CN104071219B - A kind of engineering machinery skid steer system - Google Patents
A kind of engineering machinery skid steer system Download PDFInfo
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- CN104071219B CN104071219B CN201410289775.5A CN201410289775A CN104071219B CN 104071219 B CN104071219 B CN 104071219B CN 201410289775 A CN201410289775 A CN 201410289775A CN 104071219 B CN104071219 B CN 104071219B
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Abstract
The present invention announces one can be in the time of engineering machinery heavy duty descending, and four-wheel, by under the state of locking, carries out front-wheel simultaneously and preferentially turns to the engineering machinery skid steer system of braking with trailing wheel. The present invention accesses the first pressure-gradient control valve in the brake fluid line of propons (steeraxle): in the time not turning to, and the sebific duct that is functionally equivalent to connection of the first pressure-gradient control valve, the brake fluid line of propons keeps connecting, and when after brake, can realize normal front-rear axle and brake simultaneously; In the time that propons need to turn to, under the effect of control-oil pressure, the brake fluid line of the first pressure-gradient control valve fast shut-off propons, the direct oil return case of pressure oil that makes propons, propons brake pressure is reduced to 0, now, propons just can be realized normal direction of rotation smoothly, and trailing wheel is always in braking state. After having turned to, under the effect of back-moving spring, make the first pressure-gradient control valve spool return, the instantaneous recovery again of pressure oil of propons connected, and after this, front-rear axle is braking simultaneously just.
Description
Technical field
The present invention relates to the engineering machinery of hydro-steering, four-wheel drive, specifically one can be in the time of engineering machinery heavy duty descending, and four-wheel, by under the state of locking, carries out front-wheel simultaneously and preferentially turns to the engineering machinery skid steer system of braking with trailing wheel.
Background technology
Engineering machinery is heavily loaded in the situation that, while travelling on smooth-riding surface, driver steps on brake pedal, four of complete machine tires are by locking completely often, because engineering machinery car body weight is than large many of family car, be again heavy duty, powerful complete machine inertia makes driver stepping on and to brake always, make the complete locking of wheel, control complete machine speed. Because the travel speed of engineering machinery is little more a lot of than automobile, unloaded maximum travel speed is generally no more than 40km/h, and the larger complete machine of weight, and the highest unloaded travel speed is less, and fully loaded time, tractive force can become greatly, and it is less that travel speed can become. Therefore,, while travelling in smooth-riding surface, driver can be by turning to or shifting to an earlier date brake locking tire with avoiding obstacles in advance.
But in the time of descending, even if the engineering machinery speed of heavy duty is very little, because the draw of gravity and the inertia of complete machine also make driver stepping on and to brake always, make wheel completely by locking, reduce the complete machine speed of service, now the wheel of complete machine and vehicle frame become a rigid body, four tire sliding motions forward simultaneously, even if driver's steering wheel rotation this moment, also cannot change the glide direction of vehicle, complete machine temporarily loses direction control. Due to engineering machinery construction in the wild mostly, the situation on road surface is very complicated, in the time that descending road surface is uneven, road surface just makes complete machine because of the disequilibrium of jolting to the active force of complete machine, existing force unbalance, also have the imbalance of moment, under the effect of out-of-balance force, complete machine has just lost control completely. Now, in the time that there is barrier in the front of complete machine sliding motion, complete machine is in braking state, and front axle tyre is by locking, and complete machine has just completely lost steering capability, in stays, therefore complete machine just in being in extreme danger, thereby cause occurring security incident.
The feature of engineering machinery:
1. car body quality is large, and more much bigger than family car, and the complete machine travelling has powerful inertia, is not easy to be checked car, therefore requires very high to brakes.
2. the speed of a motor vehicle is low, and general unloaded maximum travel speed is no more than 40km/h, far below the max. speed of automobile, and not taking the transport that runs away as main, but taking can be to restoration in earth-rock construction operation as main.
3. braking distance is short, once driver touches on the brake, it is maximum that brake force just reaches, and makes tire by locking, and skidding distance is the shortest. Compared with family car, the frequency of utilization of " point is stopped " is few. Especially in heavily loaded descending and brake hard, must locking tire.
4. because the speed of a motor vehicle is low, therefore after brake, seldom occur that the automobiles such as trailing wheel whipping, sideslip are in the phenomenon of appearance when brake and turning to of running at high speed.
5. many employing four-wheel drives, because overall mass is large, the tractive force that can provide in order to make full use of ground, industrial wheeled equipment all adopts even all-wheel drive of four-wheel drive, with increasing traction.
6. the hydro-steerings that adopt more, because Engineering Machinery Quality is large, car body heaviness, pure mechanical steering can not overcome the steering resisting moment of car body, and hydro-steering can provide very large steering moment, and turn to sensitive. For this reason, engineering machinery adopts hydro-steering more.
Engineering machinery is bulky, and often heavy duty, and once brake, most of tires are by locking, only slides and does not roll. Due to complete machine in motion, the level of security turning to will, higher than braking, not have direction ratio not brake more dangerous. For this reason, in the time of complete machine heavy duty descending, under seized state, allow the system of front-wheel steer just to become a solution, how to realize and allow front-wheel steer at four-wheel during by locking?
For the operating mode of above-mentioned engineering machinery, there is no concrete solution at present. Traditional design concept is: under normal circumstances, Engineering Machinery Quality is large and the speed of a motor vehicle is low, when brake, does not turn to, and while turning to, does not also brake. This traditional design concept has met most users' applying working condition. But the operating mode that each client uses is very complicated, for complete machine heavy duty descending operating mode: when braking, need to turn to and can not turn to this problem just to become the defect of traditional design theory.
Summary of the invention
For solving the problems of the technologies described above, the invention provides a kind of engineering machinery skid steer system.
