CN103388600A - Aloft work engineering machine and servo hydraulic system thereof - Google Patents

Abstract

The invention discloses an aloft work engineering machine and a servo hydraulic system thereof. The servo hydraulic system comprises a hydraulic oil cylinder and a servo valve for controlling the hydraulic oil cylinder to be retracted; the servo valve is provided with a first throttling window and a second throttling window, which respectively correspond to a rodless cavity and a rod cavity of the hydraulic oil cylinder; and an area gradient ratio of the first throttling window to the second throttling window is equal to an effective area ratio of the rodless cavity to the rod cavity. The servo hydraulic system disclosed by the invention provides one asymmetric servo valve; when a piston rod of the hydraulic oil cylinder is stretched out or retracted back, the pressure difference between the rodless cavity and the rod cavity is zero, namely a phenomenon that the pressure of the two cavities is suddenly changed when a movement direction of the piston rod in the background technology is changed is eliminated, so that the working of the hydraulic oil cylinder is more stable. When the servo hydraulic system disclosed by the invention is applied to leveling a working platform, the stability, accuracy and rapidness of leveling the working platform can be ensured, and the leveling precision is improved.

Description

High-altitude operation engineering machinery and servo hydraulic system thereof

Technical field

The present invention relates to technical field of engineering machinery, particularly a kind of high-altitude operation engineering machinery and servo hydraulic system thereof.

Background technique

Hydraulic jack is the common parts in hydraulic system, and the flexible of hydraulic jack can drive load variations, and to adapt to different operating mode demands, the flexible of hydraulic jack generally can be by servo valve control.Take the working platform of high-altitude operation engineering machinery as example, the flexible levelling working platform of hydraulic jack.

Please refer to Fig. 1, Fig. 1 is a kind of structure diagram of typical servo hydraulic system.

Pressure is the lumen that the hydraulic oil of P is communicated with servovalve 12, and the chamber at two ends is communicated with fuel tank, and pressure is T, and two actuator ports of servovalve 12 are communicated with respectively rod chamber and the rodless cavity of hydraulic jack 11.When the spool 123 of servovalve 12 moves, can change the connected state of two actuator ports and in-line or oil circuit.Servovalve 12 is symplex structure, its two actuator port and the two equal symmetric designs of valve piece, and the first actuator port 121 as shown in Figure 1, the second actuator port 122, and the first valve piece 123a, second valve piece 123b, structure is all identical.

Spool 123 is when middle lt, and two valve pieces of spool 123 move to left simultaneously, and the first actuator port 121 that is communicated with rodless cavity is communicated with lumen, i.e. rodless cavity oil-feed; The second actuator port 122 that is communicated with rod chamber is communicated with the right-hand member chamber, i.e. rod chamber oil return, and piston rod 111 stretches out, as shown in Figure 1;

Spool 123 is when middle gt, and two valve pieces of spool 123 move to right simultaneously, and the first actuator port 121 that is communicated with rodless cavity is communicated with the left end chamber, i.e. rodless cavity oil return; The second actuator port 122 that is communicated with rod chamber is communicated with middle chamber, i.e. rod chamber oil-feed, and piston rod 111 is retracted;

When spool 123 was in meta, two valve pieces of spool 123 were blocked two actuator ports, and rod chamber, rodless cavity and in-line, oil circuit all disconnect, thereby make hydraulic jack 11 remain on current state.

During hydraulic jack 11 leveling working platform, be that working platform is the load 13 of hydraulic jack 11, piston rod 111 stretches out or while retracting, can drive working platform makes progress or rotates in vertical plane,, according to the heeling condition of working platform, can stretch out or retract by the piston rod 111 that servovalve 12 is controlled hydraulic jack 11.

At present, when the leveling working platform, find to exist following technical problem:

Working platform is in the leveling process, when upwards rotating again or upwards rotating again downwards, be that hydraulic jack 11 piston rod 111 moving direction are while changing, can there be pressure jump in the pressure in 11 liang of chambeies of hydraulic jack, cause hydraulic jack 11 job insecurities, during specific to working platform, affect stability, accuracy and the rapidity of working platform leveling, namely affected the leveling precision.

In view of this, how to improve servo hydraulic system, while to eliminate hydraulic cylinder piston rod moving direction, changing, two cavity pressures produce the phenomenon of sudden change, are the technical problems that those skilled in the art need to be resolved hurrily.

