CLUTCH OPERATING DEVICE WITH FRICTION LINING WEAR COMPENSATION ANALYSIS OF PROPERTIES AND UTILIZATION EFFICIENCY

In modern conditions of competition a lot of attention is paid to the comfort of driving. Control to driveline units is no exception. Application of clutch with the system of compensation of wear of friction overlays can not only enhance comfort, due to maintaining a stable effort on the pedal, but also improve the performance of the clutch. In the article a comparative analysis of the traditional design of the pneumohydraulic booster (PHB) and the design, which has a mechanism for compensating the wear of friction plate of clutches. As a compensator for the wear of friction plate of clutches, a telescopic rod with a closed cavity is used, which is filled the brake fluid through a reverse valve. With the wear of friction clutches, the fluid has the ability to slowly flow out of the closed cavity of the rod due to the leakage of the reverse valve. A positive feature is the ability to implement the proposed design within the framework of the traditional design of the pneumatic booster without changing the basic parts. As a result of the application of the proposed designs, it is expected to obtain such positive qualities as reducing the mass and material capacity of the product, maintaining high clutch performance regardless of the degree of wear of friction plates, reducing air consumption in operation (and, consequently, reducing fuel consumption), reducing the overall dimensions of the PHB. In order to confirm the new qualities, the consumption of air and fuel during the operation of both design of PHB on the typical urban route in the route bus is calculated. When calculating, the clutch exclusions taken into account are required during acceleration after each stop and traffic light. A reference to the investigation of the speed of the clutch control mechanism with new and worn friction plate of clutch is given. The properties of the proposed PHB design with the mechanism of compensation of the wear of the friction plate of the clutch are analyzed and the effect is shown not only in the manufacture of this design, but also from the application of this design in operation, which is expressed in fuel economy.


Introduction
The significant attention is given to the driving control in the modern competitive environment. The operation of the gearing system devices is not an exception.
The clutches with the wear compensation system allows not only to advance the comfort due to keeping the fixed pedal effort, but also to advance the operational features of the clutch [1].

Publication analysis
Plenty of authors in Ukraine and abroad pay attention to the development and improvement of the vehicle clutch control drives in their papers [2][3][4][5].

The objective and problem statement
The objective of this paper is to analyze the functional binding of the pneumohydraulic booster (PHB) with the clutch friction lining wear compensation. It is expected to get several positive alterations as the result of the suggested construction application:  the product mass and materials consumption reduction;  keeping the fast response time of the clutch, regardless of friction lining wear degree;  air consumption reduction during the operation (and as a result, the reduction of fuel consumption);  PHB overall dimensions reduction; Pneumohydraulic booster with the clutch friction lining wear compensation The great majority of the clutch constructions comprise no wear compensation mechanisms. In that case, the declutching pneumohydraulic booster constantly slides out the starting position of the piston component to keep zero clearance between the plug connector and the clutch bearing, so the operational features of the clutch drive go down with increase of the clutch wear [2]. The problem solution could be the PHB construction revision. As an alternative method to reduce the dimensions and PHB mass, along with the simultaneous clutch wear compensation, it is possible to consider the proposed construction with the PHB thrust rod that has two sections.
Due to the construction (Fig. 1a), the friction lining wear will be compensated for by the alteration of the thrust rod length, not by shifting the cylinder, as in the customary constructions. The force transmission between two sections of the thrust rod is carried out due to the closed void A (Fig. 1b).
The fluid supply to void A is carried out through the return valve 5. Due to the friction lining wear compensation system, the cylinder 1 ( Fig. 1), has the enclosure shorter than those of the customary constructions, and provides the travel that is necessary only for the declutching. The automatic wear compensation mechanism consists of two thrust rods: the inner 3 and the outer 11. There is the void А with the power fluid between them, and it is separated from the disconnecting gear by the ball with the return valve 5.
The operating principle is similar to the hydraulic rocker compensating gear in the variable valve event and lift. When pressing on the clutch pedal, the working fluid pressure enters the void between two thrust rods through the return valve and pushes the inner thrust rod off as far as it can go. Besides, it opens the speed valve 13 (Fig 1.a), thereafter the air fills the force void B of the cylinder 1.
When moving forwards, the piston component 2 pushes the outer thrust rod 11, herewith, due to the locked return valve 5, the hydraulic void А between the piston components 11 and 3 becomes closed, and provides the transmission of force from the piston component 2 with the thrust rod 11, to the thrust rod 3.
When declutching, the air outlet from void B takes place and the whole mechanism returns to origin by the action of the counter springs. The clutch lining wears during the car operation, and that causes the stepwise small displacement of the thrust rod 3 inside the thrust rod 11, the manometer pressure that stays in the closed hydraulic void after declutching (when moving without declutching), is dumped through the leakiness in valve 5. The possible air bubbles in the closed hydraulic void are removed through the radial bores 4, that open on to the gutter filled with the foam material. When the booster activates, the thrust rod gutter 11 moves over the sealer 6, which provides the isolation of the closed hydraulic void A from the declutching circuit. а b а -the general view of the proposed PHB construction; b -the schematic diagram of PHB with the clutch friction linings wear compensation mechanism Figure 1. The proposed construction of the pneumohydraulic booster In order to verify the effectiveness of the implementation of the proposed construction, we will estimate the air and fuel savings using the example of the route with the following buses: MAN A10 or MAN A15.
As an example, we will provide the map of the first route (Fig. 2), where the buses MAN A10 or MAN A15 operate. The overall length of the distance is 7 km. The route has 7 bus stops, 4 traffic lights, 7 crosswalks. The total traveling time is 11 minutes and 30 seconds, upon the condition of no delays Let us estimate the MAN А10 fuel consumption for the PHB construction with the friction lining wear compensation mechanism and with the minimum initial volume of the void B ( Fig. 1 Let us carry out the similar estimation with the maximum initial volume of the void B (Fig. 1, а) The difference between the distance S, km, and the volume of the fuel Q, l, between the compressor operation at the maximum and minimum volumes 1