DE1926302C - Hydrostatic transmission - Google Patents

Description

One such hydrostatic transmission with a

The invention relates to a hydrostatic shut-off valve of this type, but still has the UnGear with infinitely variable adjustment perfection on that when switching rl

<t

operation while the pump stroke is being reduced is no longer possible. In contrast to the

volume, the shut-off valve responds immediately and thus the subject matter of the invention thus requires the known

the effect is that despite a relief of the discharge gear to prevent overspeed of the

load valve (for the desired short-circuiting of the pump, a specific flow rate adjusting device.

Transmission circuit) during this switching process 5 Furthermore, it is already known (USA.-Patentschnft

it is not possible to short-circuit the circuit. 2 789 542), with a hydrostatic transmission with

The invention is therefore based on the task of the open circuit, the pump delivery line and the an infinitely adjustable hydrostatic transmission return line via a separate pilot valve to design initially listed genus, tes overflow valve with a liquid tank that this disadvantage is eliminated and also connect during io. Those of the ones covered by the main lines During the gear changeover process, close the short-facing overflow valve front sides away of the cycle is possible. the control lines each lead to a pressure setting

To solve this problem, the hydro valve. The bias of these pressure adjustment valves

static transmission according to additional patent 1 926 253 and thus the opening pressure of the overflow valves

The piston of the shut-off valve (no-load protection valve) with ^l 5 can be adjusted using a brake-accelerator lever.

Delay means provided that a movement bar. The dial valves act as a development

of the piston in a connection between the load valves, so that both in the acceleration

Pressure adjustment valves and the relief valve as well as in deceleration mode the speed over-

delay locking position. Settlement setting is softly adjustable. The problem

The piston, which is under tension from a spring, corresponds to the overspeed of the pump at a torque of the The shut-off valve is expediently in a Boh- reversal does not occur due to the open circuit. tion displaceably arranged, which the outlet By the delay principle of the invention line of the check valves with an appropriate design is prevented from occurring at the relief valve leading line connects and in the loads of the relief valve, for example through a stationary pin protrudes of such strength that stepping down the clutch pedal too quickly into his between this and the inner wall of the bore locking position is moved.

of the piston in the flow of the return oil when the transmission from forward to reverse

Sliding down of the piston is an obstructive gap. gear is to be switched, “the stroke volume

The pin can expediently reduce the bore of the pump in the direction O on one. This creates

be arranged sealing plug. 30 a braking effect on the transmission output shaft,

This delay principle is inherently out of the and the direction of torque in the transmission is reversed

German Auslegeschrift 1 089 235 known. Here at, d. That is, the hydraulic motor acts as a pump. When

the cylinders on both sides of the piston indicate the driver together with this gear ratio change

Drischen approaches notches or grooves, which the tion also depresses the clutch pedal, speaks

Exit of the pressure oil to be displaced throttle-like 35 now with driving output and still

regulate as soon as such a cylinder attachment of the non-switched transverse piston (actuator

Piston rod into the bore of a cylinder cover for the pressure adjustment valves) the idle shut-off valve

immersed. too quickly and increases the effect of the trampled

It is also already known to open each valve of a clutch pedal, i. i.e. it will be a short pair High pressure relief valves via lines 40 circuitry of the hydraulic circuit despite "Crosswise" to the transmission high-pressure and the depressed clutch pedals prevented to connect the drive train pressure line. The over- the prerequisite that there is no high pressure in the flow slide are preloaded in the closing direction, the brake valve opens. So it would be with one and against the closing direction of the liquid switching process, e.g. B. from forward operation pressure from one of the two main lines 45 reverse operation, not be possible, the short circuit. Maintain the upstream connection in the overflow valve slide. To avoid this, The throttle openings are on the gearbox- the idling protection valve must be connected to the main delay lines be provided facing away overflow valve end faces, which delay its response side equipped with a pilot operated valve. This and thus when switching the transmission, for. B. from Pilot valve, which can be set arbitrarily by means of 50 forward to reverse operation, initially the from of a cam can be changed, is used for the high clutch pedal generated short circuit overpressure limitation and as a clutch valve, with the right hold.

