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Custom gearbox design

The gearbox mainly refers to the gearbox of the car. It is divided into manual and automatic. The manual gearbox is mainly composed of gears and shafts. The gear shifting torque is generated by different gear combinations. The automatic gearbox AT is changed by hydraulic force. Torque, planetary gear, hydraulic variable pitch system and hydraulic control system. The variable speed torque is achieved by means of hydraulic transmission and gear combination.

The gearbox is a very important part of the vehicle, which can change the gear ratio and increase the torque and speed of the drive wheel. With the development of modern technology, the gearbox has also been upgraded. From the original manual transmission to the now continuously variable transmission, from no synchronizer to having a synchronizer, the control is more and more convenient. At present, diesel engines are widely used in construction machinery, and the range of torque and speed change is small, which cannot meet the requirements of traction force and running speed of vehicles under various working conditions. Gearboxes are needed to solve this contradiction. The performance of the gearbox is the key to measuring the dynamics, economy and drivability of construction machinery. The current shifting systems mainly include: mechanical transmission, hydraulic transmission, and hydrostatic transmission. The gearbox has manual shifting and power shifting, and the structure is fixed-axis and planetary.
Custom gearbox design

Features:
(1) Change the transmission ratio, expand the range of variation of the drive wheel torque and speed to adapt to the constantly changing driving conditions, and at the same time make the engine work under favorable conditions of high power and low fuel consumption;
(2) The vehicle can be driven backwards while the engine rotates in the same direction;
(3) Using neutral gear, interrupting power transmission, enabling the engine to start, shift, and facilitate transmission shifting or power output.
(4) The transmission is composed of a shifting transmission mechanism and an operating mechanism, and a power take-off can be added when necessary. There are two ways to classify: according to the change of the transmission ratio and the difference of the manipulation mode.

working principle:
The manual transmission consists mainly of gears and shafts, which produce variable speed torque through different gear combinations. The automatic transmission AT is composed of a hydraulic torque converter, planetary gears and hydraulic control system, through hydraulic transmission and gear combination. To achieve the variable speed torque.
Among them, the hydraulic torque converter is the most characteristic component of AT. It consists of components such as pump wheel, turbine and guide wheel, and directly inputs the engine power transmission torque and separation. The pump wheel and the turbine are a pair of working combinations. They are like two fans placed opposite each other. The wind blown by one active fan will drive the blades of the other passive fan to rotate. The flowing air—the wind becomes the medium of kinetic energy transmission. .

If liquid is used instead of air as the medium for transmitting kinetic energy, the pump wheel will rotate the turbine through the liquid, and then a guide wheel is added between the pump wheel and the turbine to improve the efficiency of liquid transfer. Because the torque converter's automatic variable torque range is not large enough and the efficiency is low.

The automatic transmission uses an auto-operated transmission, and the selection and shifting of the transmission ratio is automatic. The driver only needs to operate the accelerator pedal, and the transmission can control the actuator according to the load signal of the engine and the vehicle speed signal to realize the shift of the gear position.

 

Custom gearbox design

classification:
The gearbox has roughly the manual transmission, the ordinary automatic transmission/normal automatic transmission with the hand-integrated, the CVT continuously variable transmission/CVT geared gearbox, the dual clutch transmission, the serial transmission and the like.

Divided by transmission ratio
(1) Stepped transmission: The stepped transmission is the most widely used one. It uses gear drives and has several fixed ratios. There are two types of axial fixed transmissions (ordinary transmissions) and axial rotary transmissions (planetary transmissions), depending on the type of train used. The transmission ratios of passenger cars and light and medium truck transmissions usually have 3-5 forward gears and one reverse gear, and in the compound transmissions for heavy trucks, there are more gears. The so-called transmission number refers to the number of forward gears.
(2) Stepless transmission: The transmission ratio of the stepless transmission can be changed in an infinite number of stages within a certain range of values. Commonly, there are two types of electric type and hydraulic type (moving liquid type). The variable speed transmission component of the electric continuously variable transmission is a DC series motor. In addition to the application on the trolley bus, it is also widely used in the transmission system of the super heavy duty dump truck. The transmission component of the hydrodynamic continuously variable transmission is a torque converter.

The continuously variable transmission is a kind of automatic transmission, but it can overcome the shortcomings of "sudden shifting", slow throttle response, and high fuel consumption of the conventional automatic transmission. It consists of two sets of shifting discs and a belt. Therefore, it is simpler in structure and smaller in size than the conventional automatic transmission. In addition, it can freely change the transmission ratio, thus achieving full-speed stepless shifting, so that the car's speed changes smoothly, without the "ton" feeling of the traditional transmission shifting.

