperature and high-pressure state, and room temperature air or water is used as a cooling medium to condense the refrigerant vapor.
The function of the compressor is to compress low-pressure steam into high-pressure steam, thereby reducing steam volume and increasing pressure. The compressor sucks the working medium vapor with lower pressure from the evaporator, and sends it to the condenser after the pressure increases. The high-pressure liquid is condensed in the condenser. After being throttled by the throttle valve, it becomes a low-pressure liquid and is sent to the evaporator. In the evaporator, it absorbs heat and evaporates into low-pressure steam, which is then sent to the compressor inlet to complete the refrigeration cycle.
The condenser is a heat exchange device that uses the ambient cooling medium (air or water) to take the heat of the high temperature and high pressure cooling steam from the cooling compressor, so that the high temperature and high pressure refrigerant vapor is cooled and condensed into a high pressure normal temperature refrigerant liquid. It is worth mentioning that in the process of transforming refrigerant vapor into refrigerant liquid, the pressure of the condenser is constant and still at high pressure.
3.Throttle element (namely expansion valve)
The high-pressure and normal-temperature refrigerant liquid is directly sent to the low-temperature scale evaporator. According to the corresponding principle of saturation pressure and saturation temperature, the pressure of the refrigerant liquid is reduced, thereby reducing the temperature of the refrigerant liquid. The high-pressure and normal-temperature refrigerant liquid passes through the throttling element of the decompression device to obtain a low-temperature and low-pressure refrigerant, which is sent to the evaporator to absorb heat and evaporate. In daily life, capillary tubes are often used as throttling elements for refrigerators and air conditioners.
The evaporator is also a heat exchange device. The low-temperature and low-pressure refrigerant liquid evaporates (boils) into steam after being throttled, absorbs the heat of the material to be cooled, reduces the temperature of the material, and achieves the purpose of freezing food. In the air conditioner, the surrounding air is cooled to cool and dehumidify the air. The lower the evaporation temperature of the refrigerant in the evaporator, the lower the temperature of the cooling substance. In the refrigerator, the evaporation temperature of the general refrigerant is adjusted to -26°C to -20°C, and in the air conditioner, it is adjusted to 5°C to -8°C.
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By Sunny Tang
Polishing technology is widely used in precision machining field, It’s very important processing that no matter for precision machined parts or Mold Parts. With the wide application of hardware products, the appearance quality requirements for hardware is becoming more and more higher, then the requirements for surface polishing will also be higher, and the roughness requirements for mirrored and highlighted surface products is especially higher, so the requirements for polishing also becoming higher and higher. Polising Not only increases the beauty of the precision machined parts, but also can improve the Corrosion and wear resistance of the material surface for precision machining parts, it also Convenient to Injection molding processing such as making plastic products easy to demold, reduce the production of injection cycle etc.
A:Rough polishing and grinding: The surface was normally rough after processing of Lathe, Grinding, CNC, cutting or EDM, It need be polished by using oilstone, Use kerosene as the lubricant,the General order of use will be #180 ~ #240 ~ #320 ~ #400 ~ #600 ~ #800~ #1000.
Whetstone polishing is very important and difficult processing, According to the different specifications of processed products like automotive parts, Cross lapping was performed equably at an Angle of about 70 degrees, The optimal round trip range is about 40 ~ 70 mm. Whetstore processing will also be changed according to the material for machined parts, In order to save the time, they will choose #400 to start.
B: Normal Polishing mainly use sandpaper and kerosene.After Whetstone processing will be sanding paper, When sanding paper, pay attention to the round edges, sharp corners, round corners and orange peel appears. so the process of whestone should be done with high precision. The important point for Sanding paper: Sand paper is intersected with hard sticks for grinding like Whetstone processing , and the grinding frequency of one side of sand paper is about 10 ~ 15 times. If the grinding time is too long, the abrasive force of sand paper will be reduced, and then it will lead the surface finish be uneven( This is one of the reason for orange peel appears). sanding paper usually use bamboo piece to grind, Actually the optimal ways is use the wood bar with less elastic or aluminum bar with Low hardness to grind at a 45 degree angle. The grinding surface should not be rubber or highly elastic materials, it can be grind at Acute Angle if the shape can’t grind at 45 degree angle. The Numbers of sandpaper are #220~ #320~ #400 ~#600~ #800 ~#1000~#1200~#1500. In fact #1500 sandpaper is only suitable for hardened die steel (above 52HRC) and not for prehardened steel as this may cause surface burns to the prehardened steel.
C:Precision polishing mainly use diamond paste. If use polishing wheel that mixes diamond abrasive powder or paste to grinding, The paste and polishing wheel can remove the Grinding crack that remained by #1200 and # 1500 sand paper. and then polishing by using felt and diamond paste.It can use the clean polishing chamber in mold processing workshop directly if the polishing precision is Ra0.2, If the polishing precision is very high, then it must use an absolutely clean space to process. It will scrap the polishing surface in high precision if the space has Dust, smoke, dandruff and spittle.
Our Kanou Precision use these polishing technology to service the customer, and also provide kind of solution for customer’s project. We always provide the precision machining part, cnc machined part, CNC turned part, CNC millded part, Mechanical components, automotive spare part to customer, Especially for mass production auto part, these all need this polishing technology, and we received highly praise from customer. We will keep to learn more polishing skills, and bring more advanced polishing tool and meterial to provide more high precision spare parts to customer.
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By OReilly Auto Parts
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