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黑龍江工程學(xué)院本科生畢業(yè)設(shè)計
附錄1
自卸車舉升系統(tǒng)設(shè)計淺談
摘要:本文通過對自卸車的簡要設(shè)計分析, 針對長度較大的重型自卸車的特點(diǎn), 從舉升系統(tǒng)的結(jié)構(gòu)設(shè)計及液壓設(shè)計方面提出了相應(yīng)的措施, 對重型自卸車的舉升系統(tǒng)設(shè)計有一定的指導(dǎo)作用。
關(guān)鍵詞:重載；舉升；系統(tǒng)
1、自卸車主要結(jié)構(gòu)
自卸車的結(jié)構(gòu)主要包括舉升系統(tǒng)、底盤、副車架、車廂等組成,
2、舉升機(jī)構(gòu)設(shè)計分析
重型自卸車舉升系統(tǒng)在設(shè)計過程中需要解決的主要問題包括:舉升形式的選取、車箱在舉升過程中的穩(wěn)定性、前后橋的軸荷分配合理性及液壓系統(tǒng)的可靠性。下面將通過底盤上設(shè)計7.2米自卸車這一具體事例,闡述自卸車舉升機(jī)構(gòu)系統(tǒng)設(shè)計的一般思路。
2.1初步確定車廂容積
根據(jù)二類底盤的參數(shù):軸距3900mm+1350mm,后懸900mm,載質(zhì)量17500kg,及整后懸為1600mm的要求,車箱尺寸確定5600mm*2300mm*1500mm。初步確定車箱在底盤上的位置為車箱后端出去底盤車架后端870mm。在確定舉升形式后,需要再通過分析計算前后橋的軸荷分配情況,驗證車箱在二類車上的位置是否合理。
2.2舉升形式的確定
自卸車常用的舉升形式主要是有F式、T式、前置直頂式等形式。要在F式、T式、前置直頂式三種舉升形式中確定一種最合適的,就需要分別就三種情況進(jìn)行分析校核。三種舉升形式各有其優(yōu)缺點(diǎn),前置直頂式結(jié)構(gòu)緊湊、舉升效率高。工藝簡單、成本較低。但舉升后穩(wěn)定性差,對路面情況要求較高;F式和T式舉升機(jī)構(gòu)橫向鋼度好、舉升轉(zhuǎn)動圓滑平順,油缸活塞的工作行程短,但舉升力系數(shù)較大。
為了確定究竟選用哪一種舉升形式最合適,筆者分別就三種情況做了理論分析。如果選用F式和T式舉升形式,最重要的對其舉升力系數(shù)進(jìn)行計算比較。經(jīng)計算F式舉升形式的舉升力系數(shù)最小是1.751,T式舉升形式舉升力系數(shù)最小是1.799,都不是很理想(通常舉升力系數(shù)為1.6~1.7時效果較好)。而前置直頂式油缸舉升力T大于8噸就可以了?？紤]到采用F式或T式舉升機(jī)構(gòu),舉升非常費(fèi)力,需要大的舉升油缸,而且對三角臂等要求很高,不易實現(xiàn)。結(jié)合前述的分析,決定采用前置直頂式舉升形式。
2.3提高舉升穩(wěn)定性措施
因本次設(shè)計的車箱長度較大,同時又采用前置直頂式舉升形式,所以車箱的穩(wěn)定性非常重要,需要采取措施來提高車廂舉升過程中整車的穩(wěn)定性,防止整車發(fā)生側(cè)翻。通常情況自卸車車箱連接設(shè)計采用鉸軸與副車架連接,副車架通過U型螺栓和連接板與主車架連接的結(jié)構(gòu)。本次設(shè)計我們采用了新的結(jié)構(gòu),扁鋼通過焊在側(cè)面的連接板用螺栓固定在主車架上,這樣就大大降低了整車的重心,增加了穩(wěn)定性。由于車箱是通過鉸軸和鉸軸座來實現(xiàn)舉升轉(zhuǎn)動的,鉸軸座有一定高度現(xiàn)在用扁鋼替代了副車架,鉸軸座需要安裝在主車架縱梁上翼面以下,因此在主車架后端需要安裝一個Z型的橫梁來支撐后鉸軸座,Z型的橫梁總成通過螺栓固定在車架后端,同時兩鉸軸座之間的距離盡量加大,以增加車箱舉升時的穩(wěn)定性。因車箱長度較大,設(shè)計時需考慮采用了穩(wěn)定裝置來增加整車穩(wěn)定性,穩(wěn)定裝置安裝在車廂中部偏前的位置。車箱安全撐桿設(shè)計在車架左右縱梁之間,形式簡單,安全可靠,操作方便?？紤]到車箱舉升后,鉸軸座處受力非常大,因此在鉸軸座處需采用加強(qiáng)措施,以增加對鉸軸座的支撐力。
3、舉升機(jī)構(gòu)液壓系統(tǒng)設(shè)計
前置直頂式的液壓傾卸機(jī)構(gòu)包括齒輪油泵、液壓油缸、舉升操縱閥、舉升閥、液壓油箱、管路、舉升機(jī)構(gòu)。液壓系統(tǒng)我們采用了先進(jìn)的三回路系統(tǒng)。液壓控制系統(tǒng)工作原理圖,。在三回路的自卸車系統(tǒng)中,油液會通過流向油缸的唯一油路返回泵閥總成,在油液返回油箱的過程中,泵中的閥將會引導(dǎo)油液通過另一條油路,它只被用作返回油路,因為在大多數(shù)出色的油路設(shè)計中,回程油路中會安裝使用容量為100gpm的過濾器,來過濾要進(jìn)入油泵的污物,延長泵中零件的使用壽命。三回路系統(tǒng)的主要優(yōu)點(diǎn)在于:保證潔凈的油液會始終供給油泵,而不至于當(dāng)自卸車在中位或保持位置時的供油只依靠泵在轉(zhuǎn)動時的內(nèi)部容積。