In the transmission system, the traditional gear is replaced by a pair of pulleys and a steel belt. Each pulley is actually a V-shaped structure composed of two discs. The engine shaft is connected to a small pulley and is driven by a steel belt. pulley. The mysterious machine is on this special pulley: the transmission pulley structure of the CVT is rather strange, and it is divided into left and right halves of the activity, which can be relatively close or separated. The cone can be tightened or opened under the action of hydraulic thrust, and the steel chain is extruded to adjust the width of the V-groove. When the cone-shaped disc is moved inwardly and tightly, the steel sheet chain moves in a direction other than the center of the circle (centrifugal direction) under the pressing of the cone disc, and instead moves inward toward the center of the circle. In this way, the diameter of the disk driven by the steel chain chain increases, and the transmission ratio changes.

(3) Integrated transmission: The integrated transmission is a hydraulic mechanical transmission consisting of a torque converter and a gear-type stepped transmission. The transmission ratio can be several intermittent ranges between the maximum and minimum values. There are no changes in the internals and there are more applications.

 

Custom gearbox design

(1) manual transmission
The manual transmission, also called the manual gear, can change the gear meshing position in the transmission by changing the gear shifting position by hand, and change the gear ratio to achieve the purpose of shifting. When the clutch is pressed, the shift lever can be adjusted. If the driver is skilled, the car with the manual transmission is faster than the automatic transmission when it is accelerating and overtaking, and it is also fuel efficient.
The AMT gearbox is a type of manual gearbox. It has the advantages of fuel-saving and low price. The disadvantage is that the application model is few and the technology is not mature enough. If the "hands-on-one" is to make the ordinary automatic transmission have the feeling of manual gear, then the AMT gearbox is just the opposite. It is based on the manual gearbox, and the overall structure remains unchanged by changing the shifting manipulating part. In the case of an automatic control system to achieve automatic shifting, it is like a robot to complete the two actions of operating the clutch and gear selection. Because it is essentially a manual transmission, AMT also inherits the advantages of manual transmission in terms of fuel economy. During the driving process, the AMT's sense of frustration due to gear changes still exists.

(2) Automatic transmission
The automatic transmission uses a planetary gear mechanism for shifting, and it can automatically shift the speed according to the degree of the accelerator pedal and the change of the vehicle speed. The driver only needs to operate the accelerator pedal to control the speed.
In general, there are several types of automatic transmissions commonly used in automobiles: hydraulic automatic transmissions, hydraulic transmission automatic transmissions, electric transmission automatic transmissions, stepped mechanical automatic transmissions, and stepless mechanical automatic transmissions. Among them, the most common is the hydraulic automatic transmission. The hydraulic automatic transmission is mainly composed of a hydraulically controlled gear shifting system, and mainly includes an automatic clutch and an automatic transmission. It automatically shifts gears based on changes in throttle opening and speed. A continuously variable transmission is a type of automatic transmission.

Divided by manipulation
(1) Forced-controlled transmission: The forced-actuated transmission is operated by the driver directly by shifting the shift lever.
(2) Automatically operated transmission: The transmission ratio selection and shifting of the automatic steering transmission is automatic, so-called "automatic". It refers to the transformation of each gear of the mechanical transmission by means of a signal system reflecting the engine load and the vehicle speed to control the actuators of the shifting system. The driver only needs to operate the accelerator pedal to control the speed of the vehicle.
(3) Semi-automatically operated transmission: There are two types of semi-automatic transmissions: one is the automatic operation of several gears commonly used, the other gears are operated by the driver; the other is pre-selection, that is, the driver pre-use The selected position of the button, when the clutch pedal is depressed or the accelerator pedal is released, an electromagnetic device or hydraulic device is turned on for shifting.

In the long-term use process, due to the frequent shifting, the components in the gearbox are inevitably worn and deformed, which causes the gearbox to be difficult to be geared, automatically disengaged, and noise during operation, which affects the use. Therefore, in daily use, it is necessary to carry out full-load operation check on the working condition of the gearbox frequently, observe whether the transmission of the transmission is stable, whether there is abnormal gap and noise, and find out the reason for adjustment or repair. Common faults are as follows:

Difficult to hang
When manipulating the shift lever, it is very laborious to lock the gear, and it cannot enter the gear smoothly; or the toothing sound occurs when the gear is locked, and the gear is not caught when it is serious.

The reasons are as follows:
(1) The clutch is not completely separated and the power cannot be completely cut off. The specific performance is two aspects: First, due to improper manipulation, the pedal does not step to the end, resulting in incomplete separation and difficulty in hanging. This phenomenon is common in novices. Because of the unskilledness, the pedals are often not blocked when they are stepped on the pedals, and the gears are not in the upper position, and the gears are squeaking. Second, it is difficult to lock the gears due to poor technical state of the clutch;
(2) The new gear teeth of the new car are rough, which makes the gearing difficult;
(3) The shift fork is loose and bent, the shift fork shaft is bent and rusted, and the movement is difficult. When the lock screw of the fork shaft fixed fork is loose, the gear shift is also difficult;
(4) The length of the reverse lever on the shift lever is improperly adjusted. When the reverse gear is engaged, the height of the locking piece is not enough to enter the reverse position.
Automatic off-range
There are two common situations in which automatic shifting occurs. One is that while driving, slightly raise the accelerator pedal, the gear jumps back to the neutral position; the other is that when the uphill load increases, the gear immediately jumps back to the neutral position. In this case, if you re-hang If the block is not hung up, it is easy to form a slope and a serious accident occurs.

