Technology that secretly protects your wallet and quietly helps save fuel

I believe everyone has to think about the question "Which one is rising faster, oil prices or house prices?", but there is no doubt that these two price increases have made our wallets "thinner". So I believe everyone is paying special attention to information about how to drive to save fuel and what technology can save fuel. In the future, new energy vehicles will definitely be popular. Is there no way to save fuel at this stage except buying new energy vehicles? The answer is of course no. This time, let's take a look at those fuel-saving technologies that are easily overlooked by us.

When it comes to energy-saving technologies, "engine direct injection", "dual-clutch transmission", "turbocharging" and "mechanical supercharging" will pop into everyone's mind. Since everyone is too familiar with them, this article will not let them "appear" again. If you are interested in them, you are welcome to click on the relevant links at the end of this article.

■ Lightweight

Fuel saving index: ★★★☆

"If you don't have some carbon fiber on your body, you'd be embarrassed to say hello to others."

When it comes to the concept of lightweight, people often think of modification and control first. In fact, for ordinary cars, lightweighting is the most direct way to save fuel, and it is already one of the important goals of all manufacturers in developing models. Supercars would be embarrassed to say hello to others if they don’t use some carbon fiber on their "body". Of course, the goals that supercars and family cars want to achieve through lightweighting are not exactly the same.

Lightweighting is a systematic and complex project. Lightweighting of materials is not the only goal, and structural strength is also an important factor to consider. The materials include lightweighting of body-in-white materials and component materials. The seemingly simple body-in-white is actually an important goal of "weight loss". It is not an exaggeration to say that all-aluminum body, carbon fiber cover, aluminum doors, aluminum anti-collision beams, and die-cast aluminum alloy tower tops are all weight loss products. The fact that a large amount of aluminum alloy is used in parts such as the gearbox housing, differential housing, engine cylinder block and cylinder head adds to the "weight loss" effect.

Composite materials will be king in the future. Mercedes-Benz's strategy in this regard is to "use multiple materials together". In the past, cars used to have all-steel bodies, but now they use high-tech steel. In the future, different types of high-tech steel will be used in conjunction with aluminum materials. Aluminum materials will be more widely used in the near future, and will be used in combination with different lightweight materials such as industrial plastics and carbon fiber to achieve lightweight requirements.

But behind high technology there is always a "shadow" of cost control, and the current solution is to "use materials according to their characteristics". For example, the cockpit must use high-strength steel to withstand sufficient impact and absorb energy; some places that do not require high-strength steel use magnesium alloy; and the fenders and doors can use lightweight aluminum to achieve lightweight requirements.

"Although the wheelbase of the new Audi A3 will be longer, its weight will be reduced."

Don’t think that lightweight technology is only for supercars and luxury cars. In fact, many “small guys” are also following suit. The new generation Audi A3 is an example. Although the wheelbase is longer than the old model, the new generation Audi A3 weighs only 1.1 tons, which is nearly 2 adults lighter than the old A3.

At the same time, we must also make it clear that lightweighting is not simply replacing iron with aluminum. The two key words "high strength" and "lightweight" are not contradictory. Any lightweighting should be completed while ensuring the strength of the vehicle body. High-strength body structure is just basic homework. Using materials and structural design to reduce redundant weight while ensuring strength is the most important thing in this era of "high efficiency and low energy consumption". Lightweighting is not a matter of simplifying the body structure with a hammer or chisel. The load-bearing structure uses higher-strength materials and less materials than before, but can achieve the same strength. Taking the fender as an example, the force of the fender is analyzed and gradually optimized, that is, the excess parts are removed bit by bit, and the remaining structure is the most streamlined and optimal result without affecting the strength.

■ Aerodynamics

Fuel saving index: ★★★☆

I believe you must have had this experience when riding a bicycle: when it is windy, if you still ride in the usual sitting position, you have to use all your strength to pedal to be as fast as the person walking next to you. At this time, lying down seems to save a lot of effort.