3.1主要部件的選擇
液壓系統(tǒng)主要采用海沃系統(tǒng),液壓油缸選用海沃多級套筒缸。
3.2液壓油缸安裝位置的確定
安裝直頂式液壓油缸要求車箱和駕駛室之間有足夠的空間,經(jīng)研究二類底盤的布置,駕駛室后面的消音器需要移動位置。因取消了副車架,液壓油缸需要安裝在主車架兩縱梁之間,利用主車架上的孔,設(shè)計了一個液壓油缸安裝座總成。安裝座用螺栓固定在主車架左右縱梁上,液壓油缸支撐軸再安裝在安裝座上,液壓油缸支架固定在車箱前板上。
4、 結(jié)束語
以上是自卸車舉升系統(tǒng)的設(shè)計過程,本次設(shè)計的的主要特點(diǎn)就是在整車長度較大的自卸車中采用前置直頂式舉升機(jī)構(gòu),液壓系統(tǒng)為三回路系統(tǒng),采用泵閥一體式結(jié)構(gòu),工作原理簡單,結(jié)構(gòu)新穎;同時通過采用新結(jié)構(gòu)解決了在舉升過程中車廂的穩(wěn)定性問題。通過以上一個具體車型舉升系統(tǒng)設(shè)計過程的介紹,也可以反映自卸車舉升系統(tǒng)的一般設(shè)計思路。
附錄2
A Brief Description of Lift Truck System Design
Abstract： In this paper, dump truck through a brief design analysis, in view of the length of the larger features of heavy-duty dump truck, lifting the system from node
Structure design and hydraulic design of the corresponding measures for the lifting of heavy truck design a certain guiding function.
Key words： heavy-duty；lifting；system
1. The main structure of dump truck
Dump truck, including the structure of the main lift system, chassis, frame, vice,component compartments,
2. lifting body design and analysis
Heavy-duty dump truck lifting system in the design process of the main issues that need to be addressed include: lifting forms of selection, in the lift car in the process of stability, before and after the bridge, the reasonableness of axle-load distribution and hydraulic system reliability. Chassis by following the design of 7.2 meters on concrete examples of the dump truck, dump truck lifting mechanism on the general idea of system design.
2.1 Compartment volume to determine initial
Chassis in accordance with the parameters: Wheelbase 3900mm +1350 mm, rear overhang 900mm, set the quality of 17500kg, and the whole 1600mm rear overhang for the request to determine car-size 5600mm * 2300mm * 1500mm. Determine the initial car position in the chassis for the car back out of theback-end chassis frame870mm. In determining the form of lifting, the need for further analysis of Count before and after the bridge and axle-load distribution of the car to verify the location of the vehicle in the second category is reasonable.
