CS210832B1 - Headlamp for motor vehicles - Google Patents

Abstract

The invention relates to a headlamp for motor vehicles, which consists of a paraboloid reflector cut by two horizontal planes, a diffuser and a source of passing light, in which a cylindrical filament is placed axially in the reflector in front of its focus. The headlamp provides for an increase in the level of luminosity to the area of BAND II, IV according to the ECE regulation 1, 8, 20.

Description

The invention relates to a headlamp for motor vehicles, which consists of a paraboloid reflector cut by two horizontal planes, a diffuser and a source of passing light, which is a spiral of a cylindrical bulb placed axially in the reflector in front of its focus.

The headlight has been designed to increase the level of luminosity to ZONE II, IV according to ECE regulations 1, 8, 20.

The visibility distance of a European-type dipped beam is determined by the concentration of the luminous flux at the light-dark boundary for the same headlight setting. The visibility distance therefore increases with increasing horizontal dimensions of the reflector, with decreasing focal length and, up to a certain value, with increasing diameter of the dipped beam spiral. On the contrary, the visibility distance decreases with increasing defocus, i.e. with increasing distance of the closer end of the spiral from the reflector focus.

With larger values of the horizontal dimension of the reflector, in order to reduce the vertical dimension of the reflector and thus the vertical dimension of the front grille of the motor vehicle and reduce the unfavorable ratio of the maximum luminous intensity of the main beam and dipped beam, the rotationally symmetrical surface of the reflector is limited by two horizontal planes symmetrically or asymmetrically with respect to its axis.

Greater defocusing of the low beam spiral is necessary with an increased horizontal dimension of the reflector and its increase also raises the requirement to achieve maximum axial luminosity of the high beam in headlamps with double-filament H4 bulbs, to ensure which it is desirable that the focus of the reflector lies near the center of the high beam filament, where the filament has the greatest brightness. When the reflector is cut by the upper horizontal plane, the low beam spiral in the zone symmetrical around the vertical axis of the reflector appears transversely outside ZONE II, IV,

2.0832 so the light beam from this zone illuminates the road only at a distance shorter than 25 a.

This results in a change in the geometric visibility distance of the light beam from the reflector in the area around the axis of the headlamp and the median of the lane, and a change in the photometric visibility distance of the entire headlamp.

This deficiency is eliminated in the headlamp according to the invention, in which the diffuser zone, defined depending on the height of the cutting plane and the focal length of the reflector, the diameter of the spiral of the dipped beam and the defocus of the spiral closer to the focal point F of the reflector, is designed vertically wedge-shaped towards the upper edge of the headlamp, while the angle of the wedge is such that the elementary image of the spiral maximally covers the unlit space, but so that its edge does not exceed the boundary of light and darkness and does not reduce the sharpness of this boundary and does not increase the level of dazzling luminosity of the headlamp to ZONE 111. This increases several times the geometric visibility distance of the light beam from the said zone and the visibility distance of an obstacle on the road at a distance of more than 25 m, respectively 50 m illuminated by the beam of the dipped beam of the headlamp according to the invention.

The attached drawings show an example of a headlamp according to the invention, where Fig. 1 shows a front view of the headlamp, its horizontal section A-A, vertical section B-B and section C-C through the wedge-shaped diffuser zone. Fig. 2 shows a perspective projection of the road on a projection screen in a standard arrangement according to ECE regulations 1, 8, 20, in which the image of the passing beam from the reflector is marked using curves of the same relative luminosity. Fig. 3 and Fig. 4 show examples of creating a wedge-shaped profile on the diffuser according to the invention.

Fig. 1 shows a headlamp consisting of a reflector J., a diffuser 2» a bulb 2 with a filament £ of the passing light screened to obtain the interface between light and darkness by a screen 2. The filament 4. is in the shape of a cylindrical spiral with a diameter D and is placed axially at a distance of its near end from the focus F of the reflector χ. The reflector J of focal length £ is limited by two horizontal planes, the upper of which is at a distance gy and the lower is at a distance JJjj from the axis 2 of the headlamp.