The present invention is preferentially to turn to as principle, turning to prior to braking is theory, in the time of complete machine heavy duty down hill braking, if when driver need to turn to according to operating mode, pressure-gradient control valve can temporarily be removed the brake pressure of propons, propons is preferentially turned to, when turning to after end, pressure-gradient control valve spool self-return, brakes can be recovered rapidly the braking to propons, whole process back axle keeps on-position always, thereby carries out when realizing braking and turn to. Like this, complete machine still has normal steering capability when seized, has ensured that driver controls ability to the direction of complete machine, thereby can keep away in time sudden strain of a muscle barrier, protection driver's life security.
Due to rear lock, in the time that propons turns to, the inertia force that the automobile " weight of rear wheel bearing " of running at high speed produces can make complete machine produce the inertia torque around propons, because the quality of automobile is little, rotary inertia is also very little, and speed is very large, inertia torque can make automobile produce relatively rotating around propons, and relatively rotate lasting chronic, relatively rotate angle very large, therefore automobile there will be serious whipping, sideslip, thereby makes automobile completely out of hand, the life security that seriously jeopardizes driver. But the engineering machinery well below automobile driving speed there will not be this phenomenon completely, because rotary inertia is large, the speed of a motor vehicle is low, inertia torque make that complete machine produces around propons to relatively rotate the duration very short, relatively rotate angle also very little, therefore there will not be out of control phenomenon completely. For this reason, can realize the engineering machinery skid steer system of rear lock, front-wheel steer.
The present invention is achieved through the following technical solutions: a kind of engineering machinery skid steer system, comprises left steering cylinder, right steering cylinder, switching valve, foot brake valves, rear driving axle, front driving axle, steering gear and fuel tank;
Described left steering cylinder is connected with switching valve with right steering cylinder; E mouth on switching valve is connected with the second pump, and the D mouth of switching valve is connected to fuel tank;
L mouth and the R mouth of described steering gear are connected to switching valve, and the T4 mouth of steering gear connects fuel tank, and the P4 mouth of steering gear is connected with respectively the first pump and the first overflow valve; The described first overflow valve other end is connected to fuel tank;
The P1 mouth of described foot brake valves is connected with propons accumulator, and the K1 mouth of foot brake valves is connected to front driving axle; The P2 mouth of described foot brake valves is connected with back axle accumulator, and the K2 mouth of foot brake valves is connected to rear driving axle; T1, the T2 mouth of foot brake valves are connected to fuel tank;
To the oil circuit of front driving axle, be provided with first pressure-gradient control valve at the K1 of described foot brake valves mouth; Described the first pressure-gradient control valve is a hydraulic control two-bit triplet reversal valve, and the upper P3 of the being mouth of the first pressure-gradient control valve is communicated with K3 mouth, its next T3 of being mouth is communicated with K3 mouth; The P3 mouth of the first pressure-gradient control valve is connected with the K1 mouth of foot brake valves, and the K3 mouth of the first pressure-gradient control valve is connected to front driving axle, and the T3 mouth of the first pressure-gradient control valve is connected to fuel tank; The upper control chamber of the first pressure-gradient control valve is provided with back-moving spring;
Between described steering gear L mouth and the outlet oil circuit of R mouth, be connected with the first shuttle valve, the oil-out of the first shuttle valve is connected with hydraulic control one-way valve; The A2 mouth of described hydraulic control one-way valve connects the oil-out of the first shuttle valve, and the B2 mouth of hydraulic control one-way valve connects the V mouth of control chamber under the first pressure-gradient control valve, the K2 mouth of the U mouth pin brake valve of hydraulic control one-way valve.
It is further: in described foot brake valves K2 mouth is connected to the oil circuit of rear driving axle, be provided with pressure switch.
The T1 of the first described overflow valve, the D mouth of switching valve, foot brake valves and the T3 mouth of T2 mouth and the first pressure-gradient control valve are connected to fuel tank by a fine filter.
In the oil circuit at described fine filter oil-in place, be connected with the choke valve and the cooler that are connected in parallel.
The first described pump and the oil-in of the second pump are connected to fuel tank by a coarse filter.
The present invention accesses the first pressure-gradient control valve in the brake fluid line of propons (steeraxle): in the time not turning to, the function of the first pressure-gradient control valve is equivalent to the sebific duct of connecting, and the brake fluid line of propons keeps connecting, and when after brake, can realize normal front-rear axle and brake simultaneously; In the time that propons need to turn to, the first pressure-gradient control valve is realized fast the brake fluid line that cuts off propons under the effect of control-oil pressure, makes the direct oil return case of pressure oil of propons, be that propons brake pressure is reduced to 0, now, propons just can be realized normal direction of rotation smoothly, and trailing wheel is always in braking state. After having turned to, under the effect of back-moving spring, make the first pressure-gradient control valve spool return, the pressure oil instantaneous recovery of propons is connected, and after this, front-rear axle is braking simultaneously just.
The oil circuit control of the first pressure-gradient control valve in the present invention (V mouth pressure) comes from the first shuttle valve; The output pressure of the first shuttle valve comes from the controlled pressure of amplifying valve in switching valve, and while only turning to, the first shuttle valve just has and can realize the elevated pressures output preferentially turning to, otherwise output pressure is very little, cannot cut off the brake circuit of front driving axle; The output pressure of the first shuttle valve must could be controlled the first pressure-gradient control valve through hydraulic control one-way valve; The unlatching of hydraulic control one-way valve is controlled by foot brake valves, i.e. brake is opened, otherwise can close; The attainable function of above feature is: while brake, hydraulic control one-way valve is closed, and steering cannot exert an influence to brakes; When brake, if do not turned to, although hydraulic control one-way valve is opened, the output pressure of the first shuttle valve is very little, and the V mouth pressure of the first pressure-gradient control valve cannot overcome the active force of its back-moving spring, therefore cannot cut off the brake circuit of front driving axle; Only, after brake, when steering work, whole skid steer system just can realize propons braking and removes and turn to.