The same is true for cars. A large part of the power is consumed by the fuel used to drive the machine, and when the car is running at high speed, part of it is to overcome the air resistance. In fact, a long time ago, when people began to desire to drive at a higher speed, they found that high-power output power units alone could not reach the dream horizon, so some people began to study aerodynamics. They found that in order to obtain favorable driving conditions, they had to break the traditional pattern in the body shape and let the original square body evolve into a rounded shape.

Of course, aerodynamics is far from being as simple as changing a car body from a square box to a round soap. What kind of shape has the lowest air resistance, how to reduce turbulence formation, and a series of other issues are all within the scope of aerodynamic research. Another thing worth noting is that in our impression, hatchbacks are mostly short and compact, and it seems that they have less air resistance than those "stupid" three-box cars. In fact, this is not the case. Since the rear area of ​​a hatchback is large, the vacuum area formed by the rear is large, and the negative pressure generated is large, resulting in a greater pressure difference between the front and rear, and the air resistance of the vehicle is correspondingly higher.

Look, the truth is not always what we think, but nothing is absolute. The "exception" here is the new B-Class of Mercedes-Benz. At the price level of the old B-Class in China, the lowest drag coefficient of mass-produced cars is only 0.27 - from the Regal and Ruiyi (both are three-box mid-size sedans). As a two-box model, it is really surprising that it can come up with a drag coefficient of only 0.26. It is no exaggeration to say that among the compact models of mass production, the new B-Class has an absolute leading advantage in aerodynamics. Even the three-box sedans of the same level mostly have a drag coefficient of around 0.3. Mercedes-Benz engineers have done a lot of optimization work on the aerodynamic design of the B-Class. In addition to the exterior contour, they have also done a lot of experiments and improvements on the smoothness of the airflow under the car. The serrated wheel arch spoiler at the front end of the front wheel is one of the results. It is reported that Mercedes-Benz will also provide an "ECO" optional kit in the future. After installing this kit, the drag coefficient of the Mercedes-Benz B can be reduced to 0.24!

When the design of the body exterior may have encountered a bottleneck in creating a low drag coefficient, in order to pursue perfection, the designer intends to jump out of the body design field and turn his attention to technology. In the new generation Audi A8, the space between the air intake grille and the water tank is sealed, so that the incoming air can enter the cooling system without loss and achieve the maximum heat dissipation effect, increasing the efficiency of air flow. The design of the scales on the surface of the radiator and the electronic cooling fan blades has also been optimized accordingly. After such a careful layout design, the lowest wind resistance effect can be achieved.

Don't think that aerodynamics is just a "surface study". In fact, the aerodynamics of the chassis are also important. In our chassis disassembly column, you can see that many cars have aerodynamic designs on their chassis. Good aerodynamic design of the chassis can help the vehicle reduce the air resistance generated by the chassis, wheel arches and wheel hubs. Covering the chassis with a complete guard plate can make the air flow through the chassis faster, and the design of the guide groove helps guide the airflow through the chassis more reasonably.

■ Intelligent variable grille

Fuel saving index: ★★★

We all know that the normal operating temperature of modern engines is relatively high, generally between 100 and 110 degrees Celsius. In the cold state, especially in winter, quickly raising the temperature and reducing the idling time is one of the tips for saving fuel. This system is installed in front of the radiator, and the computer controls the time and angle of its opening and closing, which can control the air flow to the radiator and the engine compartment. Achieve the purpose of quickly raising or lowering the temperature. At the same time, another function of the intelligent variable grille is to further enhance its advantage in aerodynamic performance. Take the new Focus as an example. Under the joint effect of aerodynamic body design, the wind resistance is reduced by 7.8%, and the wind resistance coefficient is only 0.295.

In the cold state, by closing the grille, the engine's operating temperature can be raised as soon as possible, so that the vehicle's OBD system enters the closed-loop working state earlier, thereby reducing emissions. At the same time, with the electronic thermostat, the engine's thermal management system can be more accurately regulated.

This system is not unique to the Focus. Models such as the BMW 5 Series and Buick Regal LaCrosse eAssist are also equipped with similar intelligent grille closing technology.