2.2 determine the form of lifting
Lift truck used mainly in the form of F-type, T-style, front-straight top form. In F-type, T-style, front-straight top three identified in the form of lifting one of the most suitable, we need three conditions on the analysis of calibration. Lift the form of the three has its own advantages and disadvantages of pre-straight-top compact structure, lifting and high efficiency. Simple process with low costs. However, after lifting the stability of poor road conditions on the higher; F-type and T-type lifting mechanism a good degree of cross-cutting steel, smooth lifting smooth rotation, the fuel tank of the work piston short trip, but the lift coefficient than the Great.
In order to determine whether the choice of what kind of lifting the most appropriate form, the author of three cases were done on the theoretical analysis. If the selected F-type and T-type lifting form, the most important of its calculated lift coefficient comparison. By calculating the F-type forms of lifting lifting the smallest coefficient is 1.751, T-type lifting the smallest form of lift force coefficient is 1.799, it is not ideal (usually lift coefficient of 1.6 to 1.7 when the effect of better). The front straight top edge lifting the fuel tank T is greater than 8 tons of it. Taking into account the use of F-type or T-type lifting mechanism, very easy lifting, lifting the need for large tanks, but also to the triangular arm, such as demanding and difficult to achieve. Combination of the foregoing analysis, decided to adopt the prefix form of straight Lift top.
Lifting measures to improve the stability of 2.3 Due to the design of thelength of the larger car, at the same time, the use of pre-straight lifting top form, so the stability of car is very important, need to take measures to improve the process of lifting carriage vehicle stability, prevent the occurrence of vehicle rollover. Dump Truck car normally used to connect the design of hinge axis and sub-frame connection, the Deputy frame through the U-bolts and connect the main frame structure. The design we have adopted a new structure, flat steel, through welding at the side of fixed with bolts on the main frame, thus greatly reducing the vehicle's center of gravity to increase stability. As the car through the hinge axis and the hinge axis to achieve the lifting Block rotation, hinge axis blocks now have a high degree of flat steel to replace the Vice-trailers will need to install seat hinge axis frame in the main beam on the wing surface below the main Frame back-end need to install a Z-shaped beams to support Block after the hinge axis, Z-shaped beam through the bolt assembly back-end fixed in the frame, while the two-axis hinge as much as possible the distance between blocks to increase to increase the car example or stability. Due to the length of the larger car, the design would have to consider the stability of devices used to increase vehicle stability, the stability of the central unit installed on the inside of the location of the former side. Car safety design in the frame around pole between the longeron, the form of simple, safe, reliable, easy to operate. After taking into account the lifting carriage, Block Department hinge axis force is very large, and therefore hinge axis in the Block Office, to strengthen measures to be adopted to increase the hinge axis of the support seat edge.
3. Hydraulic Lift System Design
Pre-straight top-style, including the dumping of hydraulic gearpumps,hydraulic cylinder, control valve lift, valve lift, hydraulic tanks, piping, lifting mechanism. Hydraulic system we use an advanced three-loop system. Hydraulic control system schematics,. The dump truck in the three-loop system, the oil will flow to the fuel tank through the valve assembly to return to the only circuit in the oil return to tank, the pump will help to guide the valve through a separate oil circuit only be used as a return circuit, because in most excellent circuit design, the return will be installed in circuit capacity 100gpm use filters to filter the dirt to enter the pump to extend the use of pump parts life. Three-loop system, the main advantages are: to ensure that clean oil will always supply pumps, and not when the dump truck in the position or to maintain only the reliance on the oil pump in the internal volume rotation.
3.1 The main components to choose
Hydraulic system is mainly used hiwassee systems, hydraulic cylinder hiwassee selected multi-level cylinder sleeve.
3.2 hydraulic cylinder installation to determine the location
The installation of hydraulic cylinder straight-top car and the driver's request there is enough room between that having studied the arrangement of second-class chassis, the cab behind the need to move the location of muffler. The abolition of the Vice-frame, hydraulic oil tanks need to install a beam in the main frame between the two, using the hole on the main frame, the design of the installation of a hydraulic cylinder assembly seat. Block with bolts installed in the main frame about a fixed beam, the hydraulic cylinder support shaft and then installed in theinstallation of seat, hydraulic cylinder brackets before the board in the car.
4. Concluding remarks
These are the lift truck system design process, the main features of the design is the length of the vehicle used in large dump truck front straight top lifting body, the hydraulic system for the three-loop system, the use of pump valve all-in-one structure, working principle of simple and novel structure; At the same time, through the introduction of new structures to solve the process of lifting the car stability. Through more than a specific model of the lifting system of the design process, the lift truck can also reflect the general design of the system.
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