SU737257A1 - Apparatus for remote control of vehicle transmission - Google Patents

Description

(54) DEVICE FOR REMOTE CONTROL OF VEHICLE TRANSMISSION TRANSMISSION

one

The invention relates to a transport technique, namely to devices for remote control of multi-stage transmission boxes of vehicles having multi-plate friction clutches and hydraulic cylinders for switching stages.

To reduce the dynamic loads during gear shifting in hydraulic transmission control devices, mechanisms of various designs are used to ensure a smooth increase in pressure in the hydraulic cylinders of the friction clutches. Structurally, the smoothness mechanisms are located either outside the hydraulic cylinders and are part of an external control system with respect to them, or in the hydraulic cylinders of the friction clutches. In the latter case, the design of the clutches is greatly complicated, as well as the efficiency and reliability of the gearbox, as in the event of a failure of the smoothness mechanisms, complete disassembly of the gearbox is necessary. On the other hand, in known designs, it is not possible to ensure satisfactory smoothness of engaging the sleeves with external devices.

A device for remote control of a gearbox with an external arrangement of smoothness mechanisms is known, comprising a switching mechanism for alternately supplying the working fluid from its 5 source to the hydraulic cylinder of the gearbox friction clutch, the outputs of which are communicated with the said hydrocilers by means of connecting lines, and smoothness mechanisms connected to the connecting line m parallel to 10 hydraulic cylinders 1.

The disadvantage of this device, as well as other devices in which the smoothness mechanisms are located outside the hydraulic cylinders, is that the quality of its operation depends on the magnitude of the hydraulic resistance.

15 lines located between the points of connection of smoothness mechanisms and hydraulic cylinders. The trigger pressure (initial setting) of each smoothness mechanism must be at least the pressure occurring at its connection point.

20 during the movement of the fluid (filling the hydraulic cylinder with liquid), i.e. it must exceed the pressure in the hydraulic cylinder by the amount of hydraulic losses in the connecting line. As a result, when the piston stops, the pressure in the hydraulic cylinder instantly increases to a value corresponding to the setting of the mechanism, which in a number of modes leads to a shock increase in the moment of clutch friction, dynamic loads in the transmission and deterioration of the vehicle's comfort. The purpose of the invention is to improve the reliability of the transmission by reducing the shock loads when friction clutches are engaged. The goal is achieved due to the fact that the known device is equipped with flow tubes, the number of which corresponds to the number of hydraulic cylinders of the friction clutches, with the input of each flow tube communicating with the corresponding output of the switching mechanism, the output with the appropriate mechanism for smoothing the coupling, and the lateral retraction of each flow tube with the corresponding hydraulic cylinder of the friction clutch, and the hydraulic resistance of each connecting line between the rammer The breech and smoothness mechanism is less than the hydraulic resistance of the connecting line between this flow tube and the hydraulic cylinder. FIG. 1 shows a device for remote control of a multi-stage gearbox; in fig. 2 shows the design of a flow tube of the venturi type; in fig. 3: - change in fluid pressure in the flow tube of the venturi type; in fig. 4 shows graphs of measuring various parameters when the friction clutch is engaged. The design of the device is described in relation to the two friction clutches of the gearbox. Gearbox 1 has multi-plate friction clutches 2 and 3 for switching gears mounted respectively on shafts 4 and 5 (Fig. 1). They consist of packages of friction disks 6, 7 associated with gearbox elements (not shown) and hydraulic cylinders 8, 9 with pistons 10, 11 located opposite the disk packages. To alternately supply the working fluid to the hydraulic cylinders of the friction clutches, there is a switching mechanism 12, the inlet of which by channel 13 is connected to the pump 14 and to the regulator 15 of the pressure of the pump 14, and the outlets connect the main lines 16, 17 to the inlets of the flow tubes, for example Venturi 18, 19. Mechanism 12 has three positions. In the middle position, both outputs 16 and 17 are connected to the drainage line 20. In the extreme positions, one of the outputs is alternately connected to the channel 13, and the other to the drainage line 20. Structurally, the mechanism. iaa.iAs - Sv s - .- - o JJ-irt i., - ii -.

