JPS58110373A - Rack pinion type steering unit - Google Patents

Abstract

PURPOSE:To reduce the module consisting of a number of pinions and the rack gears of the rack shaft without decreasing transmission torque by engaging each of the pinions with the rack gears and simultaneously driving them by the revolution of a handle shaft. CONSTITUTION:On a rack shaft 1, the first pinion 3a that is directly driven in turn by a handle is engaged with the second pinion 3b that is driven in turn by the pinion 3a through gears. The first pinion 3a is revolved in the same direction as the handle shaft by the revolution of the handle and moves the rack shaft 1 in one direction. Besides, since the second pinion 3b is engaged with the second rack gear train 5b, it also moves the rack shaft 1 in the same direction. As a result, the torque transmitted by the revolution of the handle shaft is shared by the first and second pinions 3a and 3b and both the moldule of the gear and the rack stroke can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention meshes and engages a pinion that is rotatably operated by rotation of a handle with the rack teeth of a rank shaft forming a part of a steering link, and the rotation of the pinion causes the rack shaft to fully reciprocate. This invention relates to a rack and pinion type steering device for automobiles that deflects wheels by moving them.

This type of steering device is suitable as a steering device for front-wheel drive vehicles, and its use has increased significantly in recent years with the spread of front-wheel drive vehicles. However, with this type of steering device, as described below, it is difficult to obtain a large gear ratio, a large deceleration ratio between the steering wheel and the wheels, and there are many sliding parts due to the structure. The disadvantage is that the torque required to operate the knob is large. The gear ratio of this type of steering device is determined by the degree of wheel deflection angle for the same amount of movement of the rack shaft, that is, the specifications of the steering link system, and the degree of rank stroke for the same amount of rotation of the pinion, that is, the gears of the pinion and rack. It is determined by the specifications.

In order to obtain a large gear ratio, for example, in the former case it is necessary to increase the arm length of the knuckle arm and at the same time increase the stroke range of the rack shaft, but this is difficult to achieve due to many restrictions due to the vehicle body structure. Also, in the latter case,
Rack stroke amount (L) relative to pinion/rotation
is the pinion m number f Zp, and the tooth module m1
Therefore, in order to reduce the gear ratio, that is, the rack stroke relative to the rotation of the binion, either reduce the rack helix angle (βR) or reduce the number of teeth (ZP) Th of the binion. Or, the tooth module (m) f is required to be made smaller. Reducing the helix angle (βR) of the rank will reduce the strength of the pinion, and reducing the number of teeth (ZP) of the pinion will reduce the meshing strength and impair the smooth meshing condition. Since reducing the module (m) of the tooth reduces the strength of the tooth, there is a practical limit in either case. For this reason, the gear ratio of the conventional type steering device is /lI~/9, which is smaller than other steering electric devices, and is considered for practical use, and the rack and pinion type steering device has a small vehicle weight. Its small size and sharp steering wheel were only used in sports cars that were seen in the East. However, since this type of steering system is suitable for front-wheel drive vehicles, there has been a desire for one with a large gear ratio that can also be applied to large vehicles.

Conventionally, as seen in British Patent No. G/2.9.23, for example, it has been known to sharpen the gear ratio by slowing down the rotation of the handle shaft and then transmitting it to the pinion. However, in this case, the operating torque of /$ is amplified and transmitted to the pinion, so the module of the tooth of the rack and pin is increased so that the amplified torque VC:4i-1 is increased. It is necessary to do so. Incidentally, considering the maximum torque that acts in normal conditions such as when the wheels are locked, the rack and binion teeth must be designed to withstand the transmission torque of 20Kg・f:'m~30Ky・mouth. For example, the rotation of the spindle must be reduced by 7 times and transmitted to the pinion; fortunately, it must be able to withstand - times that amount of transmission torque, and a module may be used to increase the strength of the teeth. If it is thicker, the rack stroke per pinion/rotation will be correspondingly larger, which will result in a smaller gear ratio as described above, so this method cannot be expected to be sufficiently effective. In order to increase the strength of tooth 3- without increasing the tooth module, there is a method of increasing the meshing tooth width of the binion and rack teeth, or increasing the meshing pressure angle, but the former method involves increasing the diameter of the rack shaft. In the latter case, it is necessary to increase the length of the binion and increase the size of the equipment, or the latter increases the component of the reaction force of meshing in the direction of moving the binion and rack shaft apart, increasing the sliding resistance of the rack shaft. Both of these are disadvantageous in the case of a rack and pinion type steering device.

