JPS5822361B2 - Torsion bar type axle device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a torsion bar set axle device used in the drive system of an automobile to transmit the torque of the propulsion shaft to the wheel bub, and particularly relates to a torsion bar set axle device that is used in the drive system of an automobile and transmits the torque of the propulsion shaft to the wheel bub. This relates to an axle device useful for prevention.

Note that the "axle" here refers to the "drive axle."

First, we will provide an overview of the noise generation phenomenon in suspension systems during low-speed acceleration.

Generally, when accelerating in 1st or 2nd gear, the vehicle accelerates smoothly and does not produce any particularly unpleasant noises, but when shifting to 3rd and especially 4th gear, When accelerating at high speeds, it is common for the rear wheel suspension system to produce an unpleasant thumping sound, and this phenomenon is commonly referred to as "low-speed windup."

When looking at this low-speed windup phenomenon from the perspective of vehicle vibration, it is caused by the rear wheel suspension system causing pitching resonance using vibrational fluctuations in engine torque as an excitation force. In order to prevent wind-up noise, (a) countermeasures against vibration sources such as increasing the number of engines equipped (six cylinders), (b) drive systems that increase the inertia of the flyhole and propulsion shaft. (c) Various measures have been tried in the past, such as measures related to the suspension system, such as making the tamper stronger or increasing the weight of the differential, but none of them have been effective in some way. Due to the problems associated with this, sufficient effects cannot be obtained.
In other words, the current state of prevention technology is to find compromises where appropriate.

The technology according to the present invention effectively suppresses windup noise and is related to drive system structural technology, but its technical basis is different from the conventional countermeasures described above. This is a new technology, and the principle behind the idea of the present technology will be explained here.

First, it has already been mentioned that the windup vibration force is the torsional vibration force of the drive system, but this torsional vibration is caused by the moment of inertia (denoted as ■) of the flywheel, propulsion shaft, wheels, etc., and the clutch, etc. Splash constant of rear axle, etc. (assumed to be k)
The vibration system with multiple degrees of freedom based on Considering that what governs the vibration transmission characteristics of the drive system is the primary resonance frequency of the torsional action, the correlation between the torsion characteristics of the drive system and the vibration transmission rate is shown in Figure 1 under the equal constraint. As shown, single 1
It can be explained as an oscillating system of degrees of freedom.

Therefore, in the branch yarn, the equation of motion when the external force is T is: (1) θ+ is θ2T, and its vibration transmissibility can be approximately determined as 2゛1 - r ω.

As can be seen from this equation, what controls the vibration transmissibility is
Only the resonant frequency ωn is required. Therefore, if the primary torsional frequency of the drive system is lowered than that of the conventional system, vibration transmission in the practical vehicle speed range can be achieved as shown by the solid line in the graph in Figure 2. It is understood that the frequency can be significantly reduced, and the frequency can also be reduced by changing the inertia and elastic collapse of the system.

Note that changing the moment of inertia of a drive system not only involves a considerable increase in vehicle weight, but also causes deterioration in the acceleration performance of the vehicle, so it is difficult to say that it is an effective method from a practical point of view.
On the other hand, by changing the elasticity, for example by changing the torsional rigidity of the axle, it is possible to reduce the frequency without any reduction in practicality.

The present invention has been made based on such a technical idea, and the purpose of the present invention is to reduce the load when the average torque load applied to the axle is small, such as when accelerating in 3rd or 4th gear. By providing an axle with reduced torsional rigidity, it is possible to reduce the vibration frequency of the drive system and suppress wind-up noise, and the structure for suppressing that noise is compact, reducing processing costs and weight increases. To provide a torsion bar complete axle device which does not cause any damage.

The present invention will be described below based on an illustrated embodiment.

In the axle device of the embodiment, as shown in FIGS. 3 and 4, an axle 3 is formed by two drive shafts, an inner and outer shaft, that is, an inner shaft 1 and an outer shaft 2. the inner end of
That is, a spline 9 is formed at the right end in the drawing and is connected to the differential, and the wheel hub 4 is integrally formed at the outer end of the spline 9. , retainer inner 6 and retainer outer 7
It is supported on the vehicle body by a bearing 8 which is sandwiched between the bearings 8 and 8.

Next, the outer shaft 2 made of a hollow shaft is fitted onto the inner shaft 1 at its outer end and welded to the inner shaft 1, and an abutment tube 1 is attached to the inner end.
The outer half of 0 is fitted and welded.