737257 12 can be a hand selector with electric, pneumatic or other remote drive and a number of positions more than three, or a reverse mechanism (then clutches 2 and 3 correspond to forward and reverse clutches), or switching automatic control hydraulic valve. Venturi tubes 18 and 19 have, respectively, 1 inputs and outputs 21, 22 and 23, 24, as well as lateral outlets 25 and 26. To outputs 23 and 24, connecting lines 27 and 28 are connected to mechanisms of smoothness 29 and 30 of the same design, which are adjustable variable pressure tori. In particular, the mechanism 29 consists of a normally closed pressure regulator 31 with a drain line 32 and a spring 33, the setting of which is changed by the hydraulic cylinder 34. The hydraulic cylinder pressure is supplied from line 27 via the throttle 35, in parallel with which the backflow check valve 36 is installed. The same device has a smoothness mechanism 30, as a result of which all its elements are further designated by the same numbers as the similar elements of mechanism 29. The lateral taps 25 and 26 are connected by connecting lines 37 and 38 to hydraulic cylinders 8 and 9 of couplings 2 and 3. The throttles 39, 40 are the total (equivalent) hydraulic resistances of the lines 37, 38 from the Venturi tube to the hydraulic cylinders. Similarly, the chokes 41, 42 represent the equivalent resistances of the lines 27, 28 from the outlets of the Venturi tubes to the drain lines 32, including the internal resistances of the regulators 31. A possible embodiment of the flow tubes of the Venturi type 18 and 19 is shown in detail in FIG. 2. The housing 43 of the Venturi tube is installed in the channel 44 of the housing 45 of the gearbox or its components. The internal cavity 46 of the housing 43 has a shape characteristic of the Venturi tubes. The radial holes 47 of the narrow portion of the internal cavity 46 are in communication with the annular groove 48 on the housing 43. The groove 48 and the holes 47 serve as a side outlet from the converting device to the channel 49 of the housing 45. The device operates as follows. Work on the neutral (Fig. 1). The switching mechanism 12 is in a neutral (middle) position. The pump 14, driven from the input shaft of the gearbox 1, creates pressure in the channel 13, which is maintained at a constant level by the pressure regulator 15. The hydraulic cylinders 8 and 9 are connected by lines 37, 16 and 38, 17 through the venturi tubes 18 and 19 and the switching mechanism 12 communicates with drain line 20. Due to / of this clutch 2 and 3 are turned off and gearbox 1 is in the neutral position. The smoothness mechanism 29 is prepared to operate: the pressure in the hydraulic cylinder 34 is absent, the spring 33 is clamped, and the pressure regulator 31 is set to Low pressure P. The mechanism 30 is in the same condition. Switching on the friction clutch 3. To enable the steps in gearbox 1, corresponding to the clutch 3, the switching mechanism 12 is shifted to the left position. The line 17 is connected to the pressurized channel 13 and the working fluid is supplied to the hydraulic cylinder 9. Hydro-cylinder 8 by line 16 is still connected to the drainage line 20. The inclusion of the coupling 3 occurs in three stages, described below (Fig. 3 and 4). First stage. Filling the hydraulic cylinder 9. Filling the hydraulic cylinder occurs when Porsch 11 moves to the right (Fig. 1) all the way into the disc pack 7. At this stage, approximately a constant low pressure Pp determined by the force of the return springs and friction forces is established in the hydraulic cylinder 9. In a narrow section of the Venturi tube 19, a pressure 1 is established that exceeds the pressure P by the amount of losses at the throttle 40. The pressure P ° r of the initial adjustment of the smoothness mechanism (spring 33 settings) is equal to or slightly higher than the pressure Pj. Therefore, the controller 31 at stage 1 is closed and the pressure in line 28 in front of it is equal to Pf. The flow of fluid Qt through the venturi tube 19 at stage 1 depends on the pressure at its inlet Pwx, the pressure Pg in the hydraulic cylinder, and the value of the hydraulic resistance of the throttle 40. The second stage. The operation of the mechanism of smoothness and flow tube tube type venturi. When the piston 11 is stopped in the right position (Fig. 1), the movement of fluid in the line 38 stops, the pressure in all lines x behind the switching mechanism 12 starts to increase simultaneously. When the pressure value is reached in line 28, the regulator 30 opens, the fluid flowing through the venturi tube 19 begins to drain into the regulator drain line. The flow rate Qn of the fluid in line x 17, 28 depends on the pressures of the PBX, RPA and the resistance of the throttles 42. As it passes through the Venturi, the flow in its middle part narrows, as a result of which its velocity increases and the static pressure in the flow decreases. fluid goes into kinetic. Since the RTC pressure at the tube inlet at the first and second stages can be assumed to be the same and approximately equal to the adjustment pressure of the regulator 15, the static pressure in a narrow section of the Venturi tube is the smaller, the greater the flow rate (flow) of the fluid (at Р Рв). This condition is due to the fact that the hydraulic resistance of droplets 42 is significantly less than the resistance of droplets 40. For example, the smoothness mechanism 30 can be installed directly near the Venturi tube, and the clutch 3 is structurally more distant from it. In addition, line 28 may have a significantly larger section than line 38. In the second stage, the static pressure at the outlet of the Venturi gear is always higher than the pressure P in its narrow section, as the flow of liquid at the outlet expands (slows down) and part of the kinetic energy is again transformed into a potential. Since at the second stage the pressure in line 28 exceeds the pressure. the hydraulic cylinder 34 operates, gradually increasing the deformation of the spring 33 and, accordingly, increasing the pressure of the regulator 31 adjustment. The duration of the regulator adjustment process is set by the throttle 35, which determines the filling time of the hydraulic cylinder 34. Thus, in the proposed design, the static pressure in the narrow section of the Venturi tube 19 decreases in the initial moment after opening the smoothness mechanism. This is due to the fact that after the piston 11 stops, the fluid flow in the venturi tube, which rotates 90 ° into the lateral outlet, rushes in the forward direction. By selecting sections of the Venturi tube and droplets 42, the pressure is chosen such that the Pf value at the initial moment of the second stage is approximately equal to the pressure Pp in the hydraulic cylinder 9. As a result, the transition from the first stage to the second will occur without a sudden increase in pressure in the hydraulic cylinder to the RPA value of the smoothness mechanism setting 30, which leads in known constructions to shock switching on clutch 2. As the setting pressure of the regulator 31 increases, the amount of liquid it drains decreases, as a result of which the pressure РВ in a narrow section Venturi tube and, accordingly, in the hydraulic cylinder 9 increases. At the end of the second stage, the set pressure approaches the pump pressure value and the controller 30 closes. At a certain pressure RG, the moment of friction of the disk package of clutch 3 reaches a value equal to the moment of resistance, and the clutch is turned on. Depending on the load (moment of resistance), the coupling is switched on at different pressures, i.e. the switching time varies.