the maximum transmission pressure can be reduced quickly. The invention is shown in the drawing on the basis of a

den can (British patent specification 950 612). Embodiment shown and in the following

From the USA patent specification 3,199,286, it is already explained in more detail.

known for braking the transmission output shafts. The drawing shows a pump-motor arrangement hydrostatic transmission with closed voltage 15, which inlet openings 21, 22 and 21 α Circuit between the two main transmission lines and 22 ″. These openings are marked with lines also such a pilot-controlled overflow 18 or 18a in connection and are through valve to be provided. The bias of the pilot control 60 lines 20a and 20 crosswise with high pressure valve can be connected to relief valves 19a and 19 by means of a brake lever. In these braking can be increased. The overflow valve are overflow slide valves 38 and 38a regardless of which of the main net, each of which has an end opening 48 or 48a lines straight high pressure leads. An overspeed, which in the transverse connecting lines 20 and number of the pump will lead to 65 20a in this gear. Stand on opposite ends prevents the pump from acting on valves 38 or 38 "via lines 46 or 46" before braking Flow rate is set to zero. An influencing with a valve arrangement 49 in connection, in the the pump speed from the transmission output side, two identical valve supports 51 and 51 «mil each

a Druckeinstellvcntil 84 or 84o and each one tion and the guide pin is pressed, whereby

Check valve 82 and 82 a are arranged. has a dampening effect on the movement of the

The valves 84 and 84 a are provided by vertical pistons. If the viscosity of the hydraulic piston 130 or 130 'is actuated, on each of which a pen fluid is known, the space can be arranged so that the valve is unseated from its seat so that it lifts for the movement of the piston can. The two pistons are in contact from their end position at the bottom of the bore 156 with a perpendicular to them arranged transverse to the point at which the piston just the piston 136, which interrupts paragraphs with reduced through-connection with the line 50, needed has knife. Over a period of time, the transverse piston 136 can be approximately the same as that which is actuated for a complete control linkage 140. In its Neu- io effect of the control device is necessary.
The vertical pistons 130 and 130a are in the central position. The line 50 leads to a mechanically adjustable middle part and lift the two ble relief valves 52 with a valve cone 57, pressure adjustment valves 84 and 84a from their seats. which the connection between the line 50 and

In the forward position, the transverse piston 136 of a line leading to the oil collecting container 10 is located

so that the vertical piston 130 in contact with 15 regulates 53/54. The valve cone 57 is

a reduced part of the transverse piston is so that closed position to interrupt the connection

the overlying Druckeinstellvcntil 84 from that between the lines 50 and 53 by a spring

above him is held pressed spring on his seat 80, which is against an axially slidable

while the vertical piston 130a is supported by the piston 66. Between the valve cone 57

Central part of the transverse piston 136 is raised and ao and the piston 66 a distance is provided which

the pressure adjusting valve 84a lifts off its seat. it allows the valve cone to be under the action

The check valves 82 and 82a rest on their one high pressure in line 50 of vseinem

Sit and regulate the connection between the lei- seat lift off and press together the

lines 46 and 46a and a channel 160. Spring 80 to move against piston 66.

