Interpretation of Honda CR-V hybrid technology

I believe that many of my friends' screens have been flooded with the new CR-V in the recent period. "Global cumulative sales of over 1.5 million units", "Guide price 169,800-259,800 yuan", "IIHS highest safety rating", "Original compact SUV", "How to increase the price/how much to increase" and other labels were quickly attached to this popular SUV. But compared with the gasoline version, the hybrid version is Honda's "killer weapon" this time. However, how many articles can thoroughly interpret the new CR-V Hybrid? Today, I will take advantage of the opportunity to present a simple and unpretentious technical article that is very different from those glamorous XX outside. From the perspective of the powertrain, I will briefly analyze its hybrid "black" technology to see if it lives up to everyone's high expectations.

The new generation CR-V Hybrid is equipped with Honda's i-MMD dual-motor hybrid system used in mid-size cars. So here comes the question (pay attention!): (What) What is this i-MMD system/what is special about it? (Why) Why is it different from Toyota's THS-II hybrid system? (How) How does it work? Let me take you to explore its true face with pictures and texts.

What——What is this i-MMD set/is there anything special about it?

Speaking of Honda's i-MMD, we have to talk about its brothers and sisters i-DCD and SH-AWD. At the end of 2012, Honda Motor Co., Ltd. released three hybrid systems for large, medium and small vehicles at once, namely:

1. The SPORT HYBRID i-DCD (Intelligent Dual Clutch Drive) system with a single motor structure for small cars, which is installed on the Japanese version of the Fit Hybrid, etc.

2. The dual-motor SPORT HYBRID i-MMD (Intelligent Multi Mode Drive) system for mid-sized cars, which is installed on the Honda Accord Hybrid and Honda CR-V Hybrid.

3. The three-motor SPORT HYBRID SH-AWD (Sports Hybrid-Super Handling-All Wheel Drive) system for large and high-performance vehicles, such as the new generation Acura NSX.

What? Are you confused after reading the above three points? Perhaps this is Honda's consistent style - no matter how complex the technology itself is, the name must be complex enough. The names of these three systems have been forcibly "Honda-ized".

How——How does it work?

Let's get back to the point. Today we are going to talk about the i-MMD hybrid system on the CR-V Hybrid, which consists of a 2.0L Atkinson cycle dual overhead camshaft gasoline engine, a high-power generator, a drive motor, an e-CVT electric continuously variable transmission, a PCU (Power Control Unit) and a lithium battery pack. It is worth mentioning that the maximum power of the engine on the CR-V Hybrid is 107kW, the maximum power of the electric motor is 135kW, and the total power of the entire i-MMD hybrid system can reach 158kW. Under different vehicle conditions, it has three driving modes, and the principles are as follows:

1. EV Drive Mode, also known as pure electric drive mode. In this operating mode, the CR-V Hybrid is almost the same as an ordinary pure electric vehicle: the engine does not work, and the lithium battery pack directly drives the vehicle through the drive motor. In this driving mode, the energy generated by vehicle braking will be recovered and recharged into the lithium battery pack.

2. Hybrid Drive Mode. In this operating mode, the operating mode is roughly equivalent to that of an extended-range electric vehicle: the engine is started, but the power separation device is disconnected, and the engine speed is maintained in the most economical speed range, driving the generator in the e-CVT electric continuously variable transmission to generate electricity, which is charged through the PCU to the lithium battery pack located at the rear of the vehicle. The electric energy is provided to the drive motor through the lithium battery pack to drive the vehicle forward. When the vehicle brakes, the engine equipped with a start-stop device will be controlled by the start-stop device and stop operating to save fuel. At the same time, the brake energy recovery system still works and can provide additional energy to the battery pack. When the vehicle needs to accelerate sharply, the lithium battery pack can provide additional electricity to allow the electric motor to instantly generate maximum torque output.

3. Engine Drive Mode. In this mode, the operation mode is actually similar to the models that have been on sale for a long time and use Honda's IMA hybrid system: the engine starts, and at the same time, the power separation device is normally connected, the engine speed is controlled by the driver's throttle depth, and the mechanical energy is directly transmitted to the wheels through the e-CVT electric continuously variable transmission. In order to provide greater power during acceleration, the battery pack is also in standby mode, and can provide power to the motor when needed, allowing the motor and engine to work together.

It is worth mentioning that the e-CVT electric continuously variable transmission mentioned above does not actually exist. In other words, i-MMD does not have a transmission in the strict sense. Because when it is driven by the motor, it uses one gear ratio, and when it is driven by the engine, it uses another gear ratio, and the two gear ratios are relatively fixed. At medium and low speeds, the drive is all done by the motor, and a single transmission ratio is sufficient. For the engine, only one high-speed small gear ratio is provided (equivalent to no conventional first, second, third, and fourth gears, but only one highest gear) to cope with high-speed driving conditions. At this time, if the engine torque is insufficient due to the reduction in speed, the system will automatically let the motor follow up, which invisibly realizes the seamless connection of power from low speed to high speed in various ranges, achieving the effect of "e-CVT".

Why——What makes it different from Toyota's THS-II hybrid system?

As two Japanese giants, Honda's hybrid system must be compared with Toyota's THS-II system. From the structure of the i-MMD system just introduced, except for the unique DOHC i-VTEC technology, there seems to be no big difference between the two. However, i-MMD has three driving modes. The system can automatically cut off or restore the connection between the engine and the motor according to the driving conditions, and always maintain economical and efficient operation. In order to better distinguish them, the following are two cases for you:

Taking the hybrid drive mode as an example, the engine and the motor are output in series, and ultimately the vehicle is driven only by the motor, not by the engine and the motor at the same time. This is very different from Toyota's hybrid system.

In engine drive mode, the i-MMD system completely separates the engine and generator, and the engine is only responsible for driving the vehicle. However, Toyota's THS-II system will generate some unnecessary energy consumption because the engine and generator are always connected.

In short, Toyota's THS-II system works on the premise of mixing the engine and the motor, and it cannot work with just the engine or just the motor.

Summary: "Mixed" well

From a technical perspective, Honda's heavily hybrid power system is designed with electric motors as the main power source and gasoline engines as the auxiliary power source. In hybrid mode, the gasoline engine is started only to charge the electric motor, which then drives the wheels. The gasoline engine is only connected to the wheels when cruising at high speeds. This can not only significantly reduce fuel consumption, but also provide strong power. Only by "hybridizing" like this can Honda live up to the expectations of many Honda fans.