The third stage. Work included clutch.

At this stage, the mechanism of smoothness 30 nov closed. The pressure in all points of the maistral 17, 28, 38 and the Venturi tubes 19 to the hydraulic cylinder 9 is the same and equal to the pressure in the channel 13 supported by the regulator 15.

The processes described are depicted in a graph showing the static and velocity changes along the length of the lines from the entrance to the Venturi to the smoothness mechanism (Fig. 3). The dot-dash-dotted line on the line A represents the piezometric line at the first stage, the fat line B - the piezometric line at the beginning of the second stage, and line C - the full head also at the beginning of the first stage. The total head line corresponds to the Bernoulli equation, with some simplifications made for consistency. In particular, the geometrical component of the head is not taken into account due to its smallness and hydraulic losses along the length of a narrow section of the Venturi tube, jg

The shaded part of the graph is the velocity component.

h - | -V full head (y - specific gravity

but

liquids, flow rate, g - acceleration of gravity).

At the first stage, in the area from the narrow section of the Venturi tube to the smoothness mechanism, a constant pressure PB (line A) is established, equal to the sum of the pressures in the JQ hydraulic cylinder P and the pressure loss from the cutting chamber to the hydraulic cylinder.

At the second stage, the pressure in this area varies along curve B, and in a narrow section of the tube a pressure of 35 PB is established; When leaving the tube, the pressure of the flow increases (due to a decrease in the velocity head) to a value of P # X exceeding Pj, the setting pressure of the smoothness valve 1. The valve is open and passes the flow rate Q, as a result of which in line 28 there is a pressure loss at the throttle 42. Due to the slowing down of the flow, the output pressure exceeds the pressure in a narrow section by the value of the differential pressure wave; j determined mainly by the geometrical dimensions of the restriction device and representing the loss of velocity head in its expansion region. Obviously, this value can be arbitrarily set, provided that the resistance 50 is less than the resistance of the OR, can exceed the value of DSR. FIG. 2 is a picture of the case where DR Д DR, and RP RP, i.e., the pressure in a narrow section of the Venturi tube at the beginning of the second stage is reduced to the pressure in the hydraulic cylinder that occurs at the end of the second stage. This reduction is the main effect of using the venturi.