The valve arrangement 49 also has an idle as can be seen from the drawing, but can

protection valve 146 on with a displaceable piston of the valve cone 57 also thereby from its seat

148, which is provided with a bore 150, in which the piston 66 is lifted to the right

a stationary guide pin 152 is housed. Which is moved, which is articulated by a

Guide pin is carried by a plug 154, bound pedal 76 can be made. The piston 66 is

which is screwed tightly into a bore 156, provided in 30 with a piston rod 68 with a

which piston 148 slides. The plug 154 is bracket 73 is connected to the one at 74

used sealed and acts as a system for an arm 75 of an angle lever in a rotatable connection

Spring 158 wrapping around guide pin 152 stands. The pedal 76 forms the other arm of the

between the plug and the upper face of the angle lever, which is around a fixed bearing 77

Piston 148 is arranged. 35 is rotatable. Between the arm 75 and the

The channel 160 causes a fluid connection. A tension spring 78 is arranged, which

between the upper part of the bore 156 and which the pedal urges upwards and the piston 66 in

Lines 46 and 46a via internal channels into which the interior of the valve 52 presses.

Valves 51 and 51 α, if the pressure is sufficient The mode of operation of the arrangement is as follows:

is high to check valves 82 and 82a of FIG. 40 Assume control linkage 140 is in place

to lift off their seats. in the forward position shown in the drawing

Another channel 162 establishes a connection, so the cross piston 136 is shifted to the right.

between the lower end of the bore 156 and ben, and the piston 130a becomes the pressure adjustment

ciner of the lines 46 and 46a, namely in the drain valve 84a from its seat, during the

depending on which of the pistons 130 or 130 a 45 piston 130 in contact with the reduced part

is so that it is the associated Druckcinslellventil 84 of the cross piston 136 and the Druckeinsteii-

or 84a lifts from its seat. valve 84 allowed to rest on its seat. Around-

F. approximately in the middle between the channels 160 and turned in the inlet openings 21 and 22

162, the bore 156 is provided with an opening, the pressure can develop through the transverse

to which a line 50 is connected. The arrangement 50 connecting line 20a, through the opening 48a and

The opening of this opening is selected so that a connection through the line 46a with the valve 51a

Communication between channel 160 and line 50 is communicated.

is established when the piston 148 is at the lower Da the pressure adjusting valve 84 is closed and the

End of the bore 156 is located. When the pressure adjustment valve 84a is open, the channel 162 is open

Piston 148 upwards, the opening is opened 55 and the bottom of the piston 148 is

closed and the line 50 from the bore 156 device 46 transmitted pressure during normal

severed. Reverse operations suspended. However, if the

The piston 148 becomes the hydraulic motor as a pump by reducing the pumping motor system 15

Pressure in channel 160 moves. The guide pin 152 and the pump act as a hydraulic motor (reversal of

has a predetermined distance from the wall 60 of the torque flow), which occurs when the

the hole 150. When the piston 148 is pushed into the vehicle or moved in the opposite direction

Its lower position is, it is constrained, so it develops in the openings

If the amount of liquid in the part of the bore 21a and 22a was correct, the pressure in the line 46

150, which is passed below the end of the, from where it is passed through the valve 51

Guide lifts 152 are located. If the piston 65 and the channel 162 now move to the bottom of the piston 148

148 upwards, the guide pin 152 is reached further. Then when the pedal 76 is depressed,

is pressed into the bore 150 so that the fluid becomes the liquid in the channel 160

(Hydraulic fluid through the gap between the BoIi- through the line 50, the relief valve! 52 and

the lines 53, 54 flow into the collecting container 10. As a result, the pressure in channel 160 (outlet line) is reduced, the higher pressure in channel 162 will push piston 148 upwards and close the access to line 50. As a result, a liquid flow through the lines 46 and 46a is prevented and also avoided that the valves 38 and 38a shift and cause a short but strong flow of liquid between the openings 21a, 22a and 21, 22. This is because the flow through the openings 48 and 48 "must be built up in order to bring about a pressure drop through the corresponding slide valves 38 and 38 a, which is necessary to generate enough force to move the valves and to short-circuit the hydraulic fluid cause. By preventing the circuit short circuit, the pump-motor system is prevented from running away and the power source that drives the normal pump is dynamically braked. Excessive pressure generated under such conditions is dampened in that the pressure setting valve 84a is opened, whereby a small amount of a liquid flow passes through the line 46, through the valve 51 and the channel 160 to the valve 51α and to the line 46a. Otherwise, the same results are obtained when the control linkage 140 is brought into the reverse position.

