Pressure angle

About: Pressure angle is a research topic. Over the lifetime, 1373 publications have been published within this topic receiving 10245 citations. The topic is also known as: angle of obliquity.

High-pressure circulating ball power steering gear

Abstract: The utility model relates to a high-pressure circulating ball power steering gear, belonging to the technical field of automotive power steering gear. The power steering gear comprises a steering rocker shaft, a side cover component, a steering nut, a valve component and a casing component, wherein the steering rocker shaft is installed on the output end of an oil cylinder casing, the steering nut is installed on a steering screw, the end portion of the steering screw is connected with an input shaft, and a safety valve is installed on the valve component. The pressure angle of a gear section on the steering rocker shaft is 27 degrees five minutes, the gear sector can bear torsion load below pressure of 20 MPa, thereby improving the integral strength of the steering rocker shaft. One end of a bearing is fixed with the oil cylinder on one end, and the other end of the bearing is positioned by an elastic gasket for hole which can be conveniently assembled, thereby guaranteeing the positioning stability of the bearing in the cylinder, and preventing the bearing from axially displacing in the cylinder. The high-pressure circulating ball power steering gear solves the problems of faults of the steering gear, such as clamping, heaviness and the like as the steering gear is located in limit position, and the steering screw has insufficient rigidity. And the service life of the steering gear is effectively protected.

Perturbed cross-flow boundary layer: nontrivial effects of the obliquity angle at small and high reynolds numbers

Abstract: We carry out an exploratory linear study on the transient dynamics of arbitrary three-dimensional perturbations acting on the Falkner-Skan-Cooke cross-flow boundary layer. The analysis is in particular focused on the effects of the direction of the perturbations at low and high Reynolds numbers. We show evidence of a non-trivial dependency of the transient and asymptotic behavior on the travelling waves obliquity with respect to the base flow. The Falkner-Skan-Cooke cross flow boundary layer stability has been analyzed in literature using modal theory [1], in the context of receptivity and transient optimal perturbations [2, 3] and experimentally [4]. Here we treat the full linear three-dimensional perturbation problem by paying particular attention to the role of the obliquity of the perturbation with respect to base flow direction. In literature there are few contributions with a specific focus on the effect of the angle of obliquity on the perturbation transient life. Works on optimal perturbations [3] usually consider obliquity angles in the neighborhood of a fixed value. For instance, Breuer and Kuraishi [2] investigated the direction of the waves, but varying simultaneously φ and k. The exploratory analysis here proposed highlights a rich and, for certain aspects, counterintuitive scenario on the role of the perturbation direction. We observed that the "instability" of the waves does not depend in a trivial way from their obliquity: there are in fact configurations where both the longitudinal and orthogonal waves are unstable while oblique ones in-between are stable. Figure 1. (a) Reference system and sketch of the cross-flow boundary layer: θ is the angle of cross-flow, φ is the angle of obliquity. (b) Components of the base flow, U(y), W (y), β = −0.1988, 1 and θ = π/6, π/4, π/3. We consider suband supercritical flow configurations (the Reynolds number, based on the displacement thickness δ∗, is equal to 100 and 5000), subject to adverse and favorable pressure gradients (Hartree parameter, β, equal to -0.1988 and 1, respectively). The cross flow angle, θ, between the streamwise direction and the chordwise direction, is taken equal to π/6, π/4, π/3 (see Figure 1). Concerning the direction and wavelength of the perturbation, we vary both the obliquity angle with respect to the streamwise direction and the polar wavenumber, φ and k. The transient and asymptotic behavior of the perturbative waves is observed through the amplification factor, G(t) (defined as the kinetic energy density, E(t), normalized over its initial value), the temporal growth rate, r = log(E(t))/2t, and the frequency, ω. This last is defined as the temporal derivative of the phase at a fixed distance from the wall. Fig. 2 shows the effect of the obliquity angle over two very different values of the Reynolds number. The amplification factor, G(t), is shown in the top panels, the frequency, ω(t), in the bottom panels. Panel (a) contains the first result that we wish to highlight here. One can see that even at a Re value as low as 100, in the presence of a sufficiently high pressure gradient, a small range of unstable longitudinal wavenumbers still exist: the longitudinal wave is unstable, while the oblique and the orthogonal waves have an initial decay followed by a transient growth and a final decay. Panels (b) and (c) present the case with the higher Reynolds number, 5000. Here, both a favorable and an adverse pressure gradient are considered together with a cross flow angle of π/6. In the favorable situation, the orthogonal wave is unstable while the longitudinal and oblique perturbations are asymptotically stable, but have a growth-decay phase in the early transient. In panel (c), the most unstable configuration achievable with our choice of parameters, we see that the longitudinal and the orthogonal waves are unstable but oblique waves in between are not, and this is unexpected. Because, usually, if one sees Figure 2. Role of the obliquity angle, φ = 0.π/4, π/2. Temporal evolution of the amplification factor, G(t) (panels a, b, c), and the frequency, ω(t) (panels d, e, f). (a-d) Re = 100, β = −0.1988, θ = π/4, k = 0.2. (b-e) Re = 5000, β = 1, θ = π/6, k = 0.4. (c-f) Re = 5000, β = −0.1988, θ = π/6, k = 0.4. Figure 3. Role of θ: Temporal evolution of the amplification factor,G(t) (panel a), and the temporal growth rate r(k) in the asymptotic limit (panel b), β = −0.1988, Re = 5000, φ = 0. Pinch points results by Taylor and Peake [1] are added for a qualitative comparison. instability in the longitudinal direction, one then sees a progressive tendency to stability toward the orthogonal direction, and viceversa. Instead, here intermediate angles, as φ = π/4, have an intense initial growth and then become stable. Independently of the stable or unstable asymptotic behavior of the perturbation, the frequency along the transient present sudden impulsive variations, which we may describe as frequency jumps (see panels d-e-f). We interpret these jumps as the transition between the early part of the transient and the beginning of an intermediate term that show up for times large enough for the influence of the fine details of the initial condition to disappear. The combined effect of β and θ has been investigated by Taylor and Peake [1]. They found that asymptotically the pinch points with an adverse pressure gradient flow are more unstable at lower cross flow angles, while for negative pressure gradient the opposite is true. In Fig. 3, we show that this result is valid not only for the pinch point formulation but, more in general, for an arbitrary variation of the perturbation wavelength. A comparison with available data from [1] is presented in panel (b). Even if the Reynolds number is different (1000 versus 5000) the comparison is good. We have obtained these results by adopting the initial-value problem formulation in the velocity-vorticity formulation. We perform a Laplace-Fourier transformation of the governing disturbance equations in the streamwise and spanwise directions, and then numerically solve the resulting partial differential equations [5, 6]. This approach offers an alternative means for which arbitrary initial conditions are imposed and their full temporal behavior, including both the early transient and the long-time asymptotics, can be observed. As initial condition we consider a Gaussian function, v(t = 0, y) = y exp(−y.), ωy(t = 0, y) = 0. Such initial condition concentrates the energy of the wave in the shear region [7]. References [1] Tayor, M. J., Peake, N. 1997, J. Fluid Mech. 355, 359–381. [2] Breuer, K. S., Kuraishi, T. 1994, Phys. Fluids 6, 1983-1994. [3] Corbett, P., Bottaro, A. 2000, J. Fluid Mech. 435, 1-23. [4] Saric, W. S., Reed, H. L., White, E. B. 2003, Annu. Rev. Fluid Mech 35, 413–440. [5] Scarsoglio, S., Tordella, D., Criminale, W. O. 2009, Stud. Applied Math. 123, 153–173. [6] Scarsoglio, S., Tordella, D., Criminale, W. O. 2010, Phys. Rev. E 81, 036326/1-9. [7] Lasseigne, D. G., Joslin, R. D., Jackson, T. L. & Criminale, W. O. 1999, J. Fluid Mech. 381, 89–119.