Advantage of the present invention:
1. cost advantage is obvious. Whole skid steer system has possessed braking and the turning function of engineering machinery normal need, just need the extra cost that increases the first pressure-gradient control valve, the first shuttle valve, hydraulic control one-way valve and associated pipe, the cost compare hundreds thousand of with engineering machinery, the cost of increase is very little.
2. it is very high that the control of hydraulic oil makes the sensitivity of whole system. After brake, hydraulic control one-way valve is opened rapidly, as long as a dozen turn to, the outlet pressure of the first shuttle valve is just delivered to rapidly the control port of the first pressure-gradient control valve, and the spool of the first pressure-gradient control valve is commutated fast, thereby the brake pressure of releasing front driving axle turns to realize; Turn to after end, the spool of the first pressure-gradient control valve Rapid reset again, recovers the braking of brakes to front driving axle. The control of hydraulic oil is quick on the draw whole system.
3. the principle of whole skid steer system is simple, easily understands, and breaks down than being easier to judgement, and attendant keeps in repair easy to detect, and maintenance cost is lower, once break down, can get rid of fast.
4. after brake, complete machine has steering capability completely, has improved the security of complete machine. Common engineering machinery does not have the normal direction of rotation function of complete machine after brake locking tire. The in the situation that the present invention having realized complete machine in needs braking and has turned to; carry out avoiding obstacles with the fastest speed and the shortest braking distance; complete machine still has steering capability completely during by locking at tire; thereby can ensure the direction to control ability of driver to complete machine, protection driver's life security. Safe in common engineering machinery.
5. the further perfect design specification of engineering machinery about traditional four-wheel braking, has increased security and the adaptive capacity of complete machine. Engineering machinery, in order fully effectively to utilize complete machine weight to carry out increasing traction, all adopts four-wheel drive, and has the place of driving just to have braking, therefore all adopts four-wheel braking. The present invention can be in the situation that propons need to be braked and turn to, and first turn to then braking, and trailing wheel keeps on-position always, and " front-wheel steer, trailing wheel are braked " carries out simultaneously, and this engineering machinery field in four-wheel drive belongs to a large innovative point.
6. skid steer system suitability of the present invention is extensive. Carry out " point is stopped " and braking with locked wheels in smooth-riding surface and carry out in complex road surface operating mode " point is stopped " when braking, complete machine still has propons and first turns to the ability of rear braking. Realized braking to turning to not impact, common car does not have.
7. the manufacturing technology maturation of the basic liquid pressure valve such as pressure-gradient control valve, shuttle valve, hydraulic control one-way valve, easy to process, be easily embodied as the supporting application of complete machine. Can easily be used in practice the vitality that has determined any patent of invention, domestic had a ripe basic liquid pressure valve manufacturing technology, in a lot of engineering machinery, realize specific function with pressure-gradient control valve, shuttle valve, hydraulic control one-way valve etc., therefore, engineering machinery skid steer system of the present invention is easy to realize application in engineering machinery.
8. can alleviate the wearing and tearing of front axle tyre, because propons has been removed brake pressure temporarily, front-wheel can Free-rolling, therefore when descending turns to, the state that front-wheel rolls in one side turn away, compared with the tire of pure sliding motion, the wearing and tearing that alleviated tire, have extended service life of front axle tyre.
9. this system is easy to be applied. Whole system because basic liquid pressure valve is easy to process, the extra cost increasing of system is very little, security is than common Che Genggao, fault easily judges, the sensitivity of system is very high, and adaptability is very extensive, makes this system easily be promoted and adopt.
10. choke valve can be replaced by adjustable throttling, changes the flow by cooler, to adapt to the requirement of different type of machines, different operating modes by the size that changes restriction.
Brief description of the drawings
Fig. 1 is schematic diagram of the present invention;
Fig. 2 is the schematic diagram of switching valve in Fig. 1;
Fig. 3 is rear each spool work sheet of right turn of brake;
Fig. 4 is rear each spool work sheet of left steering of brake;
In figure: 1, left steering cylinder; 2, right steering cylinder; 3, switching valve; 4, propons accumulator; 5, back axle accumulator; 6, foot brake valves; 7, pressure switch; 8, hydraulic control one-way valve; 9, rear driving axle; 10, front driving axle; 11, the first pressure-gradient control valve; 12, fuel tank; 13, fine filter; 14, coarse filter; 15, choke valve; 16, cooler; 17, the first pump; 18, the second pump; 19, the first overflow valve; 20, steering gear; 21, right limit valve; 22, the first shuttle valve; 23, left limit valve; 24, the second shuttle valve; 25, amplifying valve; 26, the second pressure-gradient control valve; 27, the second overflow valve.
Detailed description of the invention
Be below a specific embodiment of the present invention, existing the invention will be further described by reference to the accompanying drawings.
As depicted in figs. 1 and 2, it comprises left steering cylinder 1, right steering cylinder 2, switching valve 3, foot brake valves 6, rear driving axle 9, front driving axle 10, steering gear 20 and fuel tank 12; Switching valve 3 comprises the second shuttle valve 24, amplifying valve 25, the second pressure-gradient control valve 26 and the second overflow valve 27.