Summary of the invention

For solving the problems of the technologies described above, purpose of the present invention is for a kind of high-altitude operation engineering machinery and servo hydraulic system thereof are provided, and when this servo hydraulic system can be eliminated the change of hydraulic cylinder piston rod moving direction, two cavity pressures produce the phenomenon of sudden change.

Servo hydraulic system provided by the invention, comprise hydraulic jack and control the flexible servovalve of described hydraulic jack, described servovalve is provided with first throttle window, the second throttling window that corresponds respectively to described hydraulic jack rodless cavity, rod chamber, the area gradient ratio of described first throttle window and described the second throttling window, with the effective active area of described rodless cavity, described rod chamber than equating.

This servo hydraulic system provides a kind of servovalve of asymmetric, when hydraulic cylinder piston rod stretches out or retracts, the pressure reduction of its rod chamber and rodless cavity is zero, namely eliminate the phenomenon of two cavity pressure sudden changes when in the background technique, the piston rod movement direction changes, made the work of hydraulic jack comparatively stable.While being applied to the working platform leveling, can guarantee stability, accuracy and the rapidity of working platform leveling, improve the leveling precision.

Preferably, the valve pocket of described servovalve is the ladder setting, and described first throttle window is located at the large footpath section of described valve pocket, and described the second throttling window is located at the path section of described valve pocket.

Preferably, described servovalve is three-position four-way valve.

The present invention also provides a kind of high-altitude operation engineering machinery, comprises the hydraulic system of working platform and the described working platform of leveling, and described hydraulic system is the described servo hydraulic system of above-mentioned any one.

Because above-mentioned servo hydraulic system has above-mentioned technique effect, the high-altitude operation engineering machinery with this hydraulic system also has identical technique effect.

Preferably, also comprise controller, and the dip sensor that detects described working platform angle of inclination; The angle signal that described controller detects according to described dip sensor is controlled described servovalve and is carried out the switching of working position.

Preferably, be specially Elevating platform fire truck.

Description of drawings

Fig. 1 is a kind of structure diagram of typical servo hydraulic system;

Fig. 2 is the structure diagram of a kind of specific embodiment of servo hydraulic system provided by the present invention;

Fig. 3 is the schematic diagram of servovalve valve pocket in Fig. 2;

Fig. 4 is the structured flowchart of a kind of specific embodiment of high-altitude operation engineering machinery leveling system provided by the present invention.

In Fig. 1:

11 hydraulic jacks, 111 piston rods, 12 servovalves, 121 first actuator ports, 122 second actuator ports, 123 spools, 123a the first valve piece, 123b second valve piece, 13 loads;

In Fig. 2-3:

21 hydraulic jacks, 211 piston rods, 22 servovalves, 221 first actuator ports, 221a first throttle window, 222 second actuator ports, 222a the second throttling window, 223 spools, 23 loads

Embodiment

In order to make those skilled in the art understand better technological scheme of the present invention, the present invention is described in further detail below in conjunction with the drawings and specific embodiments.

Please refer to Fig. 2-3, Fig. 2 is the structure diagram of a kind of specific embodiment of servo hydraulic system provided by the present invention; Fig. 3 is the schematic diagram of servovalve valve pocket in Fig. 2.

Servo hydraulic system in this embodiment, comprise hydraulic jack 21 and control the flexible servovalve 22 of hydraulic jack 21, servovalve 22 is provided with first throttle window 221a, the second throttling window 222a that corresponds respectively to hydraulic jack 21 rodless cavities, rod chamber, and the area gradient ratio of first throttle window 221a and the second throttling window 222a, with the effective active area of rodless cavity, rod chamber than equating.

But the reference background technology is understood, servovalve 22 has the first actuator port 221 and the second actuator port 222, connect respectively rodless cavity, rod chamber, when the spool 223 in servovalve 22 valve pockets moves, can change the connected state of two actuator ports and in-line, oil circuit.Servovalve 22 in Fig. 2 is three-position four-way valve, and the application area of this kind servovalve 22 is wider, and while being in meta, can make hydraulic jack 21 remain on steady state, and certainly, it is also feasible that servovalve 22 has other working positions.

To those skilled in the art, throttling window described above is valve pocket flow-passing surface corresponding to actuator port, and as shown in Figure 3, correspondingly, the area gradient of throttling window is the corresponding valve pocket girth of actuator port.Servovalve 22 in background technique is for symplex structure designs, therefore two throttling window is equal to, the area gradient ratio is 1.