If the control linkage is quickly moved from the reverse position into the forward position, so the cross piston 136 is moved immediately to the Dmckeinstellventile 84 and 84 a in one position to bring that prevents forward movement. However, the servo drives require a certain amount Time before they manage to move forward, d. H. just before the rapid movement of the Control linkage 140 in the forward position, the servocontrollers are brought into a reverse position, whereby the swash plates for the pump-motor-system be pivoted in order to let the drive pressure in the openings 21 and 22 become effective, while the openings 21a and 22a are ready to receive the boost pressure from the charge pump. The servo controllers are, as they are generally known, not shown in the drawing.

In the forward position, the inlet opening 21, 21 α is exposed to the drive pressure which is fed to the valve 51 via the line 46. The line 46 a is normally only loaded with the much lower boost pressure that acts on the bottom of the piston 148, namely via the line 46 a, the valve 51 a, the open pressure adjustment valve 84 a and the channel 162 to the lower end of the bore 156 Since the transmission high pressure prevails in channel 160, which is reduced a little in valve 82, but is significantly higher than the pressure in channel 162, piston 148 will return to its lowest position. However, until the servo device can bring the dew disks of the pump motor system 15 from the forward position to the reverse position, the inlet openings 21, 22 will be exposed to the high pressure. As a result, line 46a would be exposed to high pressure when control linkage 140 is in the forward position and torque flow in system 15 is reversed. Then the high

ίο there is pressure in channel 162, and if the Operator depresses pedal 76 as instinctively will when the machine enters one Direction is driven and they suddenly interrupt the driving force in that direction and in the

»5 wants to bring the opposite direction, the liquid wedge through line 50, through relief valve 52 and lines 53 and 54 to the collecting container 10 stream.

The pressure reduction occurring in channel 160 as a result allows the pressure in channel 162 to be reduced Pressure to move piston 148 upward. The piston 148 can only move with the speed be moved upwards, with which the hydraulic fluid in the bore 150 through the gap between

see the guide pin 152 and the bore 150 can emerge. Since this gap is the exit of the If liquid from the bore 150 decelerates, the movement of the piston 148 will take place slowly and the line 50 has not yet been fully completed when the servo controller controls the swash plates of the pump-motor system 15 have swung back. Therefore, in the line 46 and in the valve 51 or in the open check valve 82a, in the channel 160, in the upper part of the bore 156, in the line 50,

between the open valve cone 57 and in the lines 53 and 54 up to the collecting container 10 hydraulic fluid is still flowing. This flow will suffice through the opening 48 a certain Letting pressure pass through is enough, that

Slide valve 38a, as shown in the drawing, to move to the right. The one in the opening 21,22 Developed pressure can then briefly passed through the cross connection 20a to the boost pressure port 21a, 22a will. When this occurs, no power can be transmitted through the pump-motor system 15 will.

From the foregoing it can be seen that the operator is in complete control of the Vehicle retains a rapid changeover from reverse to forward position, though has taken place, and cannot be surprised by an operating behavior which is the opposite of that of your chosen lies. In addition to this, all properties of the idle protection valve remain exist, which prevent the drive from running away and the associated possible damage, while the dynamic braking effects are retained.