The loculus outlet of left steering cylinder 1 exports with the large chamber of right steering cylinder 2 the B mouth that simultaneously connects the second shuttle valve 24 in switching valve 3, and the large chamber outlet of left steering cylinder 1 and the loculus outlet of right steering cylinder 2 connect the A mouth of the second shuttle valve 24 in switching valve 3 simultaneously; In switching valve 3, the L2 mouth of amplifying valve 25 connects the L1 mouth of left limit valve 23, and in switching valve 3, the R2 mouth of amplifying valve 25 connects the R1 mouth of right limit valve 21; The D mouth of switching valve 3 connects the entrance of choke valve 15, and the E mouth of switching valve 3 connects the outlet of the second pump 18, and the N mouth of switching valve 3 is access to other system.
The P1 mouth of the G Kou Yi road pin brake valve 6 of propons accumulator 4, other system is accessed on another road of its G mouth; The P2 mouth of the H Kou Yi road pin brake valve 6 of back axle accumulator 5, other system is accessed on another road of its H mouth; The K1 mouth of foot brake valves 6 connects the P3 mouth of the first pressure-gradient control valve 11, the K3 mouth of the first pressure-gradient control valve 11 connects the entrance of the brake piping of front driving axle 10, the K2 mouth of foot brake valves 6 connects the entrance of the brake piping of rear driving axle 9, and the T3 mouth of T1 mouth, T2 mouth and first pressure-gradient control valve 11 of foot brake valves 6 connects the entrance of choke valve 15 simultaneously; The second tunnel of the K2 mouth of foot brake valves 6 connects the U mouth of hydraulic control one-way valve 8, and the Third Road of the K2 mouth of foot brake valves 6 connects the entrance of pressure switch 7. The B2 mouth of hydraulic control one-way valve 8 connects the V mouth of the first pressure-gradient control valve 11, and the A2 mouth of hydraulic control one-way valve 8 connects the oil-out of the first shuttle valve 22.
The L0 mouth of left limit valve 23 connects the L mouth of steering gear 20, and the R0 mouth of right limit valve 21 connects the R mouth of steering gear 20; The oil return opening of the T4 mouth connected tank 12 of steering gear 20, the P4 mouth of steering gear 20 connects the Y mouth of the first pump 17, another road of Y mouth of the first pump 17 connects the entrance of the first overflow valve 19, the outlet of the first overflow valve 19 connects the entrance of choke valve 15, another road of the outlet of the first overflow valve 19 connects the entrance of cooler 16, the outlet of the outlet of cooler 16 and choke valve 15 connects the entrance of fine filter 13 simultaneously, the oil return opening of the outlet connected tank 12 of fine filter 13.
The entrance of the entrance of the first pump 17 and the second pump 18 connects the outlet of coarse filter 14 simultaneously, the oil-out of the entrance connected tank 12 of coarse filter 14. The L1 mouth of the A1 mouth access left limit valve 23 of the first shuttle valve 22, the R1 mouth of the B1 mouth access right limit valve 21 of the first shuttle valve 22.
When driver steps on after brake pedal, the P1 mouth of foot brake valves 6 and K1 mouth are connected, P2 mouth and K2 mouth are connected, the pressure oil of propons accumulator 4 is gone to front driving axle 10 through G mouth, P1 mouth, K1 mouth, the P3 mouth of the first pressure-gradient control valve 11, K3 mouth, rear driving axle 9 is gone to through H mouth, P2 mouth, K2 mouth in pressure oil one tunnel of back axle accumulator 5, hydraulic control one-way valve 8 is gone on another road, and hydraulic control one-way valve 8 is opened, and A2 mouth, B2 mouth are connected. Front driving axle 10, rear driving axle 9 be braking simultaneously just, and front and back wheel is by locking completely. The now oriented right turn of complete machine and turning left to two kinds of situations.
The first situation right turn
As shown in Figure 3, driver's steering wheel that turns right, the P4 mouth of steering gear 20 and R mouth are connected, T4 mouth and L mouth are connected, the hydraulic oil of fuel tank 12 is under the effect of the first pump 17, through the P4 mouth of coarse filter 14, the first pump 17, steering gear 20, R mouth enters into switching valve 3 amplifying valves 25 again R2 mouth through the R0 of right limit valve 21 mouth, R1 mouth, due to the pressure of R2 mouth be greater than L2 mouth (with fuel tank 12 cut-in pressures be 0), the spool that control-oil pressure overcomes the back-moving spring promotion amplifying valve 25 of amplifying valve 25 moves to right, now:
Yi mono-tunnel: oil circuit control oil return, the spool of amplifying valve 25 moves to right and makes pressure oil get back to fuel tank 12 through L mouth, the T4 mouth of L1 mouth, L0 mouth and the steering gear 20 of the L2 of amplifying valve 25 mouth, left limit valve 23, realizes the oil return of oil circuit control.
Yi bis-tunnels: the A mouth of switching valve 3 and C mouth are connected, B mouth connect with D mouth (with fuel tank 12 cut-in pressures be 0 substantially), because A mouth pressure is higher than B mouth pressure, now the second shuttle valve 24 is opened, A mouth and the connection of F mouth; Now, the F mouth pressure of the second pressure-gradient control valve 26 and the pressure sum of its back-moving spring are greater than the pressure of C mouth, and therefore the spool of the second pressure-gradient control valve 26 moves right, until E mouth and A mouth are connected completely.
Yi tri-tunnels: due to the R2 mouth of switching valve 3 and the connection of the B1 mouth of the first shuttle valve 22, the A1 mouth of the L2 mouth of switching valve 3 and the first shuttle valve 22 is connected, and the pressure of B1 mouth is greater than the pressure of A1 mouth. Therefore, the first shuttle valve 22 is opened, pressure oil arrives the V mouth of the first pressure-gradient control valve 11 through B1 mouth, the A2 mouth of hydraulic control one-way valve 8, the B2 mouth of the first shuttle valve 22, the V mouth pressure of the first pressure-gradient control valve 11 is greater than the active force of its back-moving spring, therefore on the spool of the first pressure-gradient control valve 11, move, P3 mouth and K3 mouth disconnect, K3 mouth and T3 mouth are connected, the pressure oil of front driving axle 10 is through K3 mouth, the T3 mouth of the first pressure-gradient control valve 11 for this reason, arrive fine filter 13 through cooler 16 and choke valve 15 respectively again, return to after filtering fuel tank 12. Realize the release of front driving axle 10, now the tire of front driving axle 10 can be realized Free-rolling.