And in the present embodiment, the area gradient ratio of first throttle window 221a and the second throttling window 222a, with the effective active area of rodless cavity, rod chamber than equating.The effective active area of hydraulic jack 21 rod chambers and rodless cavity, namely be positioned at the face area of the indoor piston of corresponding cavity, owing to there being piston rod 211 in rod chamber, therefore the inevitable effective active area less than rodless cavity of the effective active area of rod chamber.Therefore, the area gradient of the first throttle window 221a of the present embodiment design is greater than the area gradient of the second throttling window 222a, as shown in Figure 2, and this servovalve 22 servovalve 22 that is asymmetric.

Hereinafter will carry out analytical calculation to hydraulic jack 21 rod chambers, the pressure of rodless cavity under different operating modes, at first, the parameter and the symbol that relate to be carried out corresponding explanation:

q _V1---when piston rod 211 stretches out, flow into the flow of oil hydraulic cylinder rodless cavity;

q _V2---when piston rod 211 stretches out, the flow that the oil hydraulic cylinder rod chamber flows out;

q _V1'---when piston rod 211 is retracted, the flow that the oil hydraulic cylinder rodless cavity flows out;

q _V2'---when piston rod 211 is retracted, flow into the flow of oil hydraulic cylinder rod chamber;

w ₁---the area gradient of first throttle window 221a;

w ₂---the area gradient of the second throttling window 222a;

M---area gradient ratio, i.e. m=w ₂/ w ₁

p _s---oil supply pressure;

p ₀---return pressure, p ₀=0MPa;

A ₁---the effective active area of oil hydraulic cylinder rodless cavity;

A ₂---the effective active area of oil hydraulic cylinder rod chamber;

The effective active area ratio of n---rod chamber, rodless cavity, i.e. A ₂/ A ₁=n (0＜n＜1);

p ₁---when piston rod 211 stretches out, oil hydraulic cylinder rodless cavity pressure;

p ₂---when piston rod 211 stretches out, oil hydraulic cylinder rod chamber pressure;

p ₁'---when piston rod 211 is retracted, oil hydraulic cylinder rodless cavity pressure;

p ₂'---when piston rod 211 is retracted, oil hydraulic cylinder rod chamber pressure;

F _L---conversion is to outer load 23 power of equivalence of piston;

211 displacements of y---piston rod;

m _L---load 23 inertia are converted the equivalent mass at piston place;

x _V---spool 223 displacements.

A, when piston rod 211 stretches out, (be spool 223 displacement x _V＞0) time, by the technology general knowledge of related domain as can be known, the orifice equation of servovalve 22 first actuator ports 221, the second actuator port 222 is respectively:

${\mathrm{<figure-callout\; id="1"\; label="q\; V"\; filenames="HDA00003615156900021.png"\; state="\{\{state\}\}">q</figure-callout>}}_V=C_d{w}_1{x}_{\mathrm{<figure-callout\; id="2"\; label="V"\; filenames="HDA00003615156900021.png"\; state="\{\{state\}\}">V</figure-callout>}}\sqrt{\frac{2}{\mathrm{\&rho;}}(p_s-p_1)}---\left(1\right)$

${\mathrm{<figure-callout\; id="2"\; label="q\; V"\; filenames="HDA00003615156900021.png"\; state="\{\{state\}\}">q</figure-callout>}}_V=C_d{w}_2{x}_{\mathrm{<figure-callout\; id="2"\; label="V"\; filenames="HDA00003615156900021.png"\; state="\{\{state\}\}">V</figure-callout>}}\sqrt{\frac{2}{\mathrm{\&rho;}}{p}_2}---\left(2\right)$

C in formula _d---the valve flow coefficient;

ρ---fluid density;

By q _V1/ A ₁=q _V2/ A ₂, can obtain

$p_s={\mathrm{<figure-callout\; id="1"\; label="p"\; filenames="HDA00003615156900021.png"\; state="\{\{state\}\}">p</figure-callout>}}_1+\frac{m^2}{n^2}{p}_2---\left(3\right)$

By p ₁A ₁-p ₂A ₂=F _LAnd A ₂/ A ₁=n, obtain (p ₁-np ₂) A ₁=F _L,

So can obtain:

${\mathrm{<figure-callout\; id="1"\; label="p"\; filenames="HDA00003615156900021.png"\; state="\{\{state\}\}">p</figure-callout>}}_1=\frac{n^3{p}_s+m^2{F}_L/A_1}{n^3+m^2}---\left(4\right)$

${\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="HDA00003615156900021.png"\; state="\{\{state\}\}">p</figure-callout>}}_2=\frac{n^2{p}_s-n^2{F}_L/A_1}{n^3+m^2}---\left(5\right)$