■ Variable displacement air conditioning system

Fuel saving index: ★★★

The compressor used in the variable displacement air conditioning system can automatically adjust the displacement during operation according to the changes in signals such as speed, suction and exhaust pressure, as well as the vehicle's operating conditions and external environmental conditions, to achieve energy saving, noise reduction and optimal control of the cabin environment. Most passenger car air conditioning systems are non-independent, and their compressors are directly driven by the engine through a pulley. When the car is driving at high speed, the input cooling capacity increases with the increase in engine speed. The increase in the car's cooling capacity not only wastes some power, but also affects the car's driving performance. At this time, the variable displacement air conditioner will automatically adjust the working displacement, reduce the cooling capacity, and reduce power loss.

"POLO uses a variable displacement air conditioning system"

■ Water pump can be turned off

Fuel saving index: ★★★

As we all know, the temperature of the engine directly determines its working state. When the temperature exceeds the limit that the engine can withstand, it will bring disastrous consequences. If the temperature is too low, the efficiency of the engine will be very low. The engine cooling system is a crucial link. In order to create a "comfortable" working environment for the engine, engineers have made unremitting efforts. Modern engines generally use water cooling, but during cold start, the engine temperature rises relatively slowly. Is there no way to solve the fuel consumption problem caused by the "warm-up" time? The answer is of course no. The technology of shutting off the water pump solves this part of the problem.

The water pump can be turned off, which means that the vanes can be connected or disconnected with the pulley through an electronically controlled connecting shaft valve. Under cold start conditions, the variable water pump vanes stop rotating, suspending the engine coolant circulation. Under cold start conditions, the engine cylinder head heats up almost twice as fast as that without a thermal management system, greatly shortening the warm-up time and reducing fuel consumption. After the engine heats up, the thermal management system will heat the transmission oil through a heat exchanger, allowing the transmission system to reach the optimal operating temperature faster.

■ Variable displacement oil pump

Fuel saving index: ★★★

If a car is compared to a person, then the engine must be the heart, and one of the guarantees for the smooth beating of this "heart" is the lubrication system. When the engine is working, the lubrication system must continuously deliver sufficient clean oil at appropriate temperature to the friction surfaces of all transmission parts, and form an oil film between the friction surfaces to achieve liquid friction, thereby reducing frictional resistance, reducing power consumption, and alleviating machine wear. The oil pump is the top priority.

The oil output of a general non-variable displacement oil pump increases with the increase of engine speed, and the two are in a linear relationship. Simply put, the harder the engine works, the more "prizes" it gives to the engine. In order to ensure the minimum oil output at low speed and the minimum oil pressure at high speed, the oil pump will be designed to be very large, which puts higher requirements on the layout of the engine compartment. At the same time, when the engine is at high speed, excess lubricating oil will return from the oil circuit, resulting in increased engine power consumption. The variable displacement oil pump will adjust the oil pressure and oil volume according to the engine conditions, thereby achieving the purpose of saving fuel.

■ Intelligent disconnection of generator

Fuel saving index: ★★★

The working principle of this technology is that when the vehicle is driving normally or accelerating suddenly, there is no need to generate electricity. At this time, the generator is disconnected to reduce energy consumption. When the vehicle is coasting or decelerating, in order to ensure the use of electricity, the generator is connected and charges the battery. It can be said that the work done by the smart disconnection motor is like a hydroelectric power station, discharging flood water to generate electricity during peak hours and storing flood water and electricity during low hours.

■ Electric power assist

Fuel saving index: ★★★★

We are all familiar with power steering. Without its assistance, I believe our drivers would be strong men with well-developed biceps, and driving would become a physical job. Power steering makes driving simpler and easier, and makes the vehicle more responsive, which improves safety to a certain extent.

Common power assists are divided into hydraulic power assist and electric power assist. Hydraulic power assist is further divided into mechanical hydraulic power assist and electronic hydraulic power assist. Since the hydraulic pump of mechanical hydraulic power assist is driven by the engine belt, it will consume part of the engine power, which will also affect the fuel economy and the power of the vehicle, especially for small-displacement models with relatively weak power. The electronic hydraulic power assist electronic pump needs to be driven by the power of the generator.