The linear angle of incidence of the reflector 1 is in the range řj^max;

Y _o = 2 arctg Sfl- j ^B o “ apex radius / Rmax \

Xnax “ ^{2 arct} « t--) ®max ^maximal radius ' (1)

By cutting the reflector with a horizontal plane at the height gy, the maximum value of the angle of incidence for the polar angle ( » Ψ _Η changes depending on it to the value

where

(2)

If we project the beam of the passing light from the reflector J. onto the projection plane according to the ECE regulation 1, 8, 20 as shown in Fig. 2, a light image is created with an unilluminated space around the axis and the headlamp, which is essentially symmetrical according to the axis of the lane and extended from the light and dark boundary to ZONE I. The geometric range of the reflector in the direction of the axis of the lane is reduced from the value of 75 m to 8 to 20 m. Furthermore, the maximum of the relative luminosity I/I is shifted outside the axis of the light beam. The shape of the unilluminated space can be defined by the polar angle HJ and by the angle «- _R , which encloses the closest point of the elementary representation of the spiral 2 by the reflector and the axis and of the headlamp. Due to rotational symmetry, this angle can only be determined as a function of the polar radius R as follows:

l _f .R I6f ² - 2D.f.(4f ² - R ² ).sign (4f ² - R ² ) ^R (4f ² + R ² ) ² + l _f .4f.(4f ² - R ² ) (3)

In a rotationally symmetrical reflector, the shape of the unlit space is rotational, and the value of its radius is obtained from relation (3) by substituting R = R _max · After cutting the reflector by a horizontal plane at height Hy, the shape of the unlit space is not rotational, but is extended into zone I along the axis of the lane. Its dimensions ψ are obtained depending on R, Ψ from relation (3) by substituting:

max ^ρΓ ° ψ - ¹⁷ H for ψ * ψ _Η (4)

To obtain sufficient photometric visibility distance, it is necessary to concentrate the maximum luminous flux into zones II, IV, i.e. to illuminate the road at a distance greater than 25 m.

For this reason, as shown in Fig. 1, a dark zone is defined in the front view of the reflector 2, which displays the light source 2 only up to BAND I. The zone is limited by the vertex radius R, the upper edge of the reflector 2 and the curve = tf (R), which is symmetrical about the vertical axis of the reflector 2 and given by:

f ψ- lf <S) l _f .R.16f ² (4f ² + R ² ) ² + l _f .4f.(4f ² - R ² )

R

000

0.02 2Df ysin ² i/.(4f ² + R ² ) ² + cos ² f. (4f ² - R ² ) ²

--.------- _a Q (4f ² + R ² ) ² + l _f .4f.(4í' ² - R ² ) (5)

At small values of the angle ot _RA , the dark zone of the diffuser 2 and the reflector 2 can be identified. To increase the luminosity to ZONE II, IV, the diffuser 2 is made vertically wedge-shaped in this dark zone towards the upper edge of the headlamp.

To achieve maximum filling of the dark area around the x-axis of the headlight, it is necessary that the vertical wedge angle _v is:

£ _v (R, ψ ) = '--<Á _R .cos ψ) η- 1 where n -· refractive index of the diffuser material.

(6)

In the case where the outer surface of the diffuser 2 3® is spherical, the wedge shape can be created according to Fig. 3 so that the diffuserS 2 d® in the shape of a negative meniscus, i.e. the inner radius Ø ₍ of the sphere is smaller than the radius R ₂ of the outer sphere. T _Q denotes the axial thickness of the meniscus.

For a given radius of the outer surface Ø _2, the scattering 2 ®® determines the radius Øj from the relationship:

R-C1 - n)[n(Ø ₂ - 5,) + (n - 1).T _Q ]

n.Řj .1? ₂ et λ

R* (7) where R - maximum radius of the zone

If the outer surface of the diffuser 2 is in the shape of a sphere, cylinder, torus, or if it is flat, the wedge shape in the vertical section can be created according to Fig. 4 so that the center of the inner radius 5 is shifted by the value Ar below the axis of the diffuser 2. For a given radius of the outer surface Ø ₂ , the values of Ar and if we do not write relation (6) in the form:

arcsine

R + AR

-F \ o

R + AR

F-qos ψ) (8)