B, in like manner, retracting when piston rod 211 (is spool 223 displacement x _V＞0) time, according to above-mentioned formula, can draw:

${{\mathrm{<figure-callout\; id="1"\; label="q\; V"\; filenames="HDA00003615156900021.png"\; state="\{\{state\}\}">q</figure-callout>}}_V}^{\&prime;}=C_d{w}_1{\mathrm{<figure-callout\; id="2"\; label="x\; V"\; filenames="HDA00003615156900021.png"\; state="\{\{state\}\}">x</figure-callout>}}_V\sqrt{\frac{2}{\mathrm{\&rho;}}{{\mathrm{<figure-callout\; id="1"\; label="p"\; filenames="HDA00003615156900021.png"\; state="\{\{state\}\}">p</figure-callout>}}_1}^{\&prime;}}---\left(6\right)$

${{\mathrm{<figure-callout\; id="2"\; label="q\; V"\; filenames="HDA00003615156900021.png"\; state="\{\{state\}\}">q</figure-callout>}}_V}^{\&prime;}=C_d{w}_2{\mathrm{<figure-callout\; id="2"\; label="x\; V"\; filenames="HDA00003615156900021.png"\; state="\{\{state\}\}">x</figure-callout>}}_V\sqrt{\frac{2}{\mathrm{\&rho;}}(p_s-{{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="HDA00003615156900021.png"\; state="\{\{state\}\}">p</figure-callout>}}_2}^{\&prime;})}---\left(7\right)$

${{\mathrm{<figure-callout\; id="1"\; label="p"\; filenames="HDA00003615156900021.png"\; state="\{\{state\}\}">p</figure-callout>}}_1}^{\&prime;}=\frac{{\mathrm{nm}}^2{p}_s+m^2{F}_L/A_1}{n^3+m^2}---\left(8\right)$

${{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="HDA00003615156900021.png"\; state="\{\{state\}\}">p</figure-callout>}}_2}^{\&prime;}=\frac{m^2{p}_s+n^2{F}_L/A_1}{n^3+m^2}---\left(9\right)$

Therefore, when piston rod 211 moving direction changed, the pressure in 21 liang of chambeies of hydraulic jack was changed to

$\left\{\begin{array}{c}{\mathrm{\&Delta;p}}_1=p_1-{{\mathrm{<figure-callout\; id="1"\; label="p"\; filenames="HDA00003615156900021.png"\; state="\{\{state\}\}">p</figure-callout>}}_1}^{\&prime;}=\frac{n(n^2-m^2)p_s}{n^3+{\mathrm{<figure-callout\; id="2"\; label="m"\; filenames="HDA00003615156900021.png"\; state="\{\{state\}\}">m</figure-callout>}}^2}\\ \mathrm{\&Delta;}{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="HDA00003615156900021.png"\; state="\{\{state\}\}">p</figure-callout>}}_2=p_2-{{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="HDA00003615156900021.png"\; state="\{\{state\}\}">p</figure-callout>}}_2}^{\&prime;}=\frac{(n^2-m^2)p_s}{n^3+m^2}\end{array}\right.---\left(10\right)$

As can be known, the servovalve in background technique is taked symmetric design (m=1) to convolution (10), due to 0＜n＜1, and Δ p ₁, Δ p ₂Absolute value inevitable greater than zero, thereby produce pressure reduction.And in the present embodiment, the area gradient ratio of first throttle window 221a and the second throttling window 222a is designed to, equate with the effective active area of rodless cavity, rod chamber, i.e. m=n, according to formula 10) can obtain,

$\left\{\begin{array}{c}{\mathrm{\&Delta;p}}_1=0\\ {\mathrm{\&Delta;p}}_2=0\end{array}\right.$

Therefore, asymmetric servovalve 22 in the present embodiment, when hydraulic jack 21 piston rods 211 stretch out or retract, the pressure reduction of its rod chamber and rodless cavity is zero, namely eliminate the phenomenon of two cavity pressure sudden changes when in the background technique, piston rod 211 moving direction change, made the work of hydraulic jack 21 comparatively stable.

For the area gradient ratio m that makes two throttling windows equates than n with two chamber effective active areas, can design in the following manner servovalve 22: as shown in Figure 2, the valve pocket of servovalve 22 is the ladder setting, the first actuator port 221 is located at the large footpath section of valve pocket, and the second actuator port 222 is located at the path section of valve pocket.Certainly, the sectional area ratio of large footpath section and path section can be according to two chamber effective active areas of the hydraulic jack 21 of its control than determining.So design, as long as process the cascade valve pocket on valve body, processing is simple.