1 sheet of drawings

Claims (1)

1 2 displacement machines (pump, hydraulic motor) Patent claims: _υΒ ^ _e j _nem closed fluid circuit, the 1st hydrostatic gear with a setting purpose to avoid overspeed of the pump device device continuously adjustable displacement machines with driving gear output shaft (e.g. with 3-energy (pump, hydraulic motor) and a closed 5 departure of a vehicle) by means of an overflow fluid circuit, which can be short-circuited in order to avoid control, which contains two precontrolled, overspeed of the pump when driving crosswise to the two main transmission lines of the transmission output shaft (e.g. when driving downhill an overflow valve connected to the vehicle ) can be short-circuited by means of an overflow control closing direction pretensioned overflow slide, which contains two precontrolled overflow valves, which are closed cross-over against the closing direction of the fluid pressure to the two main transmission lines from one of the two main lines en in which the closing direction of the pretensioned overflow slide valve facing away from the main transmission lines is connected to a control line opposite to the closing direction of the liquid and the two end faces are each connected to one of the pressure from one of the two main lines. The main transmission lines are bridged, so that each of the two control lines facing away from the overflow valve face is connected to a control line opening in the direction of the overflow valve, and the two pressure adjustment valve leads, which are coupled to one of the two overflow valve lines by means of a connecting face , and that both control means are bridged by a throttle bore, that ao lines each via a check valve with each of the two control lines to a common pressure leading to a liquid tank in the direction of the overflow valve no-adjustable relief valve are connected, whereby control valve leads, which are coupled by means of a connecting line, the pressure setting valves in a gear setting line, and that both control neutral or forward or reverse common lines via a check valve with a «5 or each individually are open and a shut-off valve is arranged in the common line leading to a liquid tank from the check valves to the relief valve, the adjustable relief valve verbund 1, which are, the pressure adjustment valves at a Ge of the difference in the pressures at the respectively open gear unit neutral or forward or reverse pressure adjustment valve and in the outlet line of the downward jointly or individually opened 30 non-return valves can be actuated and are predominant and in which the pressure on the pressure adjustment valve blocks from the non-return. Such a valve leading to the relief valve transmission line is the subject of the additional patent 1 926 253. A check valve is arranged, which is known from the Difference It is known (book by Jean Thoma "Hydrorenz der Drucke am Druckein- static transmission", 1964, p 119.120) for the locking valve and in the outlet line of the return of dangerously high speeds, an energy hammer valve can be actuated and, in the case of predominance, an annihilator to be used, which blocks between the pressure at the pressure adjustment valve, connected to the two main lines, additional throttle over patent 1 926253 , characterized in that the flow device is characterized in that the piston (148) of the locking drive motor diverts part of the oil flow into the return valve (no-load protection valve 146) with a delayed flow line. A separate control means (150, 152) is provided here, which requires a device that receives the impulses from the tachometer of the movement of the piston (148) in one of the connecting drive motors,
between the pressure adjustment valves (84 or such a speed limiting device is 84a) and the relief valve (52) blocking also from the German Auslegeschrift 1111 035 be-position delay. 45 knows, after the occurrence of an overspeed of the 2. Hydrostatic transmission according to claim 1, transmission input shaft an overflow control characterized in that the under voltage short-circuits the liquid circuit. a spring (158) standing piston (148) in a The hydrostatic transmission is displaceably arranged after the additional bore (156) , which patent 1926 253 allows, by means of an idling protection valve acting as the outlet line (160) of the check valves 50, that with one leading to the relief valve (52) when driving with reverse torque direction, line (50) connects and into which a stationary pin (152) protrudes, for example when pushing the output shaft, of such strength that when going downhill, there is no short-circuit position between this and the Inner wall of the bore flow valves as a result of the opening of the pilot valve (150) of the piston (148) a flow of the 55 acting, controllable relief valve enters. Pressurized oil when the piston slides down- This prevents that there is an additional gap when driving uphill. for example by mistakenly stepping on the clutch 3. Hydrostatic transmission according to claim 2, control pedal and thus when opening the relief, characterized in that the pin (152) on valve the transmission is short-circuited and the one of the bore (156) closing plug 60 gearbox output shaft is arranged unbraked its speed (154) is. can elevate. Despite preventing overspeed The braking effect of the transmission remains on the pump even if the clutch is operated incorrectly. pedal and thus the relief valve 65 hold.