Grooved Cam Mechanism With a Translating Follower Having an Added Ternary-Roller Intermediate Link

Abstract: Abstract The paper presents an analytical approach for designing grooved cam mechanisms with a modified arrangement of the common translating follower. That is, an intermediate link having three rollers is added between the cam and the common follower. On the basis of an existing cam mechanism with a common roller follower, an intermediate link that has three rollers is added between the cam and the common follower. Such a cam mechanism has two sets of profile and can create multiple contact points between the cam and the follower at any instant. The two sets of profiles of such a cam mechanism can serve as the grooved types. Since the follower has three rollers that can simultaneously contact the cam at any instant, it can be positively driven along the guided groove of the cam contour. The contact forces and contact stresses of such a cam mechanism are analyzed to illustrate the advantage of spreading the force transmission and reducing the contact stress of this uncommon follower. The obtained results indicate that the contact stress at the surface of the cam and the follower for such a cam mechanism can be reduced by 30 to 47% in comparison with those of the cam mechanism with a common translating roller follower. In conclusion, the cam mechanism with a translating follower having an added ternary-roller intermediate link can be a preferable choice for the applications that follower is against heavy loads or moves at high speed.

Varied involute profile travelling wheel of coal mining machine

Abstract: The utility model discloses a varied involute profile travelling wheel of a coal mining machine, which mainly solves the technical problems of lowering a pressure angle and the like when the junction pitch of two sections of pin rows of a conveyor is changed and meshed. The varied involute profile travelling wheel of the coal mining machine adopts the following technical scheme that the profile curve of the wheel tooth of the travelling wheel is the varied involute obtained after a standard involute is subjected to radial and tangential deflection, and the modulus m value of the wheel tooth of the travelling wheel is more than 50. Thus, the varied involute profile travelling wheel is suitable for the travelling wheel of a large-power coal mining machine, and is especially suitable for the travelling wheel of a super-large power coal mining machine.

Parametric plunger movement law-based minimum base circle cam profile design method

Abstract: The invention discloses a parametric plunger movement law-based minimum base circle cam profile design method. The method comprises the following steps of: calculating a pressure angle, a curvature radius and a contact stress of a cam according to a plunger movement lift curve, a pump-end fuel pressure characteristic curve, a roller diameter matched with the cam and a set base circle radius initial value; carrying out iterative calculation through gradually increasing the base circle radius until the pressure angle, the curvature radius and the contact stress satisfy design criteria of pressure angles, curvature radii and stress conditions, so as to obtain a minimum base circle radius satisfying a cam profile design criterion; and obtaining a finally determined cam profile according to a lift curve of a plunger movement process, the minimum base circle radius and the roller diameter matched with the cam. The method is capable of rapidly obtaining minimum cam base circle radii suitablefor cam lift curves, so as to rapidly obtain complete oil supply cams.