The present invention was made in view of these points, and provides a rack and pinion type steering device that can reduce the size of the binion and rack tooth modules without reducing the transmissible torque, and can obtain a large gear ratio. This purpose is to mesh and engage a rack tooth of a rack shaft forming a part of a steering link with a pinion which is rotatably operated by the rotation of a /% steering link, and a rack shaft which is rotated by the rotation of the pinion. In a rack and pinion type steering device that reciprocates and deflects wheels,
This is achieved by a rack and pinion type steering device characterized by providing a plurality of pinions, each of which meshes with the rack teeth of the rack shaft and is driven to rotate simultaneously by rotation of the handle shaft. Since these multiple binions share and transmit the torque transmitted by the rotation of the handle shaft, the strength required for each tooth is lower, making it possible to reduce the tooth module accordingly, and thus It is possible to increase the gear ratio by reducing the rank stroke for the same amount of rotation. By providing, for example, one of the binions, the strength required for each binion and rack tooth is halved compared to conventional products, thereby reducing the tooth module to approximately 7 without reducing the transmissible torque. You can increase the rack stroke to about 4 and double the gear ratio. By increasing the number of binions, it is possible to use even smaller modules and obtain a wider gear ratio.

Next, the present invention will be described in detail based on embodiments shown in the drawings. 1 and 2 show one embodiment of the present invention, and in the drawings (1) is a rack shaft forming a part of a steering link, which deflects the vehicle. In this embodiment, a first pinion wheel (7a) connected to the handle shaft and directly rotationally driven, and a gear (Ila K4'l))
The pinion (a first pinion (, J'l) that is rotationally driven by the rotation of the side 3a) is provided through the pinion k, and each pinion is rotatably supported within the gear housing (2). . The first pinion (3a) meshes with the first rack tooth row CJa) formed on the rack teeth, and the second pinion (31)) meshes with the first rack tooth row CJa) formed on the opposite side of the rack tooth row 1K5a). It meshes with the rack tooth row (5b).

The first pinion (3a) is rotated in the same direction as the handle shaft by the rotation of the handle i'@ as the handle is turned, and the rack shaft (1) is moved in one direction. At the same time, the first pinion (3b) is rotated in the opposite direction to the first pinion (3a), but meshes with the first rank tooth row (5b) formed on the opposite side of the rack shaft (1). Because
The rack shaft (1) is also moved in the same direction. Therefore handle j! &l] The torque transmitted by the rotation of the first pinion (3a), 1! : 1st pinion (,
J'l)) By sharing this transmission torque, the force required on each tooth of the pinion and rack is lowered, and accordingly the tooth module can be made smaller and the rack stroke relative to the rotation angle of the pinion can be made smaller. This shows an example of rack shaft (1)
Same rack tooth row (left c) Vc broom/pinion (3a)
and the first pinion (3b) are in mesh with each other, and each pinion has a tooth pedestal C) (l
I-d), the gear meshing with a gear (6) connected to the handle shaft. 7th pinion (3a
) and the first pinion (3b) are driven to rotate in the same direction, causing the entire rack shaft to move in the same direction. Similar to the above-described embodiment, the module of the pinion and rack teeth can be made smaller by sharing the transmitted torque, and the rack stroke relative to the pinion rotation angle can be made smaller. In the drawings, (7) is a resilient plunger that urges the rack shaft according to the four pinion rules.

As described above, the present invention is provided with a plurality of pinions, each of which meshes with the rack teeth of the rack shaft and is simultaneously driven to rotate by the rotation of the handle shaft. module can be made smaller, the rack stroke per pinion/rotation can be made smaller, and a rack and pinion type steering device with a larger gear ratio can be obtained, making it possible to apply this type of steering device to large vehicles. It has the effect of being able to do things.

[Brief explanation of the drawing]

Figure 1 is a sectional view of one embodiment of the present invention, and Figure 2 is the same as Figure 1.
A sectional view taken along the -π line, and FIG. 3 is a partially omitted sectional view of another embodiment. 8- Explanation of symbols/...Rack N, 2, gear housing 3a, 3b-=pinion a, %, llc,
4d...Gear addition, squirrel, 3c...Rack tooth row

Claims (1)

[Claims] A rack pinion that meshes and engages a pinion that is rotated by the rotation of a nozzle with the rank teeth of a rank shaft that forms part of the steering link, and deflects the wheels by reciprocating the rack shaft by the rotation of the pinion. 1. A rack and pinion type steering device, characterized in that a plurality of pinions are provided, each of which meshes and engages with rank teeth of a rack shaft and is rotationally driven simultaneously by rotation of a nodule shaft.