The electric power steering changes the power steering mechanism from a complex hydraulic mechanism to a system that relies on an electric motor to generate power. The structure of the electric power steering system is very simple. It does not have a hydraulic pump, a fluid storage tank, a hydraulic pipeline, or a steering column valve body structure. Instead, it is composed of a sensor, a control unit, and a power steering motor. The power steering motor is driven by a 12V power supply system, which is commonly known as a battery. Not "borrowing power" from the engine indirectly saves fuel consumption, which is the secret of electric power steering to save fuel.

■ Low rolling resistance tires

Fuel saving index: ★★★★

As mentioned above, a large part of the vehicle's fuel is consumed when driving the machine. When the car is running at high speed, part of it is consumed to overcome the air resistance, and the other part is consumed to deal with the friction and rolling resistance between the tires and the road surface.

"The picture shows the Golf Blue Drive model using Hankook's low rolling resistance tires."

"The picture shows the Goodyear low rolling resistance tires used by Volt."

Many new energy vehicles or fuel-saving models are now equipped with low rolling resistance tires. The secret of low rolling resistance lies in the additives used in tire manufacturing. Take Goodyear's XT tires as an example. A certain proportion of silicon materials and a full carbon black formula are added to the tread rubber formula. Because of the high adsorption performance of silicon, good thermal stability, stable chemical properties, and high mechanical strength, silicone tires are more wear-resistant and anti-aging than ordinary tires, so that XT tires can effectively reduce rolling resistance and save fuel consumption.

■ Engine start-stop technology

Fuel saving index: ★★★★

Stop-and-go driving is very common on urban roads, and fuel consumption increases during stop-and-go driving or idling. The engine start-stop technology is designed to solve the problem of frequent short-term stops on urban roads and reduce idling fuel consumption.

"The picture shows the start-stop button on smart"

When the vehicle stops due to congestion or traffic lights at an intersection, the driver presses the brake pedal to stop the car and shift gears. At this time, the Start/Stop system automatically detects: the engine is idling and not in gear; the battery sensor shows that there is enough energy for the next start. When the conditions are met, the engine automatically stops. To start again, just release the brake or turn the steering wheel.

Now more and more car models are equipped with the start-stop function. Although the names are different, the effects are similar. From smart to Audi A6L, the "size" is not important. What remains is the contribution to fuel saving and environmental protection.

"Start-stop is no longer a "luxury configuration", and it is available on all levels of vehicles"

■ Braking energy recovery

Fuel saving index: ★★★

Whether it is congested urban traffic or flat highways, when the vehicle is coasting and braking, part of the kinetic energy can be converted into electrical energy and stored in the battery through the generator. Although it is much "weaker" than hybrid models in braking energy recovery, the accumulation of these subtle energy-saving measures will eventually significantly improve the fuel economy of the entire vehicle.

Let's take the Audi A3 e-tron as an example. When the comfort mode is selected, the degree of energy recovery is reduced, the sense of frustration is reduced, and the driver and passengers' feelings are more emphasized; when the power saving mode is selected, the system increases the degree of energy recovery to achieve the maximum range. But no matter which mode is selected, the system will charge the lithium battery with the collected energy during coasting and braking.

■ Variable cylinder

Fuel saving index: ★★★☆

When it comes to variable cylinder technology, the first thing that comes to our mind may be Volkswagen or Audi. In fact, variable cylinder or variable displacement technology was first proposed by General Motors in the 1980s, but due to the immaturity of the technology, it was shelved over time. Until 2001, it amazed everyone with the Cien concept car. We are more familiar with the story after that. General Motors applied variable displacement technology to the Escalade. At the same time, Mercedes-Benz is also studying similar technologies. Chrysler has applied the multi-stage variable displacement control system (MDS) to the Hemi engine, while Honda's VCM, Volkswagen ACT, and Audi's cylinder on-demand operation system are all junior.