Since the roughness of the surfaces of the reflector 1 and the diffuser 2 increase the size of the elementary image of the spiral 1, while its size is also increased by the image of the spiral £ by the shiny surface of the diaphragm í of the bulb 2, the wedge-shaped zone of the diffuser 2 is provided with strip-shaped statues, in which the ratio d/r of the width 2 to the radius £ for the purpose of reducing the dazzling luminosity to BAND III by lateral scattering is given by:

0.3 * 0.6 (tan

Ifmax + tg = 0° or using relations (1) and (2):

0.15 + 0.3 ( ^R max ^{+ H} u) (9) (10)

CORRECTION of the description of the invention to the author's certificate No. 210 8)2 Int. Cl? B 60 1/16

D 60 Q 1/24

In the description of the invention for the author's certificate No. 210 8)2, several reference numbers were printed incorrectly.

legally: p. 2,regarding = 2.arctg ( ^R o 2 f r max ⁼ O.arctg ( R _max 2f 2 3rd class order )2 ί'-ί'η atr. ),vž£dh 5 . ψ .,.ψ <R> physm^ ..... Ί 3tr.4,relation 7 íč( j ... . + (n-l ] .T„ subject, point 2 ·“*—»— n. R-^Rg

(LINE OF INVENTIONS AND DISCOVERIES

Claims (3)

SUBJECT OF THE INVENTION 1. «Ν ^(Κ 'Ψ ⁾ (Kg.cos ψ) where: n - refractive index of diffuser material (2) - angle of the nearest point of the spiral image (4) from the axis (x) of the reflector (1): R * = _f l .R.16f ^'s 1. A headlamp for motor vehicles comprising a diffuser, a paraboloid reflector limited by two horizontal planes and a cylindrical spiral-shaped dipped-beam source mounted axially in front of the reflector, characterized by dispersing (2) in its upper half within a zone symmetrical to the vertical; bounded when viewed in the direction (x) of the reflector (1) with curves if = 4 '(R): (4f ² + R ² ) ² + ipéf.Uf ² - R ² ) 25,000. cos ψ - 0.02 2D.f. 3ΐη ² (4f ² + R ^{2) 2} + cos ² y. (4 ² - R ^{1 *} Headlamp according to claim 1, characterized in that the diffuser (2) with the outer surface in the form of a sphere of radius (5 ₂ ) has a wedge-shaped zone in the form of a negative meniscus, the internal radius of which is given by RI (n) n. _(R2 - R i) + (n-1, where T R - maximum polar radius of dark zone T _Q - axial thickness of diffuser (2) n - refractive index of diffuser material (2) Headlamp according to claim 1, characterized in that the diffuser (2) with an outer surface in the form of a sphere, cylinder, torus or plane of radius (Řý) has a wedge in vertical section designed so that the center of the inner radius (R 1) is displaced vertically below the diffuser axis (2) 210832 6 by the value (AR), the value of the internal radius being determined from the relation 2.Df (4 ² - R ²⁾ .sign (4 ² - R ²⁾ (4f ² + R ²⁾ + I ² _f .4f. (4f ² R ² ) 2) ₂ (4f ² + R ^{2) 2} + L _f .4f. (4 ² - R ²⁾ where: R - polar radius with origin at the intersection of axis (x) with diffuser surfaces / - polar angle relative to vertical axis Xj. - axial distance of the proximal face of the spiral (4) from the focus (F) of the reflector (1) D - diameter of the spare cylinder of the spiral (4) f - the focal length of the reflector (1) is wedge-shaped with the base on the side of the upper edge of the headlamp, the angle _γ (R, ψ) of the vertical wedge being maximum. Headlamp according to Claims 1, 2 and 3, characterized in that the wedge-shaped zone of the diffuser (2) is provided with diffuser elements in the form of band lenses having a ratio of Width (d) to radius (r) of? 0.15 to -r · 0.3. (s + H ,.) 'max TJ where f - focal length of reflector (1) Ηθ - distance of the upper cutting plane from the focus (F) of the reflector (1) R - maximum reflector radius (1) max