Certainly, by designing difform two throttle window mouth-shapeds so that area gradient both inconsistent be also feasible, just, the valve body difficulty of processing of this moment will be greater than the embodiment of above-mentioned stepped valve pocket.

Except above-mentioned servo hydraulic system, the present invention also provides a kind of high-altitude operation engineering machinery, the hydraulic system that comprises working platform and leveling working platform, described hydraulic system is the described servo hydraulic system of above-mentioned arbitrary embodiment, because above-mentioned servo hydraulic system has above-mentioned technique effect, high-altitude operation engineering machinery with this hydraulic system also has identical technique effect, repeats no more herein.When above-mentioned servo hydraulic system is adopted in the leveling of high-altitude operation engineering machinery, can guarantee stability, accuracy and the rapidity of working platform leveling, improve the leveling precision.

Further, as shown in Figure 4, Fig. 4 is the structured flowchart of a kind of specific embodiment of high-altitude operation engineering machinery leveling system provided by the present invention.

High-altitude operation engineering machinery can also comprise controller, and the dip sensor of testing platform inclination angle, and dip sensor is connected with controller signals, thereby the angle signal that working platform is tilted exports controller to.Generally, the leveling of working platform is to make it be in level, therefore dip sensor detection platform angle of inclination with respect to the horizontal plane gets final product.

After controller obtains inclination angle signal, can control servovalve 22 according to the angle signal that dip sensor detects and carry out the switching of working position.Such as, after controller analytic angle signal, drawing working platform is inclined upwardly, suppose that hydraulic jack 11 is set to shore the state of working platform, can control servovalve 22 switch operating positions, so that the piston rod 211 of hydraulic jack 21 retracts, the distance of retraction can draw according to calculation of parameter such as the working platform angle of inclination that prestores and piston rod 211 length, working platform length, piston rod 211 drives working platform while retracting and is rotated down required angle, and state is up to the standard; When downward-sloping, the leveling process is just the opposite.When hydraulic jack 11 was set to lift the state of worktable, the leveling process was just the opposite.

So design, can be according to the actual angle of inclination of working platform, and automatic leveling accurately, in case operator's operate miss.

High-altitude operation engineering machinery in above-described embodiment is specially Elevating platform fire truck, can be also aerial ladder truck or aerial work platform, and such engineering machinery all has working platform, in order to carry the high-lift operation personnel, and provides the high-lift operation space.

Above a kind of high-altitude operation engineering machinery provided by the present invention and servo hydraulic system thereof all are described in detail.Applied specific case herein principle of the present invention and mode of execution are set forth, above embodiment's explanation just is used for helping to understand method of the present invention and core concept thereof.Should be pointed out that for those skilled in the art, under the premise without departing from the principles of the invention, can also carry out some improvement and modification to the present invention, these improvement and modification also fall in the protection domain of the claims in the present invention.

Claims (6)

1. servo hydraulic system, comprise hydraulic jack (21) and control the flexible servovalve (22) of described hydraulic jack (21), described servovalve (22) is provided with first throttle window (221a), the second throttling window (222a) that corresponds respectively to described hydraulic jack (21) rodless cavity, rod chamber, it is characterized in that, the area gradient ratio of described first throttle window (221a) and described the second throttling window (222a), with the effective active area of described rodless cavity, described rod chamber than equating.

2. servo hydraulic system as claimed in claim 1, it is characterized in that, the valve pocket of described servovalve (22) is the ladder setting, and described first throttle window (221a) is located at the large footpath section of described valve pocket, and described the second throttling window (222a) is located at the path section of described valve pocket.

3. servo hydraulic system as claimed in claim 1, is characterized in that, described servovalve (22) is three-position four-way valve.

4. high-altitude operation engineering machinery comprises and it is characterized in that the hydraulic system of working platform and the described working platform of leveling that described hydraulic system is the described servo hydraulic system of claim 1-3 any one.

5. high-altitude operation engineering machinery as claimed in claim 4, is characterized in that, also comprises controller, and the dip sensor that detects described working platform angle of inclination; The angle signal that described controller detects according to described dip sensor is controlled described servovalve (22) and is carried out the switching of working position.

6. high-altitude operation engineering machinery as claimed in claim 4, is characterized in that, is specially Elevating platform fire truck.

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