The reasons are as follows:
(1) The spring of the fork spring is weakened or broken, so that the self-locking position fails;
(2) The fork locking screw is loose, the steel ball of the fork shaft positioning groove or the self-locking device is worn, and the shift lever cannot be reliably positioned;
(3) The effective stroke of the fork is small or the fork is bent and deformed, so that the gear meshing is not in place, and it is easy to disengage after being stressed;
(4) The end face of the fork is seriously worn, the gap between the end face of the fork and the sliding gear ring groove is too large, and the sliding gear is easy to shift forward and backward and automatically disengage; and so on
Gearbox abnormal noise
There are two cases of abnormal noise in the gearbox: one is abnormal noise in the neutral position; the other is abnormal noise when shifting while driving.

Custom gearbox design

Maintenance method:
More and more cars are equipped with automatic transmissions. With the automatic gearbox, people can drive the car between one foot and one foot brake, which is very easy. If the owner ignores the maintenance of the automatic transmission, the delicate automatic transmission is prone to failure.
The most easily overlooked by the owner is the correct selection and replacement of the automatic transmission oil on time. In addition to the usual correct driving, the key to maintenance is to "change the oil" correctly. It is important to note that the automatic transmission fluid (ATF) specified by the manufacturer must be used, otherwise the automatic transmission will be subject to abnormal wear. Replacing the automatic transmission oil cannot be done at a roadside shop or a car beauty shop because this operation is very strict. There are two series of automatic transmissions in the world, using two series of standard automatic transmission oils, which cannot be interchanged and mixed, otherwise the automatic transmission will be damaged. Therefore, to replace the automatic transmission oil, the owner must go to a special maintenance factory or a professional automatic transmission repair shop.
Under normal circumstances, the automatic transmission car should be cleaned and maintained once every 20,000 km to 25,000 km, or when the gearbox slips, the water temperature is high, the shift is slow, and the system leaks and cleans.

Precautions:
1. Master the cycle of replacing the automatic transmission oil.
The internal control mechanism of the automatic transmission is very precise, and the clearance is small, so most of the automatic transmissions have a oil change interval of two years or 40 to 60,000 kilometers. In the normal use process, the operating temperature of the transmission oil is generally around 120 degrees Celsius, so the quality of the oil is very high and must be kept clean. Secondly, after the transmission oil has been used for a long time, it will produce oil stains, which may form sludge, which will increase the wear of the friction plates and various components, and also affect the system oil pressure, which will affect the power transmission. Third, the sludge in the dirty oil will cause the movement of the valve body in each valve body to be unsatisfactory, and the oil pressure control is affected, thereby causing an abnormality in the automatic transmission. Always check.
2. Replace the transmission oil properly.
The better oil change method is dynamic oil change. The special gearbox cleaning equipment is used. During the operation of the gearbox, the old oil is fully circulated, and the new gearbox oil is added after the discharge, so that the oil change rate is as high as possible. More than 90, to ensure a good oil change.
3. Whether the automatic transmission oil level is normal.
The automatic transmission oil inspection method is different from the engine oil. The engine oil is checked in the cold state, and the transmission oil needs to preheat the oil to about 50 °C, and then the gear lever stays in each gear for 2 seconds. After being placed in the parking gear, the normal oil level of the dipstick should be between the highest and lowest lines. If it is not enough, the same quality oil should be added in time.

Custom gearbox design

Why should a car design a gearbox?

The role of the gearbox is to adjust the engine output and speed, switch between high speed and high torque, no gearbox, the engine speed directly affects the wheel, you can imagine, what is the speed of the car to reach a thousand revolutions per minute Feeling, and the speed range is limited. The above is for the internal combustion engine power. Electric vehicles do not have a gearbox because the speed can be controlled by the current output.

First, the gearbox structure

1. The gearbox consists of two parts: a variable speed transmission mechanism and a shifting control mechanism.

2. The main function of the variable speed transmission mechanism is to change the value and direction of the torque and speed; the main function of the operating mechanism is to control the transmission mechanism to realize the transformation of the transmission ratio, that is, to realize the shifting to achieve the variable speed torque.

Second, the structural characteristics

The simple transmission has the advantages of high efficiency, simple structure and convenient use, but the number of gears is small, and the range of i change is small (traction force and speed range are small), and it is only suitable for some turners with few gears.

Third, the principle

1. The mechanical gearbox mainly uses the principle of gear reduction.

2. Briefly speaking, there are multiple sets of different gear pairs in the gearbox, and the shifting behavior when the car is running, that is, the different gear pairs in the gearbox work through the operating mechanism.

3. If the gear is at a low speed, let the gear ratio work with a large gear pair, and at a high speed, let the gear ratio work with a small gear pair.

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