附录1自卸车举升系统设计浅谈摘要:本文通过对自卸车的简要设计分析, 针对长度较大的重型自卸车的特点, 从举升系统的结构设计及液压设计方面提出了相应的措施, 对重型自卸车的举升系统设计有一定的指导作用。
关键词:重载；举升；系统1、自卸车主要结构自卸车的结构主要包括举升系统、底盘、副车架、车厢等组成,2、举升机构设计分析重型自卸车举升系统在设计过程中需要解决的主要问题包括:举升形式的选取、车箱在举升过程中的稳定性、前后桥的轴荷分配合理性及液压系统的可靠性。
下面将通过底盘上设计7.2米自卸车这一具体事例,阐述自卸车举升机构系统设计的一般思路。
2.1初步确定车厢容积根据二类底盘的参数:轴距3900mm+1350mm,后悬900mm,载质量17500kg,及整后悬为1600mm的要求,车箱尺寸确定5600mm*2300mm*1500mm。
初步确定车箱在底盘上的位置为车箱后端出去底盘车架后端870mm。
在确定举升形式后,需要再通过分析计算前后桥的轴荷分配情况,验证车箱在二类车上的位置是否合理。
2.2举升形式的确定自卸车常用的举升形式主要是有F式、T式、前置直顶式等形式。
要在F 式、T式、前置直顶式三种举升形式中确定一种最合适的,就需要分别就三种情况进行分析校核。
三种举升形式各有其优缺点,前置直顶式结构紧凑、举升效率高。
工艺简单、成本较低。
但举升后稳定性差,对路面情况要求较高;F式和T式举升机构横向钢度好、举升转动圆滑平顺,油缸活塞的工作行程短,但举升力系数较大。
为了确定究竟选用哪一种举升形式最合适,笔者分别就三种情况做了理论分析。
如果选用F式和T式举升形式,最重要的对其举升力系数进行计算比较。
经计算F式举升形式的举升力系数最小是1.751,T式举升形式举升力系数最小是1.799,都不是很理想(通常举升力系数为1.6~1.7时效果较好)。
而前置直顶式油缸举升力T大于8吨就可以了。
考虑到采用F式或T式举升机构,举升非常费力,需要大的举升油缸,而且对三角臂等要求很高,不易实现。
结合前述的分析,决定采用前置直顶式举升形式。
2.3提高举升稳定性措施因本次设计的车箱长度较大,同时又采用前置直顶式举升形式,所以车箱的稳定性非常重要,需要采取措施来提高车厢举升过程中整车的稳定性,防止整车发生侧翻。
通常情况自卸车车箱连接设计采用铰轴与副车架连接,副车架通过U 型螺栓和连接板与主车架连接的结构。
本次设计我们采用了新的结构,扁钢通过焊在侧面的连接板用螺栓固定在主车架上,这样就大大降低了整车的重心,增加了稳定性。
由于车箱是通过铰轴和铰轴座来实现举升转动的,铰轴座有一定高度现在用扁钢替代了副车架,铰轴座需要安装在主车架纵梁上翼面以下,因此在主车架后端需要安装一个Z型的横梁来支撑后铰轴座,Z型的横梁总成通过螺栓固定在车架后端,同时两铰轴座之间的距离尽量加大,以增加车箱举升时的稳定性。
因车箱长度较大,设计时需考虑采用了稳定装置来增加整车稳定性,稳定装置安装在车厢中部偏前的位置。
车箱安全撑杆设计在车架左右纵梁之间,形式简单,安全可靠,操作方便。
考虑到车箱举升后,铰轴座处受力非常大,因此在铰轴座处需采用加强措施,以增加对铰轴座的支撑力。
3、举升机构液压系统设计前置直顶式的液压倾卸机构包括齿轮油泵、液压油缸、举升操纵阀、举升阀、液压油箱、管路、举升机构。
液压系统我们采用了先进的三回路系统。
液压控制系统工作原理图,。
在三回路的自卸车系统中,油液会通过流向油缸的唯一油路返回泵阀总成,在油液返回油箱的过程中,泵中的阀将会引导油液通过另一条油路,它只被用作返回油路,因为在大多数出色的油路设计中,回程油路中会安装使用容量为100gpm的过滤器,来过滤要进入油泵的污物,延长泵中零件的使用寿命。
三回路系统的主要优点在于:保证洁净的油液会始终供给油泵,而不至于当自卸车在中位或保持位置时的供油只依靠泵在转动时的内部容积。
3.1主要部件的选择液压系统主要采用海沃系统,液压油缸选用海沃多级套筒缸。
3.2液压油缸安装位置的确定安装直顶式液压油缸要求车箱和驾驶室之间有足够的空间,经研究二类底盘的布置,驾驶室后面的消音器需要移动位置。
因取消了副车架,液压油缸需要安装在主车架两纵梁之间,利用主车架上的孔,设计了一个液压油缸安装座总成。
安装座用螺栓固定在主车架左右纵梁上,液压油缸支撑轴再安装在安装座上,液压油缸支架固定在车箱前板上。
4、结束语以上是自卸车举升系统的设计过程,本次设计的的主要特点就是在整车长度较大的自卸车中采用前置直顶式举升机构,液压系统为三回路系统,采用泵阀一体式结构,工作原理简单,结构新颖;同时通过采用新结构解决了在举升过程中车厢的稳定性问题。
通过以上一个具体车型举升系统设计过程的介绍,也可以反映自卸车举升系统的一般设计思路。
附录2A Brief Description of Lift Truck System DesignAbstract：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；system1. The main structure of dump truckDump truck, including the structure of the main lift system, chassis, frame, vice,component compartments,2. lifting body design and analysisHeavy-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 initialChassis 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 liftingLift 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 aspossible 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 DesignPre-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 chooseHydraulic system is mainly used hiwassee systems, hydraulic cylinder hiwassee selected multi-level cylinder sleeve.3.2 hydraulic cylinder installation to determine the locationThe 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 theinstallationof seat, hydraulic cylinder brackets before the board in the car.4. Concluding remarksThese 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.。