GM Active Fuel Management

Active Fuel Management, also known as Displacement on Demand, abbreviated as AFM or DOD, was first used in the GM Cadillac L62 engine in 1981. It also relies on shutting down some cylinders and stopping them from working under low load conditions according to the engine operating conditions, thereby achieving the purpose of improving fuel economy and reducing exhaust emissions. However, due to the immature technology at the time, active fuel management technology was shelved over time. It was not until the debut of the Cien concept car in 2001 that it returned to our sight. Later, it became more well-known along with the Escalade as the SUV wave swept the world.

"The 2001 Cadillac Cien concept car marked the beginning of the return of active fuel management technology to the public eye."

"Active fuel management technology has become familiar to the public along with the Escalade"

Active fuel management technology controls the oil supply of hydraulic valve lifters through solenoid valves. By adjusting the oil pressure of the valve lifters of selected cylinders, some cylinder valves remain closed. These cylinders will stop taking in or exhausting air, and the selected cylinders will not participate in the engine power output, thereby achieving the purpose of improving fuel economy.

Mercedes-Benz cylinder automatic closing technology

Automatic cylinder shutdown technology is not new to Mercedes-Benz. As early as 1998, the eighth-generation Mercedes-Benz S-Class, numbered W220, was equipped with this technology.

"The picture shows the Mercedes-Benz S500"

The automatic cylinder shut-off technology can shut down unused cylinders when needed, thus significantly reducing fuel consumption. At the same time, the cylinder shut-off technology will not affect the smooth operation, torque output and quietness of the engine. When the engine is working under partial load, the S500's 8-cylinder engine can temporarily shut down four of its cylinders, thereby reducing the vehicle's average fuel consumption by about 7%, achieving greater fuel economy.

Chrysler Multi-Displacement System

Chrysler and Mercedes-Benz

In fact, when it comes to the origin of MDS, there is a short story related to Mercedes-Benz. At that time, Daimler-Chrysler took the lead in launching the 5.8L V12 engine equipped with ACC (Active Cylinder Control) technology in 2001 and applied it to the Mercedes-Benz CL600 and S600. However, this engine was discontinued just one year later and faded out of people's sight. Later, Chrysler also planned to develop corresponding technology for its own engine. They found Eberspaecher, which had participated in the ACC project, but this time it was Eberspaecher's North American center - Eberspaecher North America, who participated in the development. Together, they tailored the MDS-Multi-Displacement System multi-stage variable displacement control system for Chrysler's Hemi engine.

"The 2005 third-generation Grand Cherokee was one of the first models to use the Hemi engine with MDS technology."

MDS is a multi-stage variable displacement control system tailor-made for Chrysler's Hemi engine. Since the Hemi engine adopts an OHV structure and the camshaft is covered with cams, it is impossible to design a more complex auxiliary rocker arm and hydraulically controlled connection mechanism like Honda's VCM engine, so the only solution can be found on the original structure.

『Camshaft and valve tappet mechanism of Hemi engine』

The final solution is to make a fuss on the tappet that contacts the cam. They designed a unique slider structure for the tappet of the hemi engine. The slider is connected to the valve push rod. There is a positioning pin under the slider. The pin can make the slider and the tappet become one, push the valve push rod, or make the slider move, so that the tappet cannot push the valve push rod. Engineers designed a unique oil channel for the pin in the engine, relying on the lubricating oil in the lubrication system to provide hydraulic pressure to push the pin (solenoid valve control). The pin itself has a return spring, which can automatically return to its position when the hydraulic pressure disappears. When the engine is running normally, the pin will block the slider so that it cannot move up and down freely. The tappet directly pushes the push rod to drive the valve rocker arm. When the engine needs to close the cylinder, the pin is released, and the slider can slide up and down. When the tappet moves up and down, the slider and the tappet move relative to each other and no longer push the push rod. In this way, the valve is closed, and the ECU stops spraying oil to the cylinder, achieving the effect of "closing the cylinder" and realizing "variable displacement".

"The valve is controlled by a specially designed tappet, and a hydraulically controlled pin prevents the tappet from pushing the valve pushrod."