The A mouth of switching valve 3 communicates with the loculus of the large chamber of left steering cylinder 1 and right steering cylinder 2, the large chamber of the B mouth of switching valve 3 and the loculus of left steering cylinder 1 and right steering cylinder 2 is connected, and hydraulic oil is gone to the large chamber of left steering cylinder 1 and the loculus of right steering cylinder 2 through fuel tank 12, coarse filter 14, the second pump 18, the E mouth of switching valve 3, amplifying valve 25, A mouth under the effect of the second pump 18; And the fluid in the large chamber of the loculus of left steering cylinder 1 and right steering cylinder 2 is through the B of switching valve 3 mouth, amplifying valve 25, D mouth, arrive fine filter 13 through cooler 16 and choke valve 15 respectively again, return to after filtering fuel tank 12, front driving axle 10 is realized and being turned right normally under the acting in conjunction of left steering cylinder 1, right steering cylinder 2 for this reason.
Work sheet when the rear right turn of brake after spool commutation is as Fig. 3.
When driver turns right according to operating mode after end, when steering wheel no longer rotates, the P4 mouth of steering gear 20 and R mouth disconnect, T4 mouth and L mouth disconnect, although the oil circuit control at amplifying valve 25 two ends is full of pipeline, and the instantaneous reduction of pressure, and the whereabouts of oil circuit is cut off, now the spool of amplifying valve 25 is retracted position in the pressure bottom left of its back-moving spring, and moving to left of spool makes the pressure of L2 mouth occur negative pressure, needs repairing; And the pressure of R2 mouth increases, need to extrude unnecessary oil, the fluid that increases the R2 mouth of pressure carries out repairing through the throttling control port of amplifying valve 25 to the L2 mouth that occurs negative pressure, and the oil that R2 mouth is extruded enters and needs the L2 of repairing mouth through restriction, accurately gets back to meta thereby realize spool. Left steering cylinder 1 and right steering cylinder 2 quit work, and tyre rotation stops, and car load is turned right to end.
After the valve core reset of amplifying valve 25, the A mouth of switching valve 3 and E mouth and C mouth disconnect, B mouth and D mouth disconnect, because the pressure of E mouth constantly raises under the effect of the second pump 18, therefore the pressure of C mouth constantly becomes large, until the pressure of C mouth is while being greater than the pressure sum of F mouth pressure and the second pressure-gradient control valve 26 back-moving springs, the spool of the second pressure-gradient control valve 26 is just moved to the left, because the spool displacement amount of the second pressure-gradient control valve 26 is very little, the pressure oil of F mouth just has micro-fluid by laying down in whole system, until the E mouth of switching valve 3 and N mouth are connected completely, from the pressure oil of the second pump 18 through the E of switching valve 3 mouth, N mouth is gone to other system.
When the spool of amplifying valve 25 is got back to after meta, the existing pressure balance of R2 mouth and L2 cause for gossip, R2 mouth with turn right to time pressure compared with, pressure decreased. The V mouth equipressure of the R2 mouth of amplifying valve 25 and the first pressure-gradient control valve 11, in the time that steering wheel stops operating, the V mouth pressure of the first pressure-gradient control valve 11 is synchronizeed instantaneous reduction with the R2 mouth pressure of amplifying valve 25, V mouth pressure has been less than the active force of the first pressure-gradient control valve 11 back-moving springs, under the effect of the first pressure-gradient control valve 11 back-moving springs, the spool of the first pressure-gradient control valve 11 moves down, and P3 mouth and K3 mouth are connected, and K3 mouth and T3 mouth disconnect. Therefore, the pressure oil of propons accumulator 4 is gone to front driving axle 10 through G mouth, P1 mouth, K1 mouth, the P3 mouth of the first pressure-gradient control valve 11, K3 mouth, and the pressure oil of front driving axle 10 recovers to connect, and recovers the state being braked. And in whole steering procedure, rear driving axle 9 keeps on-position always.
So far completed complete machine under on-position, turn right to function.
The second situation left steering
As shown in Figure 4, driver's steering wheel that turns left, the P4 mouth of steering gear 20 and L mouth are connected, T4 mouth and R mouth are connected, under the effect of the first pump 17, pressure oil is through the P4 mouth of fuel tank 12, coarse filter 14, the first pump 17, steering gear 20, L mouth enters into switching valve 3 amplifying valves 25 again L2 mouth through the L0 of left limit valve 23 mouth, L1 mouth, and the spool of amplifying valve 25 overcomes its back-moving spring and is moved to the left under the oil pressure of L2 mouth, now:
Er mono-tunnel: the fluid of the R2 mouth of amplifying valve 25 returns to fuel tank 12 through R mouth, the T4 mouth of the R1 of right limit valve 21 mouth, R0 mouth, steering gear 20, realizes the oil return of oil circuit control.
Er bis-tunnels: the spool of amplifying valve 25 moves to left the B mouth of switching valve 3 and C mouth are connected, A mouth and D mouth connect (with fuel tank 12 cut-in pressures be 0 substantially), because B mouth pressure is higher than A mouth pressure, the second shuttle valve 24 is opened, B mouth and F mouth are connected, and the pressure sum of F mouth pressure now and the second pressure-gradient control valve 26 back-moving springs is greater than the pressure of C mouth, and therefore the spool of the second pressure-gradient control valve 26 moves right, until E mouth and N mouth disconnect completely, E mouth and B mouth are connected completely.
