Design of a non circular gear Mechanism with Twice Unequal Amplitude Transmission Ratio

This study proposes a new non–circular gear transmission mechanism with an involute–cycloid composite tooth profile to realize the twice unequal amplitude transmission (In a complete rotation cycle of gear transmission, instantaneous transmission ratio has twice fluctuations obvious with unequal amplitude) of non–circular gears. The twice unequal amplitude transmission ratio curve was designed based on Fourier and polynomial functions, the change law of the Fourier coefficient on the instantaneous transmission ratio(In non-circular gear transmission, the transmission ratio changes with time, and the transmission ratio of non-circular gear should be instantaneous transmission ratio) was analyzed, and the pressure angle and contact ratio of the involute–cycloid composite tooth profile was calculated. The involute–cycloid composite tooth profile non–circular gear was machined by WEDM technology, while its meshing experiment was performed using high-speed camera technology. The results demonstrate that the instantaneous transmission ratio curve value obtained via the high-speed camera experiment was consistent with the simulation value of virtual software. Furthermore, the involute–cycloid composite tooth profile was applied in the seedling pickup mechanism of non–circular gear planetary gear train. The possibility of the application of the involute–cycloid composite tooth profile in the seedling pickup mechanism was verified by comparing the consistency of the theoretical and simulated seedling picking trajectory.

Lightweight Design and Dynamics Analysis of ZYL-15000D Directional Drill Reducer

Since the output torque of the rotary reducer of the ZYL-15000D-kilometer directional drill is proportional to the gear train transmission ratio, the output torque is large enough when the input speed and output speed meet the design goal. This paper selects the method of reducing the transmission ratio to optimize the size parameters of the reducer. MATLAB genetic algorithm is used in the optimization design, and the minimum volume of the rotary part reducer is taken as the objective of optimization design, while the design variables and constraints are determined. The optimal value of design variables was obtained through optimization, and the parameter values of each gear were determined accordingly. Through analysis, the total volume of the optimized gear reducer was reduced by 49.6%. Then, the 3D model of the optimized gear was created, and the analysis of the transient dynamics of the optimized gear was carried out with ANSYS Workbench software. According to the analysis results, the optimized gear met the strength requirements and provided a reference for the subsequent optimization design of other types of gear reducers.

A straightforward and miniature implementation method of postural synergies for replicating human grasp characteristics accurately and intuitively

The postural synergies have great potentials to replicate human grasp characteristics, simplify grasp control and reduce the number of hardware needed actuators. However, due to the complex mapping relationship and jagged transmission ratio, the implemented mechanisms are always too bulky and loose which greatly limits its application. For current solutions, the replicating accuracy of motion characteristics or control intuition are compromised, and hitherto no work reports the replicating errors in literatures. To overcome these limitations, we present a novel design framework to determine the actuation configuration, implemented scheme and physical parameters. In this way, the mechanism is miniaturized and can be compactly embedded in hand palm, a self-contained synergy robot hand that integrated with mechanism, sensors and suited electrical system is built. The experiments demonstrate that the robot hand can accurately replicate the motion characteristics of two primary synergies, keep the control intuition to simplify grasp control, perform a better anthropomorphic motion capability and grasp different objects with versatile grasp functionality.

Cost optimization of two-stage helical gearboxes with second stage double gear-sets

In practice, the cost of a gearbox plays a very important role in the trade. Therefore, reducing the cost of gearboxes is an important task not only when manufacturing the gearboxes but also when designing them. In order to reduce the cost of a gearbox, there are many solutions in which determining the optimal partial gear ratios of a gearbox is an effective measure. This is because it not only the size, the mass but also the cost of a gearbox depends greatly on the partial gear ratios. This work presents a method for calculating the cost function of two-stage helical gearboxes with second-stage double gear-sets based on the mass of the components that construct the gearbox. The cost objective function is minimized to achieve the optimal transmission ratios. Furthermore, screening experiments are carried out with nine important input parameters that have significant effects on the optimum transmission ratio of the second stage. These parameters are the total gearbox ratio, the coefficient of wheel face width of the first stage, coefficient of wheel face width of the second stage, the allowable contact stress of the first stage, the allowable contact stress of the second stage, the output torque, the cost of gearbox housing, the cost of gears, and the shaft cost. The experimental results of were analysed by using the Analysis of Variance (ANOVA) method with the help of Minitab 19 software. The results demonstrate that the effective weight of the input parameters and their interactions on the output response was investigated. Also, a regression model for computing the optimal transmission ratio of the second stage was proposed. This brings significance not only in the design process but also in manufacturing since the gearbox cost can decrease

Research and Manufacturing of Oval Gear Pair Applied in Rotor of a Roots Type Compressor

This study presents a method of shaping the tooth profile of an oval gear pair with the modified cycloid profile of the ellipse. The driving oval gear was shaped by a rack cutter with the profile of an improved cycloid, and the tooth profile of the driven oval gear was shaped by a shaper cutter to ensure that gear pair will mesh accurately with a function of transmission ratio. Mathematical model of the oval gear pair was established according to the theory of the non-circular gear with consideration to the conditions of the design parameters to avoid undercutting and tooth distribution of the oval gear. An improved pair of cycloid oval gears is designed and manufactured according to the results of the theoretical calculation. Furthermore, this gear pair is specifically applied to a Roots-type compressor to demonstrate its applicability in special cases where the traditional cylindrical gear pair cannot be replaced.