"The old Chrysler 300C engine also uses MDS technology."

Honda Variable Cylinder Management

The VCM shuts down the intake and exhaust valves through the VTEC system to stop the operation of specific cylinders, and at the same time, the powertrain control module cuts off the fuel supply to these cylinders. In any situation that requires high power output, such as starting, accelerating or climbing a hill, the engine will put all 6 cylinders into operation. In medium-speed cruising and low engine load conditions, the system will only operate one cylinder group, that is, three cylinders. During medium acceleration, high-speed cruising and gentle slope driving, the engine will operate with 4 cylinders.

In the 3-cylinder working mode, the rear cylinder group is stopped. In the 4-cylinder working mode, the left and middle cylinders of the front cylinder group work normally, and the right and middle cylinders of the rear cylinder group work normally.

"The VCM technology is also used in the Civic, which has an unacceptable appearance."

What is special is that the spark plugs in the non-working cylinders continue to fire to minimize spark plug temperature loss and prevent spark plug oil contamination due to incomplete combustion when the cylinder is put back into operation. The system is electronically controlled and uses special one-piece slide valves, which play a dual role as the rocker shaft bracket in the cylinder head. Based on the instructions issued by the system electronic control unit, the slide valve selectively directs oil pressure to the rocker arm of a specific cylinder. This oil pressure then pushes the synchronization piston to connect and disconnect the rocker arm.

Volkswagen ACT Active Cylinder Management System

At this year's Geneva Motor Show, the blue little guy at the Volkswagen booth, the POLO BlueGT, really attracted people's attention, not only because it was dressed in blue, but also because it used a 1.4T turbocharged engine code-named EA211, which was newly developed based on Volkswagen's transverse modular MQB platform, and was equipped with an ACT active cylinder management system. The ACT active cylinder management system shuts down two cylinders under certain conditions and only uses the other two cylinders to run, so as to achieve the effect of saving fuel.

This 1.4T engine with cylinder deactivation technology is a good reference to Audi's AVS variable valve lift technology. Simply put, this AVS system changes the valve lift and timing under different working conditions by switching two cams with different angles. The cylinder deactivation system only needs to replace the high-angle cam in the AVS system with a cam without lift, and this cylinder deactivation technology has been applied to the Audi V8 4.0TFSI.

Volkswagen has determined the optimal moment to shut down the cylinders based on a survey of road conditions in many countries, which is to start the cylinder shut-down system when the engine speed is 1250-4000rpm and the torque is 25-100N·m. When the driver steps on the accelerator pedal, the two shut-down cylinders will quickly resume work within 13-36 milliseconds. The system can intelligently detect the traffic environment and congestion of the vehicle and intelligently disable the cylinder shut-down function. The driver can know whether the car is currently running with two cylinders or four cylinders from the multi-function display on the dashboard.

Audi cylinder on demand system

When talking about Volkswagen's ACT active cylinder management system, it was mentioned that its key point is to borrow Audi's AVS variable valve lift technology. Now let's talk about Audi's cylinder on-demand operation system. Audi's 4.0-liter V8 twin-turbocharged engine is equipped with this technology.

Cylinder on demand operation is not complicated to implement. It can be achieved by upgrading the original AVS system, that is, by installing a set of zero-stroke cams on the camshafts on both sides of the intake and exhaust. In other words, when the AVS actuator switches the cam to zero stroke, the camshafts on both sides of the intake and exhaust cannot drive the valves to complete the intake and exhaust actions. At the same time, the injection system stops supplying fuel to the corresponding cylinders, and the ignition system will also stop working.

Summary of the full text:

I believe that after reading this, you must have understood the truth that "saving fuel is not just about changing the engine". As the saying goes, many hands make light work, and the fuel saving effect we see is the result of the concerted efforts of all parts. As the old saying goes, no matter how many advanced technologies there are, they are not as good as the correct driving method. If you often floor the gas and don't see any car faster than you, I believe that such a driving method will not achieve the fuel saving effect no matter how many technologies you have.