The structure and principle of operation of the tire pressure monitoring system TPMS
Security Systems,  Car device

The structure and principle of operation of the tire pressure monitoring system TPMS

Maintaining optimal tire pressure affects traction, fuel consumption, handling and overall vehicle safety. Most drivers use a conventional pressure gauge to check, but progress does not stand still and the electronic tire pressure monitoring system TPMS is actively being introduced in modern cars. For example, in European countries and the United States, it is mandatory for all vehicles. In Russia, the presence of the TPMS system has become a mandatory requirement for the certification of new types of vehicles since 2016.

What is TPMS system

Tire Pressure Monitoring System TPMS (Tire Pressure Monitor System) refers to the active safety of the vehicle. Like many other innovations, it came from the military industry. Its main task is to monitor the tire pressure and give a warning signal to the driver when it falls below the threshold value. It seems that tire pressure is not the most important parameter in a car, but it is not. First of all, it is driving safety. For example, if the pressure in the tires on each side of the axles is different, then the car will be pulled to the side. In basic trim levels, TPMS began to appear in 2000. There are also standalone monitoring systems that can be purchased and installed separately.

Types of tire pressure monitoring systems

In principle, systems can be divided into two types: with direct (direct) and indirect (indirect) dimension.

Indirect measurement system

This system is considered the simplest in terms of operation and is implemented using ABS. In motion, it determines the radius of the wheel and the distance that it travels in one revolution. ABS sensors compare the readings from each wheel. If there are changes, then a signal is sent to the car dashboard. The idea is that the radius and distance traveled for the flat tire will differ from the reference.

The advantage of this type of TPMS is the absence of additional elements and an acceptable cost. Also in the service you can configure the initial pressure parameters from which deviations will be measured. The downside is limited functionality. It is impossible to measure the pressure before the start of the movement, the temperature. The deviation from real data can be about 30%.

Direct measurement system

This type of TPMS is the most up-to-date and accurate. The pressure in each tire is measured by a special sensor.

The standard set of the system includes:

  • tire pressure sensors;
  • signal receiver or antenna;
  • Control block.

The sensors transmit a signal about the temperature and the state of the tire pressure. The receiving antenna transmits the signal to the control unit. The receivers are installed in the wheel arches of the car, each wheel has its own.

There are systems in which there are no signal receivers and wheel sensors communicate directly with the control unit. In such systems, the sensors must be “registered” in the block so that it understands which wheel has a problem.

Information for the driver can be displayed in different ways. In cheaper versions, instead of the display, an indicator lights up, signaling a malfunction. As a rule, it does not indicate which wheel is the problem. In the case of data output on the display, you can get information about the temperature and pressure for each wheel separately.

Pressure sensors and their varieties

Sensors are the key components of the system. These are complex devices. They include: a transmitting antenna, a battery, a pressure and temperature sensor itself. Such a device of controllers is in more advanced systems, but there is also a simpler one.

Sensors are distinguished according to their design and installation method:

  • mechanical;
  • external;
  • internal.

Mechanical sensors are the simplest and most inexpensive. They are screwed in instead of the cap. The tire pressure moves the cap to a certain level. The green color of the external valve indicates normal pressure, yellow - pumping is required, red - low level. Such sensors do not show exact numbers, and they are also often simply twisted. It is impossible to determine the pressure on them in motion. This can only be done visually.

External electronic sensors are also screwed onto the valve, but transmit a continuous signal at a certain frequency about the state of pressure to a display, indicator or smartphone. Their disadvantage is susceptibility to mechanical damage while driving and accessibility for thieves.

Internal electronic pressure sensors are installed inside the disc and are aligned with the wheel valves. All electronic stuffing, antenna and battery are hidden inside the wheel. A conventional valve is screwed on from the outside. The downside is the complexity of installation. To install them, each wheel must be bordered. The battery life of the sensor, both internal and external, usually lasts for 7-10 years. Then you need to make a replacement.

If you have installed wheel pressure sensors, be sure to warn the tire fitter about this. In most cases, they are cut when the rubber is replaced.

Advantages and disadvantages of the system

The following advantages can be highlighted:

  1. Enhanced security. This is one of the main and important advantages of the system. With the help of TPMS, the driver can detect a pressure fault in time, thereby preventing possible breakdowns and accidents.
  1. Saving. It will take some money to install the system, but it will pay off in the long run. Optimum pressure will help you fuel efficiently. The service life of the tires is also increased.

Depending on the type of system, it also has certain disadvantages:

  1. Exposure to theft. If it is impossible to steal the internal sensors, then the external ones are often twisted. The attention of irresponsible citizens can also be attracted by an additional display in the cabin.
  2. Malfunctions and malfunctions. Cars arriving from Europe and the USA often come with wheels removed to save space. When installing wheels, it may be necessary to calibrate the sensors. This can be done, but some knowledge may be required. Outdoor sensors are exposed to the external environment and mechanical damage, which can lead to their breakdown.
  3. Extra display (for self-installation). As a rule, expensive cars are initially equipped with a pressure control system. All information is conveniently displayed on the on-board computer screen. Self-installed systems have a separate display that looks alien in the cabin. Alternatively, install the TPMS module in the cigarette lighter. For long-term parking and at any time, you can simply remove it.

Possible TPMS malfunctions

The main causes of malfunctioning TPMS sensors can be:

  • malfunction of the control unit and transmitting device;
  • discharge of the accumulator of sensors;
  • mechanical damage;
  • emergency replacement of a wheel or wheels without sensors.

Also, when replacing one of the built-in sensors with another, the system may conflict and give an error signal. In Europe standard radio frequency for sensors 433 MHz, and in the USA it is 315 MHz.

If one of the sensors is out of order, then reprogramming the system can help. The response level of an inoperative sensor is set to zero. This is not available on all systems.

TPMS can display two error indicators on the dashboard: “TPMS” and “Tire with exclamation mark”. It is fundamentally important to understand that in the first case, the malfunction is associated with the operation of the system itself (control unit, sensors), and in the second with the tire pressure (insufficient level).

In advanced systems, each controller has its own unique identification code. As a rule, they come with the factory complete set. When calibrating them, a certain sequence must be followed, for example, front left and right, then rear right and left. It can be difficult to configure such sensors yourself and it is better to contact specialists.

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