More clearly, this effect can be seen in graphs illustrating the change in pressure and friction torque of coupling M over time t (Fig. 4). The displacement X of the piston 9 corresponds to the constant flow Qj. When the vehicle is stopped (Qi 0), the smoothness mechanism works, creating a variable flow rate QK.

As a result, the mechanism pressure RV in a narrow section of the Venturi tube drops from Pg to RV and equalizes with the pressure of the RG in the hydraulic cylinder. Subsequently, the lines of these pressures merge and increase from the value of Rad (a thick line on the graph). At this time, the pressure at the entrance to the smoothness mechanism varies along the RPA curve, which lies above the Pg Pe curve.

The shaded area between them shows the decrease in pressure in the hydraulic cylinder provided by the venturi. The dot-dash shows a possible variant in which P as the second stage becomes lower than the pressure Pp.

Curve P shows pressure changes in conventional structures without the use of restriction devices. It is seen that at the end of the first stage, the pressure in the hydraulic cylinder increases abruptly from P to RPL and then is equal to the pressure of the smoothness mechanism. The magnitude of the jump is numerically equal to the hydraulic losses in the connecting line of the hydraulic cylinder and is fundamentally unavoidable, since the smoothness mechanism must be closed in the first stage.

t

The increase in the friction torque M ") of the coupling, proportional to the pressure in the hydraulic cylinder, occurs smoothly, without abrupt transitions. The closure of the coupling occurs at point D at the minimum external load, and at point B at the maximum external load (Fig. 4). Compliance with the slipping time of the coupling tmm and tm. In this case, the time t min can be chosen so that the accelerations of the elements connected by the clutch do not exceed the permissible limits.

In known constructions, the change in the friction moment occurs along the curve M. Here, the transition from the first stage to the second stage is accompanied by a jump-like change in the friction moment, which repeats the pressure jump P in the hydraulic cylinder. As a result, at minimum and average load, the coupling closes at point D. The slipping time here is practically zero and the instantaneous closure of the coupling is accompanied by the shock application of the load and the connecting element of the gearbox.

Thus, unlike conventional methods of use, the venturi in this case operates in two modes. In the first of them, the entire fluid flow with a rotation of 90 ° goes to the side outlet, and in the second mode the entire flow passes

out (without turning), as in ordinary cases. In this case, the “straightening of the flow occurs automatically. In order to reduce the hydraulic resistance from the Venturi tube in the first mode, the lateral retraction can be performed in the form of several radial holes 47, which are connected to the annular groove 48 on the housing 43 (Fig. 2)

When clutch 2 is turned on, the device operates in the same way. It is also obvious that with a larger number of couplings, each of them can be equipped with a smoothness mechanism connected via a Venturi tube, as described above.

As smoothness mechanisms, devices other than those shown in FIG. 1, including various batteries and other structures connected in parallel to the hydraulic cylinders.

The advantage of the construction described above is that due to the use of Venturi tubes, the adjustment of the smoothness mechanisms, regardless of the length and hydraulic resistance of the connecting lines, can be chosen based on the required signs of frictional friction moment rise. The consequence of this is, in particular, the possibility of significant control over the design of the clutch shaft gearboxes, since there is no need to place smoothness mechanisms inside their hydraulic cylinders. The smoothness mechanisms as described above can be installed outside the friction clutches - in the remote control mechanisms in the same way as in planetary gearboxes.

In addition to the Venturi tubes, other types of flow tubes can be used, such as Venturi nozzles.

Claims (1)

Invention Formula A device for remotely controlling a vehicle's gearbox, comprising a switching mechanism for supplying working fluid from its source to hydraulic cylinders of friction clutches of the gearbox, the outputs of which communicate with said hydraulic cylinders via connecting lines, and smoothly engaging mechanisms of friction clutches connected in parallel to hydraulic cylinders, that, in order to increase the reliability of the transmission by reducing shock loads when friction clutches are engaged, it equipped with flow tubes, the number of which corresponds to the number of hydraulic cylinders of the friction clutches, the input of each flow measuring tube communicating with the corresponding output of the switching mechanism, the output with the corresponding smoothness mechanism of switching on the coupling, and the lateral removal of each patern metering tube each connecting line between the flowtube and the smoothness mechanism is less than the hydraulic one. connecting line between this flow tube and hydraulic cylinder. Sources of information taken into account in the examination 1. US Patent No. 3691872, cl. 74-864, 1972 (prototype). 1 6 FIG. t