Er tri-tunnels: the L2 mouth pressure of switching valve 3 is higher than R2 mouth pressure, the A1 mouth of the L2 mouth of switching valve 3 and the first shuttle valve 22 is connected, the B1 mouth of the R2 mouth of switching valve 3 and the first shuttle valve 22 is connected, therefore the first shuttle valve 22 is opened, pressure oil is through the A1 mouth of the first shuttle valve 22, the A2 mouth of hydraulic control one-way valve 8, B2 mouth arrives the V mouth of the first pressure-gradient control valve 11, the V mouth pressure of the first pressure-gradient control valve 11 is greater than the active force of its back-moving spring, therefore on the spool of the first pressure-gradient control valve 11, move, P3 mouth and K3 mouth disconnect, K3 mouth and T3 mouth are connected, the pressure oil of front driving axle 10 is through the K3 mouth of the first pressure-gradient control valve 11 for this reason, T3 mouth, arrive fine filter 13 through cooler 16 and choke valve 15 respectively again, return to after filtering fuel tank 12. realize the release of front driving axle 10, the tire of front driving axle 10 can be realized Free-rolling.
Hydraulic oil is gone to the large chamber of loculus and the right steering cylinder 2 of left steering cylinder 1 under the effect of the second pump 18 through fuel tank 12, coarse filter 14, the second pump 18, the E mouth of switching valve 3, amplifying valve 25, B mouth; And the fluid of the large chamber of left steering cylinder 1 and the loculus of right steering cylinder 2 is through the A of switching valve 3 mouth, amplifying valve 25, D mouth, then arrive fine filter 13 through cooler 16 and choke valve 15 respectively, return to after filtering fuel tank 12. Front driving axle 10 is realized and being turned left normally under the acting in conjunction of left steering cylinder 1, right steering cylinder 2 for this reason.
Work sheet when the rear left steering of brake after spool commutation is as Fig. 4.
When complete machine is turned left after end, when steering wheel no longer rotates, the P4 mouth of steering gear 20 and L mouth disconnect, T4 mouth and R mouth disconnect, although the oil circuit control at amplifying valve 25 two ends is full of pipeline, instantaneous pressure reduces, and the whereabouts of oil circuit is cut off, the now spool of amplifying valve 25 return to the right under the pressure of its back-moving spring, moving to right of spool makes the pressure of R2 mouth occur negative pressure, needs repairing; And the pressure of L2 mouth increases, need to extrude unnecessary oil, the fluid that increases the L2 mouth of pressure carries out repairing through the throttling control port of amplifying valve 25 to the R2 mouth that occurs negative pressure, and the oil that L2 mouth is extruded enters and needs the R2 of repairing mouth through restriction, thereby realizes the parking position accuracy of spool. Left steering cylinder 1 and right steering cylinder 2 quit work, and tyre rotation stops, and car load is turned left to end.
After the valve core reset of amplifying valve 25, the B mouth of switching valve 3 and E mouth and C mouth disconnect, A mouth and D mouth disconnect, because the pressure of E mouth constantly raises under the effect of the second pump 18, therefore the pressure of C mouth constantly becomes large, until the pressure of C mouth is while being greater than the pressure sum of F mouth pressure and the second pressure-gradient control valve 26 back-moving springs, the spool of the second pressure-gradient control valve 26 is just moved to the left, because the spool displacement amount of the second pressure-gradient control valve 26 is very little, the pressure oil of F mouth just has micro-fluid by laying down in whole system, until the E mouth of switching valve 3 and N mouth are connected completely, from the pressure oil of the second pump 18 through the E of switching valve 3 mouth, N mouth is gone to other system.
When the spool of amplifying valve 25 is got back to after meta, the existing pressure balance of L2 mouth and R2 cause for gossip, L2 mouth with turn left to time pressure compared with, pressure decreased. The V mouth equipressure of the L2 mouth of amplifying valve 25 and the first pressure-gradient control valve 11, in the time that steering wheel stops operating, the V mouth pressure of the first pressure-gradient control valve 11 is synchronizeed instantaneous reduction with the L2 mouth pressure of amplifying valve 25, V mouth pressure has been less than the active force of the first pressure-gradient control valve 11 back-moving springs, under the effect of the first pressure-gradient control valve 11 back-moving springs, the spool of the first pressure-gradient control valve 11 moves down, and P3 mouth and K3 mouth are connected, and K3 mouth and T3 mouth disconnect. Therefore, the pressure oil of propons accumulator 4 is gone to front driving axle 10 through G mouth, P1 mouth, K1 mouth, the P3 mouth of the first pressure-gradient control valve 11, K3 mouth, and the pressure oil of front driving axle 10 recovers again to connect, and continues the state that maintenance is braked. And in whole steering procedure, rear driving axle 9 keeps on-position always.
So far completed complete machine under on-position, turn left to function.
Above two kinds of situations, complete machine has retained normal turning function completely.
After driver loosens the brake, foot brake valves 6 is Rapid reset under the effect of its back-moving spring, the K1 mouth of foot brake valves 6 and T1 mouth are connected, K2 mouth and T2 mouth are connected, the brake pressure oil of front driving axle 10 is through K3 mouth, P3 mouth, the K1 mouth of foot brake valves 6, the T1 mouth of the first pressure-gradient control valve 11, arrive fine filter 13 through cooler 16 and choke valve 15 respectively again, return to after filtering fuel tank 12; The brake pressure oil of rear driving axle 9 is through the K2 of foot brake valves 6 mouth, T2 mouth, then arrives fine filter 13 through cooler 16 and choke valve 15 respectively, returns to after filtering fuel tank 12. Now, the U mouth pressure of hydraulic control one-way valve 8 is 0 substantially, and therefore, hydraulic control one-way valve 8 is closed, and B2 mouth and A2 mouth disconnect. Thereby realize complete skid steer process.