Therefore, on the inner circumferential surface of the inner half 10a of the abutting cylinder 10,
A plurality of rows (four rows) of abutment grooves IQb, which are longitudinal grooves, are bored, and in the abutment grooves 10b, a projection is formed on the outer periphery of the engaging portion 11 near the inner end of the inner shaft 1. , the same number of tooth rows 11a are fitted together.

The groove width of the abutment groove IQb is formed to have an appropriate gap with respect to the tooth width of the tooth row 11a, and in a free state where no torque load is applied to the axle 3, each tooth row 11a is , is in contact with the middle portion of the groove width of the matching groove 10b.

Next, the operation of the axle 3 configured as above will be explained.

The torque applied to the axle 3 while the vehicle is running is composed of an average torque and a variation that varies around the average torque, and the windup vibration force is the variation.

However, as shown in Fig. 5, as in the case of 3rd and 4th speeds,
In a region where the average torque is small, the tooth row 11a is in the abutting groove 10.
Since it is floating in the shaft 1, torque transmission is carried only by the shaft 1, that is, it vibrates in a region where the spring constant is small.

Furthermore, in a region where the average torque is large, such as during 1st and 2nd speeds, the torsion of the inner shaft 1 causes the tooth row 11a to abut against the edge of the abutment groove 10b. In this state, the torsional rigidity of the axle 3 increases and sufficient torsional strength is obtained.

In this way, the torsional rigidity of the axle 3 changes in two stages depending on the torque strength at that time, so in 3rd and 4th gears, the vibration transmission rate decreases and the windup phenomenon is effectively suppressed. In addition, in 2nd speed, sufficiently large torque can be transmitted.

In the implementation of the present invention, in the above configuration, the inner and outer shafts 1 and 2 are fixed on the hub 4 side, but the same effect can be achieved by fixing them on the differential side, that is, on the inner end side. In addition, the inner and outer shafts 1.2 may be fixed by spline engagement instead of welding as described above.

Here, the axle 3 of the above-mentioned embodiment was installed in a passenger car equipped with a 4-cylinder engine, and an experiment was carried out to examine the effect of reducing in-vehicle noise and vibration. It was confirmed that a reduction effect was obtained and that the torque fluctuation characteristics were comparable to those of a 6-cylinder engine.

As described above, according to the torsion bar set axle device according to the present invention, the axle is formed of two inner and outer drive shafts, and one of the drive shafts is allowed to play in response to the transmitted torque. Therefore, when the transmission torque is small, 1. The vibration transmission rate of the drive system is reduced, effectively suppressing noise, and when the transmission torque is large, the torsional rigidity is restored to sufficiently withstand the transmission of severe torque, thereby improving the drivability of the vehicle. It has a remarkable effect on improving the
Furthermore, as is clear from the previous embodiment, large torque is transmitted between the tooth rows protruding from the outer circumferential surface of the drive shaft and the engagement grooves provided on the inner circumferential surface of the outer drive shaft. Since this is done using a so-called spline joint type structure that is achieved by fastening, the large torque transmission section can be very compactly packed, which is extremely advantageous in terms of space. In this case, the effect is that the cover can be made smaller.

[Brief explanation of the drawing]

FIG. 1 is an equivalent diagram of the vibration system of the axle device, FIG. 2 is a graph of vibration transmission characteristics in the axle device, and FIG. 3 is a side view of the torsion bar complete axle device showing an embodiment of the present invention. 4 is a sectional view taken along the line ■-■ in FIG. 3, and FIG. 5 is a graph of the axle torsion angle characteristics in the embodiment device. 1.2... Inner shaft and outer shaft as drive shafts, 1at10b
... tooth row and abutment groove as abutment members, 3... axle,
4...wheels...b.

Claims (1)

[Claims] 1 Used in the drive system of an automobile, it is an axle device that transmits the torque of the propulsion shaft to the wheel hub. A fixed or non-rotating connection between one drive shaft,
On the other end side, a tooth row is provided protruding from the outer circumferential surface of the inner drive shaft, and an appropriate amount is provided on the outer inner circumferential surface of the drive shaft in the circumferential direction relative to the tooth row. Furthermore, the inner end of one of the drive shafts is connected to the propulsion shaft side, and the outer end is connected to the wheel. A torsion bar complete axle device characterized by being formed integrally with a torsion bar.