Research and analysis of steering-by-wire system stability

In this paper, the basic structure of steer-by-wire system is firstly introduced, and the steering stability of steer-by-wire system is summarized by means of stability control method and variable angle transmission ratio method. Finally, the unstudied direction of steer-by-wire system at this stage is summarized, and the intelligent steer-by-wire system is prospected, which provides basic information and ideas for the study of steering stability of steer-by-wire system.

Improving the Efficiency of a Compact Inline Hydro-Mechanical Transmission (i-HMT) at Lock-Up

A hydro-mechanical transmission (HMT) transmits power both mechanically and hydraulically allowing continuously variable transmission ratios and more efficient transmission than hydrostatic transmission. A conventional HMT tends to be costly and bulky since it has a hydrostatic transmission in parallel with a mechanical transmission. An alternative is a compact inline configuration that utilizes a two-shafted pump that is mechanically and hydraulically connected to a motor. This avoids the need for a planetary gear set while providing the HMT functionality. When the pump/motor displacement is zero, all of the power is transmitted mechanically and the transmission ratio is unity, a condition referred to as lock-up that is expected to be very efficient. Previous research however has shown significant losses at this operating condition in experiments. This is thought to be caused primarily by compressibility losses due to the repeated unnecessary opening and closing of the distributor valves. This paper first models the Hondamatic in simulations to confirm that compressibility losses contribute to the low efficiency at lock-up. Second, the paper proposes a solution to reduce these compressibility losses by means of a second cam mode that closes the distributor valves to prevent flow between the piston and the high and low pressure volumes. The performance of the existing inline HMT and the proposed solution at lock-up are modeled in simulations and compared. The results indicate a 10% increase in efficiency at lock-up.

21 Unravelling Transmission Ratio Distortion Across the Genome of a Crossbreed Beef Cattle Population

Transmission ratio distortion (TRD) is a process when one allele from either parent is preferentially transmitted to the offspring. The identification of genomic regions affected by TRD might help in the detection of lethal alleles or potential genes affecting reproduction. Here, we investigated TRD in crossbreed beef cattle population aiming to identify genomic regions showing altered deviations in segregation that could be affecting reproduction performance. A total of 237 genotyped animals were used including 46 sires, 80 dams, and 111 parent-offspring (trios). The predominant breeds of these animals were Angus (61.83%), Simmental (18.99%), Gelbvieh (6.12%), Charolais (3.65%), Hereford (2.46%) and Limousin (1.57%). After excluding SNPs with minor allele frequency lower than 0.05 and call-rate lower than 0.90, a total of 369,902 autosomal SNPs were retained for further analyses. The SNP-by-SNP analysis was performed within a Bayesian framework using TRDscanv.2.0 software, using 100,000 iterations, with 10,000 iterations being discarded as burn-in. As table 1 shows, 33 SNPs were identified with TRD, considering a Bayes Factor (BF)≥100 and the approximate empirical null distribution of TRD at 0.01% margin error. Among them, 26 SNPs were parent-unspecific and 7 SNPs were parent-specific TRD. For parent-specific TRD, 214 were identified for sire- and 162 for dam-TRD (BF≥100). Among them, 4 SNPs were detected with sire- and dam-TRD in opposite direction of preference of transmission. Preliminary functional and positional analysis was performed using the list of TRD regions with BF≥100 and the approximate empirical null distribution of TRD at 0.01% margin error. For sire-TRD, 14% of the identified QTL (n = 254) were related to non-return rate. For dam-TRD, 21 regions related to conception rate were found (1.5%) and 13 regions related to stillbirth (0.93%). Haplotype analysis is in progress to identify additional candidate regions and alleles with TRD to better understand this phenomenon in a crossbreed beef population.

The Mathematical Model of Curve-Face Gear and Time-Varying Meshing Characteristics of Compound Transmission

The curve-face gear pair is a new type of gear pair with variable transmission ratio for spatial finite helical motion. In this paper, mathematical models of a new developed curve-face gear were simplified and obtained directly by the standard shaper. The subsequent studies on the curve-face gear compound transmission characteristics were further analyzed by the combinations of the principle of space gearing and screw theory. Firstly, the conjugate tooth surface geometry as well the point contact traces of curve-face gears were derived. Secondly, the geometric relationships between gear pair and the corresponding meshing characteristics were evaluated by several basic geometric elements, including instantaneous screw, axodes, striction curve, and conjugate pitch surface. Based on that analysis, it was found that the tooth contact normal was reciprocal to the instantaneous twist, which demonstrated that the conjugate motion with the desired transmission ratio could be realized in current curve-face gear compound transmission. Moreover, the time-varying slip characteristics of the curve-face gear pair were also revealed, that is, rolling and sliding action coexist at all contact on the tooth surfaces. In brief, this work provided the theoretical basis for following researches on machining curve-face gear with standard shaper.