After brake finishes, the work sheet of each spool is as Fig. 1.
Suppose to occur another kind of situation: driver steps on after brake, turn to again, the work of each valve is described above, do not finish if also turned to, and driver is because brake pedal has been unclamped in misoperation, now, the spool returning quickly of foot brake valves 6, the U mouth pressure of hydraulic control one-way valve 8 is 0 substantially, therefore, hydraulic control one-way valve 8 is closed, A2 mouth and B2 mouth disconnect, because remaining hydraulic control one-way valve 8, the V mouth pressure of the first pressure-gradient control valve 11 closes previous A2 mouth pressure, therefore the still position after above moving of the spool of the first pressure-gradient control valve 11, be that K3 mouth and T3 mouth are connected, the pressure oil of front driving axle 10 is by the K3 mouth of the first pressure-gradient control valve 11, T3 mouth carries out release, turn to and can normally carry out, and turn to after end, the A2 mouth pressure of hydraulic control one-way valve 8 reduces, and B2 mouth pressure is higher than A2 mouth pressure, and hydraulic control one-way valve 8 is opened, and the V mouth pressure of the first pressure-gradient control valve 11 starts to reduce. therefore, the first pressure-gradient control valve 11 promotes spool and moves down under the effect of its back-moving spring, makes K3 mouth connect P3 mouth, and the pressure oil of front driving axle 10 carries out release by K3 mouth, P3 mouth, the K1 mouth of foot brake valves 6, the T1 mouth of the first pressure-gradient control valve 11. therefore the situation of this " misoperation " does not affect the release of normally carrying out of turning to and front driving axle 10.
In short time, continuous several times is stepped on after brake pedal, and the pressure of the G mouth of propons accumulator 4, the H mouth of back axle accumulator 5 can reduce, and the topping up of propons accumulator 4, back axle accumulator 5 is completed by other system to recover its rated pressure.
The effect of pressure switch 7 is " low pressure alarmings ", when to the brake pressure of drive axle lower than set value time, pressure switch connect, complete machine just start report to the police, to point out driver's brake pressure too low.
The function of hydraulic control one-way valve 8: only, in the time of braking, hydraulic control one-way valve 8 is just opened, ensures that the controlled pressure of steering can be controlled the first pressure-gradient control valve 11; And while not braking, hydraulic control one-way valve 8 is closed, steering does not produce any impact to brakes.
The effect of choke valve 15 is, ensures in oil return line that some hydraulic oil must be through subcooler 16, and hydraulic oil is carried out after cooling returning to fuel tank 12 again.
The function of the first overflow valve 19: in the time that the Y mouth pressure of the first pump 17 is elevated to its rated pressure; the first overflow valve 19 is opened, and hydraulic oil is through the first overflow valve 19, then arrives fine filter 13 through cooler 16 and choke valve 15 respectively; return to again fuel tank 12, the Hydraulic Elements in protection oil circuit.
The function of right limit valve 21 is: when complete machine turn right to time, RO mouth pressure is higher than R1 mouth, in the time that right turn arrives extreme position, the gag lever post of right limit valve 21 is touched, gag lever post drives the commutation that moves right of the spool of right limit valve 21, thereby cut off RO mouth, the R1 mouth of right limit valve 21, turned right to termination. Now when complete machine turn left to time, the oil circuit control of the R2 mouth of switching valve 3 is opened the check valve of right limit valve 21 through the R1 of right limit valve 21 mouth, pass through again the oil return of R0 mouth, when complete machine is turned left after very little angle, avoid behind limit on the right-right-hand limit position, the gag lever post of right limit valve 21 unclamps, and the back-moving spring of right limit valve 21 promotes the spool commutation that moves to left, and fluid returns to fuel tank 12 through R1 mouth, R0 mouth.
The functional equivalent of left limit valve 23 is in right limit valve 21.
The function of the second overflow valve 27 is: in the time that switching valve 3 is elevated to rated pressure towards the pressure of steering cylinder; the second overflow valve 27 is opened; hydraulic oil is through the D mouth of the second overflow valve 27, switching valve 3; arrive fine filter 13 through cooler 16 and choke valve 15 respectively again; return to again fuel tank 12, the Hydraulic Elements in protection oil circuit.
When whole system does not touch on the brake, brakes does not produce any impact to steering, and steering does not produce any impact to brakes yet. When not touching on the brake, the U mouth pressure of hydraulic control one-way valve 8 is 0 substantially, and therefore, hydraulic control one-way valve 8 is closed. The oil circuit control of steering can only arrive the A2 mouth of hydraulic control one-way valve 8, cannot arrive B2 mouth, and therefore the first pressure-gradient control valve 11 is equivalent to the sebific duct of connecting, and steering does not affect brakes. The overall performance of this " skid steer system " is identical with not having.
And step on while brake, after brakes generation effect, the effect of this system is in the time that propons needs braking simultaneously and turns to, and preferentially turns to, and then braking. Allow steering exert an influence to brakes, preferentially turn to thereby realize, turn to after end, propons continues to keep on-position.
Claims (5)
1. an engineering machinery skid steer system, comprises left steering cylinder (1), right steering cylinder (2), switching valve (3), foot brake valves (6), rear driving axle (9), front driving axle (10), steering gear (20) and fuel tank (12);
Described left steering cylinder (1) is connected with switching valve (3) with right steering cylinder (2); E mouth on switching valve (3) is connected with the second pump (18), and the D mouth of switching valve (3) is connected to fuel tank (12);
The L mouth of described steering gear (20) and R mouth are connected to switching valve (3), and the T4 mouth of steering gear (20) connects fuel tank (12), and the P4 mouth of steering gear (20) is connected with respectively the first pump (17) and the first overflow valve (19); Described the first overflow valve (19) other end is connected to fuel tank (12);
The P1 mouth of described foot brake valves (6) is connected with propons accumulator (4), and the K1 mouth of foot brake valves (6) is connected to front driving axle (10); The P2 mouth of described foot brake valves (6) is connected with back axle accumulator (5), and the K2 mouth of foot brake valves (6) is connected to rear driving axle (9); The T1 of foot brake valves (6), T2 mouth are connected to fuel tank (12);
It is characterized in that:
K1 mouth at described foot brake valves (6) is provided with first pressure-gradient control valve (11) to the oil circuit of front driving axle (10); Described the first pressure-gradient control valve (11) is a hydraulic control two-bit triplet reversal valve, and the upper P3 of the being mouth of the first pressure-gradient control valve (11) is communicated with K3 mouth, its next T3 of being mouth is communicated with K3 mouth; The P3 mouth of the first pressure-gradient control valve (11) is connected with the K1 mouth of foot brake valves (6), and the K3 mouth of the first pressure-gradient control valve (11) is connected to front driving axle (10), and the T3 mouth of the first pressure-gradient control valve (11) is connected to fuel tank (12); The upper control chamber of the first pressure-gradient control valve (11) is provided with back-moving spring;
Between described steering gear (20) L mouth and the outlet oil circuit of R mouth, be connected with the first shuttle valve (22), the oil-out of the first shuttle valve (22) is connected with hydraulic control one-way valve (8); The A2 mouth of described hydraulic control one-way valve (8) connects the oil-out of the first shuttle valve (22), and the B2 mouth of hydraulic control one-way valve (8) connects the V mouth of control chamber under the first pressure-gradient control valve (11), the K2 mouth of the U mouth pin brake valve (6) of hydraulic control one-way valve (8).
2. a kind of engineering machinery skid steer system according to claim 1, is characterized in that: in described foot brake valves (6) K2 mouth is connected to the oil circuit of rear driving axle (9), be provided with pressure switch (7).
3. a kind of engineering machinery skid steer system according to claim 1, is characterized in that: the T1 of described the first overflow valve (19), the D mouth of switching valve (3), foot brake valves (6) and the T3 mouth of T2 mouth and the first pressure-gradient control valve (11) are connected to fuel tank (12) by a fine filter (13).
4. a kind of engineering machinery skid steer system according to claim 3, is characterized in that: in the oil circuit at described fine filter (13) oil-in place, be connected with the choke valve (15) and the cooler (16) that are connected in parallel.
5. a kind of engineering machinery skid steer system according to claim 1, is characterized in that: described the first pump (17) and the oil-in of the second pump (18) are connected to fuel tank (12) by a coarse filter (14).
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| Application Number | Priority Date | Filing Date | Title |
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| CN201410289775.5A CN104071219B (en) | 2014-06-25 | 2014-06-25 | A kind of engineering machinery skid steer system |
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| CN201410289775.5A CN104071219B (en) | 2014-06-25 | 2014-06-25 | A kind of engineering machinery skid steer system |
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| CN104071219B true CN104071219B (en) | 2016-05-25 |
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| GB2572393A (en) * | 2018-03-28 | 2019-10-02 | Caterpillar Inc | Hydraulic system for a machine |
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| US5927072A (en) * | 1997-04-24 | 1999-07-27 | Caterpillar Inc. | Load sense hydraulic system |
| DE10109351A1 (en) * | 2000-02-28 | 2001-10-11 | Toyoda Automatic Loom Works | Hydraulic device for industrial vehicles |
| GB2426800A (en) * | 2005-05-31 | 2006-12-06 | Linde Ag | Working machine with an hydraulic pump connected to the steering, brakes and working hydraulics |
| CN201923203U (en) * | 2010-12-01 | 2011-08-10 | 泸州长起特种起重设备有限公司 | Hydraulic steering and brake circuit for two-bridge engineering machinery |
| CN203651883U (en) * | 2013-10-28 | 2014-06-18 | 龙工(上海)机械制造有限公司 | Wheel-type loader hydraulic system with emergency steering function |
| CN203920888U (en) * | 2014-06-25 | 2014-11-05 | 徐工集团工程机械股份有限公司 | A kind of construction machinery and equipment skid steer system |
-
2014
- 2014-06-25 CN CN201410289775.5A patent/CN104071219B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5927072A (en) * | 1997-04-24 | 1999-07-27 | Caterpillar Inc. | Load sense hydraulic system |
| DE10109351A1 (en) * | 2000-02-28 | 2001-10-11 | Toyoda Automatic Loom Works | Hydraulic device for industrial vehicles |
| GB2426800A (en) * | 2005-05-31 | 2006-12-06 | Linde Ag | Working machine with an hydraulic pump connected to the steering, brakes and working hydraulics |
| CN201923203U (en) * | 2010-12-01 | 2011-08-10 | 泸州长起特种起重设备有限公司 | Hydraulic steering and brake circuit for two-bridge engineering machinery |
| CN203651883U (en) * | 2013-10-28 | 2014-06-18 | 龙工(上海)机械制造有限公司 | Wheel-type loader hydraulic system with emergency steering function |
| CN203920888U (en) * | 2014-06-25 | 2014-11-05 | 徐工集团工程机械股份有限公司 | A kind of construction machinery and equipment skid steer system |
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| CN104071219A (en) | 2014-10-01 |
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